Tohoku ILC Civil Engineering Plan

October 2020

Tohoku ILC Project Development Center

In cooperation withHigh Energy Accelerator Research Organization

Introduction
Since about 2014, research and examinations have been conducted by the relevant organizations aroundthe proposed site for the civil engineering plan of the International Linear Collider (ILC) that is to beconstructed in the Kitakami site in the Tohoku Region. In cooperation with the High Energy Accelerator
Research Organization, the project now contains the full results from the consideration of the Global Design
Effort for the ILC.
It is important for the technical feasibility of a project for an ILC facility to be evaluated technically interms of rock mechanics and rock engineering because the facility requires large underground works.
Accordingly, an ILC civil engineering plan in the Kitakami site in the Tohoku Region (hereafter referredto the “Tohoku ILC Civil Engineering Plan”) was examined for its technical feasibility by the Evaluation
Subcommittee for ILC Civil Engineering Facility in Tohoku, established under the Committee for RockMechanics, the Japan Society of Civil Engineers (a public interest incorporated association), in the 2019fiscal year. This subcommittee then evaluated the project with the comment of “We assessed the technicalfeasibility of the ‘Tohoku ILC Civil Engineering Plan’ as guaranteed, and concluded that the details of the
project are appropriate.”
The Tohoku ILC Project Development Center opens the details of the construction technology of the civilengineering plan to the public and contributes to various scientific and technical examinations of it in many
fields, considering these activities to be both very beneficial and essential for stepping toward therealization of the ILC. The development center has thus reorganized the technical details of the ILC civilengineering plan in the Kitakami site and has decided to introduce them here.
We expect that the ILC civil engineering plan will be widely understood through this document and theconsideration of the technical details of it will be developed by many specialists in various fields.
Atsuto Suzuki,
Director of the Tohoku ILC Project Development Center

Contribution to disclosing the Tohoku ILC Civil Engineering Plan
The Tohoku ILC Civil Engineering Plan has been established by the Tohoku ILC Preparation Office incooperation with the High Energy Accelerator Research Organization (KEK), and has been evaluated for
its technical feasibility in terms of rock mechanics and rock engineering by the Evaluation Subcommittee
for ILC Civil Engineering Facility in Tohoku in the Committee for Rock Mechanics, the Japan Society of
Civil Engineers (a public interest incorporated association). We describe the circumstances of these
activities and the result of the evaluation by the Japan Society of Civil Engineering below.
Committee for Rock Mechanics, the Japan Society of Civil Engineering
Evaluation Subcommittee for ILC Civil Engineering Facility in Tohoku

I.

Circumstances

1. Tohoku ILC Civil Engineering Plan
The ILC project is based on the Technical Design Report (2013), and has been examined for cost reduction
and other purposes in Japan by international cooperative works with researchers in many countries, with
the High Energy Accelerator Research Organization (KEK) as the central figure. The specifications of the
ILC project have been almost established up to now.
On the other hand, the Tohoku ILC Preparation Office has carried out point surveys, concept design, andother activities independently for the achievement of ILC location in the proposed area of the Tohoku
Region, because the ILC project involves large underground work, and must consider some conditions
intrinsic to its planned point, such as topography and geology.
Adding intrinsic conditions regarding the proposed point to internationally-examined specifications, theTohoku ILC Preparation Office and KEK have established the Tohoku ILC Civil Engineering Plan
described here.

2. Evaluation of the civil engineering plan
The feasibility of the civil engineering plan is required to be satisfactorily guaranteed in terms of rockmechanics and rock engineering, because the construction of the ILC facility involves large undergroundwork. Accordingly, the evaluation of this civil engineering plan was entrusted to the Committee for RockMechanics, the Japan Society of Civil Engineering (a public interest incorporated association), which had
also carried out technical examinations for ILC civil engineering plans as a third party in the past.

3. Evaluation Subcommittee for ILC Civil Engineering Facility in Tohoku in the Committee for RockMechanics, the Japan Society of Civil Engineering
3.1 Establishment of the subcommittee and member line-up
The Committee for Rock Mechanics decided to promote evaluation works by establishing the exclusive“Evaluation Subcommittee for ILC Civil Engineering Facility in Tohoku” under the committee. The
subcommittee members were widely selected from members of the Japanese Society for Rock Mechanics(JSRM) with consideration for their special fields; we then decided to carry out work with an “all-Japanese”
organization in the fields of rock mechanics and rock engineering.

The above-mentioned JSRM is the Japanese branch of the International Society for Rock Mechanics andRock Engineering (ISRM), a global academy of rock mechanics and rock engineering, and is an academic
research organization in cooperation with the Science Council of Japan. The JSRM mainly consists of four
academies, which are the Japan Society of Civil Engineering, the Japanese Geotechnical Society, theMining and Material Processing Institute of Japan, and the Japan Society of Materials Science; thus, mostJapanese researchers and engineers involved in rock mechanics and rock engineering belong to the JSRM.
This subcommittee is headed by Chairman Ohnishi, who is an ex-vice president of the ISRM, along withthe chief director (Ito) and two ex-chief directors (Obara and Kyoya) of the JSRM, and other experienced
members as well as an all-Japanese member line-up consisting of those in the JSRM, becoming a reliable
work team both domestically and internationally.
3.2 Subcommittee member list
ChairmanYuzo Ohnishi(Emeritus Professor in Kyoto University)

Chief Secretary

Takashi Kyoya(Department of Civil and Environmental Engineering in the
Graduate School of Engineering, Tohoku University)

Secretary

Tomoyuki Sanuki(Department of Physics in the Graduate School of Science,
Tohoku University)

Nobuhiro Terunuma(High Energy Accelerator Research Organization)

Jun-ichi Kodama(Division of Sustainable Resources Engineering in the Graduate
School of Engineering, Hokkaido University)

Takafumi Seiki(Division of Social Design in the Graduate School of Regional
Development and Creativity, Utsunomiya University)

Masahiko Osada(Programs of Environmental Science and Civil Engineering in
the Graduate School of Science and Engineering, Saitama
University)

Tomochika Tokunaga(Department of Environment Systems in the Graduate School of
Frontier Sciences, the University of Tokyo)

Kiyoshi Kishida(Department of Urban Management in the Graduate School ofEngineering, Kyoto University)

Tomofumi Koyama(Department of Safety Management in the Faculty of Social
Safety Sciences, Kansai University)

Shinichi Akutagawa(Department of Civil Engineering in the Graduate School ofEngineering, Kobe University)

Hideaki Yasuhara(Engineering for Production and Environment in the Graduate
School of Science and Engineering, Ehime University)

Yasuhiro Mitani(Department of Civil and Structural Engineering in the Graduate
School of Engineering, Kyushu University)

Yuzo Obara(Department of Civil and Environmental Engineering in the
Faculty of Engineering, Kumamoto University)

Takatoshi Ito(Chief director of the Japanese Society for Rock Mechanics)

Yoshinobu Nishimoto(Chairman of the Committee for Rock Mechanics)

Satoru Yamashita(International Center for Elementary Particle Physics, theUniversity of Tokyo)

Shinichiro Michizono(High Energy Accelerator Research Organization)

Member3.3 Activities of the subcommittee
Activities:(1) Explanation of the outline of the ILC project and civil engineering plan(2) Explanation of the Tohoku ILC Civil Engineering Plan
(3) Inspection of the proposed site and extraction of points to note
(4) Summarization of evaluations and points to note

Subcommittee meetings and on-site inspection:- 1st meeting (July 30, 2019)- 2nd meeting (August 30, 2019)- 3rd meeting (November 11, 2019)- On-site inspection (November 27, 2019)- 4th meeting (December 19, 2019)- 5th meeting (February 20, 2020)

The End.

Takashi Kyoya,
Chief Secretary of the Evaluation Subcommittee for ILC Civil Engineering Facility in Tohoku
in the Committee for Rock Mechanics, the Japan Society of Civil Engineering

Ⅱ.

Result of the evaluation of the Tohoku ILC Civil Engineering Plan (extracted)1)

The Evaluation Subcommittee for ILC Civil Engineering Facility in Tohoku concluded that the"Tohoku ILC Civil Engineering Plan" is technically feasible and that the contents of the plan areappropriate.

The Evaluation Subcommittee for ILC Civil Engineering Facility in Tohoku investigated a wide range of
topics covering the entire facility planning process as follows: 1) Description of the ILC Plan Summary
and Civil Engineering Plan, 2) Description of Tohoku ILC Civil Engineering Plan, 3) Field survey of thecandidate site and identification of points to be noted, and 4) Summary of evaluation and points to be noted.
The Subcommittee started the evaluation in mid-July 2019 and completed the work in February 2020. The
features of this facility are that the main tunnel, through which the beams run, has a substantial total lengthof 20.5 km accompanied by five access tunnels (width 8 m, height 7.5 m, semicylindrical shape) and that
there is a large cavern (width 25 m, length 108 m ∼ 133 m, height 42 m) to house the detectors. Due to thevarious impacts arising from the large size of the facility and its underground location, it was necessary totake into account a wide range of perspectives such as rock engineering, geotechnical engineering, andhydrogeology, and to draw on the Japanese civil engineering technologies used in the past to constructtunnels and underground caverns as ordinary facilities, in order to assess the adequacy of the contents ofthe civil engineering plan.
Since the underground facilities will be constructed in underground rock with complex geologicalconditions, the following issues were discussed in this study: investigation of the unique characteristics ofthe proposed construction site; determination of the properties of the ground, rock, and water by surface
and underground exploration; confirmation of the mechanical stability of the underground facilities for theconstruction safety; checking the impact of the design on the safe and rapid constructability of the facilities;
and planning with consideration of economic efficiency.
The Subcommittee, consisting of leading experts in the relevant fields, conducted a careful and thoroughevaluation based on the various exchanges of opinions and concluded that the “Tohoku ILC Civil
Engineering Plan” is technically feasible from an expert’s point of view and that the contents of the plan
are appropriate.

February 20, 2020

Japan Society of Civil Engineers, Committee on Rock Mechanics
Evaluation Subcommittee for ILC Civil Engineering Facility in Tohoku
Chair Yuzo Ohnishi

1）

The result of the evaluation can be viewed on the website of the Evaluation Subcommittee for ILC Civil Engineering Facility in Tohoku in theCommittee for Rock Mechanics, the Japan Society of Civil Engineering (http://www.rock-jsce.org/index.php?ILC_subcommittee_2th).

Table of Contentsix

Table of Contents

PART IINTERNATIONAL LINEAR COLLIDER (ILC)

1 Outline of the ILC Facility

13

1.1 The ILC accelerator ............................................................................................... 3
1.2 ILC underground facility ....................................................................................... 4
2 Design Requirements

5

2.1 Access tunnels and access halls ............................................................................. 5
2.2 Accelerator tunnel .................................................................................................. 8
2.2.1 Damping ring tunnel ...................................................................................... 8
2.2.2 Main linear accelerator tunnel ..................................................................... 10
2.2.3 BDS tunnels ................................................................................................. 12
2.3 Detector hall and peripheral tunnels .................................................................... 14
PART II KITAKAMI SITE

17

3 Topography and Geology

19

3.1 Outline of topography .......................................................................................... 19
3.2 Outline of the geology ......................................................................................... 20
4 Geological Surveys

23

4.1 Description of geological surveys ....................................................................... 23
4.2 Outline of the results of the geological surveys .................................................. 25
PART III TOHOKU ILC CIVIL ENGINEERING PLAN

33

– Tohoku ILC Civil Engineering Plan –xTable of Contents

5 Circumstances and Conditions for Settling the Project35

6 Facility Location

37

6.1 Location plan ....................................................................................................... 37
6.1.1 Concepts of the location plan ....................................................................... 37
6.1.2 ILC facility location plan ............................................................................. 38
7 Access Tunnels and Access Hall41

7.1 Design specifications ........................................................................................... 41
7.1.1 Selection of the positions of pitheads .......................................................... 41
7.1.2 Rock mass classes ........................................................................................ 42
7.1.3 Dimensions and structures of the access tunnels and access halls............... 42
7.2 Construction plan ................................................................................................. 54
7.2.1 Outline of the plan ....................................................................................... 54
7.2.2 Preparation of pithead yards ........................................................................ 54
7.2.3 Excavation method....................................................................................... 54
7.2.4 Temporary facility plan................................................................................ 55
7.2.5 Process plan ................................................................................................. 55
8 Accelerator Tunnel

57

8.1 Design specifications ........................................................................................... 57
8.1.1 Rock mass classes ........................................................................................ 57
8.1.2 Dimensions and structures of the accelerator tunnel ................................... 57
8.2 Construction plan ................................................................................................. 64
8.2.1 Outline of the plan ....................................................................................... 64– Tohoku ILC Civil Engineering Plan –Table of Contents

xi

8.2.2 Outline of the construction process plan ...................................................... 64
9 Detector Hall and Peripheral Tunnels

67

9.1 Design specifications ........................................................................................... 67
9.1.1 Rock mass classes ........................................................................................ 67
9.1.2 Dimensions and structures of the detector hall and peripheral tunnels ....... 67
9.1.3 Design of support ......................................................................................... 69
9.2 Construction plan ................................................................................................. 76
9.2.1 Outline of the construction........................................................................... 76
9.2.2 Outline of the construction process plan ...................................................... 76
10 Drainage Facilities

79

10.1 Requirements of the ILC accelerator for drainage facilities .............................. 79
10.1.1 Accelerator tunnel ...................................................................................... 79
10.1.2 Drainage tunnel .......................................................................................... 79
10.1.3 Drainage system ......................................................................................... 79
10.2 Design specifications ......................................................................................... 80
10.2.1 Condition of constant groundwater inflow rate ......................................... 80
10.2.2 Sectional drainage method in the accelerator tunnel ................................. 80
10.2.3 Dimensions and structures of the drainage tunnel ..................................... 81
10.3 Construction plan ............................................................................................... 89
10.3.1 Outline of the construction......................................................................... 89
10.3.2 Outline of the construction process plan .................................................... 89
11 Outline of the Construction Plan

91

– Tohoku ILC Civil Engineering Plan –xii

Table of Contents

12 Approximate Construction Costs

93

13 Challenges for the Future

95

PART IV APPENDIX99

A Other Facility Location Plans

101

B

103

Present Examination of the Main Beam Dump Cavern (for Reference)

C Examination Drawings (for Reference)– Tohoku ILC Civil Engineering Plan –

107

1

Part I

International Linear Collider (ILC)
Part I International Linear Collider (ILC)– Tohoku ILC Civil Engineering Plan –31 Outline of the ILC Facility

1.1 The ILC accelerator
The configuration of the ILC (International Linear Collider) accelerator is shown in Figure 1.1[1, 2]. First,
an electron source (gun) and a positron source located near the center of ILC generate a large number ofelectrons and positrons for use in the research of elementary particles. Several tens of billions of electronsand positrons form bunches and are injected into the damping rings. The bunch becomes a high-quality
beam while it is circulating in the damping ring. The electron and positron beams from the damping rings
are transported to the ends of the MLs (Main Linear Accelerators; Main Linacs) through the RTMLs (Rings
To Main Linacs), and immediately accelerated by the MLs and transported to the collision point by the
BDS (Beam Delivery System) which finally focus a bunch to an ultrasmall size of several nanometers fore+ e- collision. Elementary particle reactions that happen during the collision are completely recorded by
the detectors installed around the collision point; then, the study of elementary particle physics is carriedout. After passing through the collision point, electron and positron beams are sent to the beam dumps
where they are absorbed.
A linear collider such as the ILC can be extended to perform experiments at further higher energies. Thisis a unique feature of a linear collider because a circular collider cannot change the circumference. The
present ILC project is optimized for the research of the “Higgs boson” which is the most important andurgent research topic at present, with an energy of 250 GeV and a length of 20.5 km. The design allows forextension and upgrade in case the importance of high energy experiments is confirmed by the progress of
ILC research.

Figure 1.1. Configuration of the ILC accelerator.

– Tohoku ILC Civil Engineering Plan –41

Outline of the ILC Facility

1.2 ILC underground facility
Figure 1.2 shows an overview of the underground facility necessary for installing the ILC accelerator.
To install the ML and BDS equipment, the underground tunnels of the electron side and positron side areplaced opposite each other. These tunnels are angled at 14 mrad in the horizontal plane to prevent beams
from entering their opposing accelerator after passing through the collision point. Looped tunnels are
required at both ends of ILC to accommodate the turnaround. In the central region, a tunnel with a racetrack shape for damping rings and a detector hall for two detectors will be constructed.
Five access tunnels are used (one in the center and two each on the electron and positron sides) to connect
the underground tunnel to the surface. The location of access tunnels to the underground tunnels isdetermined by the design of the accelerator. The detector hall will be connected to the surface by two shafts.
The length of the electron side is 10.9 km and that of the positron side is 9.6 km; accordingly, the overall
length is 20.5 km. Since the electron side contains an accelerator system for the positron generation, the lengthof it is longer than that of the positron side.

Figure 1.2. Configuration of the ILC underground facility.

– Tohoku ILC Civil Engineering Plan –52 Design Requirements
2.1 Access tunnels and access halls
The surface facility and underground accelerator tunnel are connected by an Access Tunnel (AT), which isan inclined tunnel for entry. There are two access tunnels connected to the electron side (AT-8, AT-10),
two to the positron side (AT+8 and AT+10), and one to the damping ring and detector hall (AT-DR/DH)2).
At the connection between the access tunnel and the accelerator tunnel, an Access Halls (AH) will be
constructed to install the various kinds of equipment necessary for ILC operation (see Figure 2.1).

Figure 2.1. Access tunnels.

The access tunnels are used for carrying in large devices such as cold boxes and laying various kinds ofcables, pipes, and ducts necessary for ILC operation (see Figure 2.2). In consideration of these uses, thecross section of an access tunnel is determined to be a semicylindrical (horseshoe) shape with a width of 8m and a height of 7.5 m. The maximum slope of the access tunnel is 10% (9% on average) in accordancewith the maximum longitudinal slope of 12% (a special value for the Types 1, 2, and 3 regular roads) statedin the Road Structure Ordinance.
The pithead of the access tunnel is located at the Access Stations (AS) which requires yards with an areaof 18,200 m2 for installing various kinds of equipment such as electrical and mechanical facilities. These
AS yards are also used as temporary yards during construction.
The access hall consists of four domes (called an M dome, E dome, He dome, and S dome respectively)that contain the machinery, electric power equipment, plant for liquid helium, and various service
equipment (see Figures 2.3 and 2.4).
The distance between each access halls and the collision point is determined by the design of the ILC
accelerator.

2

The numbers (-8, -10, +8, and +10) added to the access tunnels are based on the “Technical Design Report [1].”– Tohoku ILC Civil Engineering Plan –62

Design Requirements

Carriageway

Figure 2.2. A plan of piping and cabling in the access tunnel(under consideration).

Access Station

Access Tunnel

Access Hall

(M Dome)(E Dome)(He Dome)(S Dome)Main Linear Accelerator Tunnel

Figure 2.3. An illustration of a connection from an access station to a main linear accelerator tunnel.

– Tohoku ILC Civil Engineering Plan –2.1 Access tunnels and access halls

7

Figure 2.4. An illustration of the access hall.

– Tohoku ILC Civil Engineering Plan –82

Design Requirements

2.2 Accelerator tunnel
The accelerator tunnel consists of the damping ring tunnel, main linear accelerator tunnels, BDS tunnels,
and other tunnels connecting them.

2.2.1 Damping ring tunnel
A tunnel containing damping rings is placed in the central region and has a race-track shape combining
straight and curved sections (see Figure 2.5). The circumference of this tunnel is 3.2 km.

Figure 2.5. Damping ring tunnel.

In the damping ring tunnel, an electron damping ring and a positron damping ring are installed in two layers(see Figure 2.6). The inner space should be large enough to install the third ring for positron to cure thepositron beam performance in future upgrade.
The curved sections of the damping ring tunnel contain longer bending magnets that require an inner spacewith a width of 5.5 m and a height of 4.7 m or more. On the other hand, the straight sections containsuperconducting acceleration modules (cryomodules) and high-frequency generators, which require alarger inner space with a width of 11 m and a height of 5.5 m or more, and a concrete shield wall will be
installed between them.

– Tohoku ILC Civil Engineering Plan –2.2 Accelerator tunnel

9

Figure 2.6. An illustration of the inside of a curved section of the damping ring tunnel.

– Tohoku ILC Civil Engineering Plan –102

Design Requirements

2.2.2 Main linear accelerator tunnel
The main linear accelerator, which accelerates electron and positron beams to the required energy, will be
installed in opposing straight tunnels (see Figure 2.7). In the current plan, which aims for 250 GeV collisionenergy, the lengths of the main linear accelerator tunnels are 7.4 km for the electron side and 7.2 km forthe positron side.

Figure 2.7. Main linear accelerator tunnels.

The main linear accelerator tunnels contain superconductive high-frequency accelerator modules(cryomodules) and high-frequency generators. The yellow cylindrical objects in Figure 2.8 are
cryomodules. Concrete shield walls with a thickness of 1.5 m will be installed in the center of the tunnel
for separating cryomodules and high-frequency generators. In addition to that, power lines, cooling water
piping, and others necessary for the operation of high-frequency generators are installed. A large space also
needs to be ensured for the installation and exchange of cryomodules and other devices. Based on the above
conditions, the inner space of the main linear accelerator tunnel is determined to be a semicylindrical(horseshoe) shape with a width of 9.5 m and a height of 5.5 m.
In the turnaround section, bending magnets are installed to bend the beam path. A semicylindrical(horseshoe) shape tunnel with a width of 4.5 m and a height of 4.0 m is planned because a concrete shieldwall is not necessary.
In addition, the main linear accelerator tunnel should be parallel to the geoid plane because a liquid helium
is used in the cryomodules.

– Tohoku ILC Civil Engineering Plan –2.2 Accelerator tunnel

11

Cryomodules

Cryomodules

Figure 2.8. An illustration of the inside of a main linear accelerator tunnel (shield walls are not shown).

– Tohoku ILC Civil Engineering Plan –122

Design Requirements

2.2.3 BDS tunnels
The Beam Delivery System (BDS) transports the electron and positron beams accelerated by the main
linear accelerator to the collision point. The BDS section has two parallel tunnels3): one is a beam tunnel
that contains a group of magnets forming a BDS beamline, and the other is a service tunnel that contains
power supplies and other equipment necessary for the beamline. The lengths of the BDS tunnel is 3.5 km
for the electron side and 2.4 km for the positron side (see Figure 2.9).

Figure 2.9. BDS tunnels.

The BDS beamline mainly consists of electromagnets. Figure 2.10 shows the ATF2 beamline constructed
at KEK to demonstrate the BDS technology for ILC. The design of the BDS beamline for ILC is an originof the ATF2 beamline though the sizes of them are different by beam energies. In addition, the BDS tunnel
contains the electron/positron source as well as a BDS beamline. Since a cross section is required to belarge due to inconstant distance between these beam lines, a semicylindrical (horseshoe) shape with a widthof 8.0 m and a height of 5.0 m is planned. A cross section of the service tunnel is planned to be asemicylindrical (horseshoe) shape with a width of 4.5 m and a height of 4.0 m, which is large enough tocontain power supply devices for electromagnets4).
To make small electron and positron beams which collide with sufficiently high repetition rate, it isimportant for a beam path not to be bent in a vertical direction (to make a beam path straight) in a BDS
beamline. Thus, the BDS tunnels are constructed in laser straight unlike the main linear accelerator tunnels
which constructed parallel to the geoid plane (see Figure 2.11).

3

These tunnels are integrated into one tunnel in the present design from the result of examinations by the Global Design Effort
for the ILC.
4 A cross section of the integrated tunnel is a semicylindrical (horseshoe) shape with a width of 11 m and a height of 5.5 m.

– Tohoku ILC Civil Engineering Plan –2.2 Accelerator tunnel

13

Figure 2.10. ATF2 beamline to demonstrate the BDS technology.

Laser Straight
Collision
Point

Figure 2.11. Relative position of the ILC accelerator to the geoid plane.

– Tohoku ILC Civil Engineering Plan –142

Design Requirements

2.3 Detector hall and peripheral tunnels
A hall containing detectors is constructed at the point where the electron and positron beams collide. In thisdetector hall, two detectors will be installed on each movable base which brings the detector to the collision
point alternately. Various kinds of machinery such as an air conditioner are also installed in the hall.

Figure 2.12. Detector hall.

The inner space necessary for detectors is determined to have a width of 25 m, a length of 108 m, and aheight of 42 m. In addition to that, the space is planned to be extended by 25 m to contain machinery andother devices, and resulted an underground cavern with a length of 133 m.
The underground detector hall and surface will be connected two shafts, a shaft 18 m in diameter used forcarrying the units of detectors, a shaft 10 m in diameter laying power lines and various kinds of pipes, andan access tunnel (see Figures 2.13 and 2.14). Peripheral tunnels of detector hall have sections with widthsof 8 m and 4 m according to applications.

Damping Ring
Connection Tunnel

Access Tunnel

Linear Section of the Damping
Ring Tunnel

RTML Transport
Route

Shaft

Bypass Tunnel

BDS Tunnel (Positrons)

RTML Transport
Route
Bypass Tunnel

BDS Tunnel (Electrons)
Shaft

Figure 2.13. Plan view of the periphery of the detector hall.

– Tohoku ILC Civil Engineering Plan –2.3 Detector hall and peripheral tunnels

15

Figure 2.14. An illustration of the detector hall and peripheral tunnels.

– Tohoku ILC Civil Engineering Plan –17Part II

Kitakami Site
Part II Kitakami Site

– Tohoku ILC Civil Engineering Plan –19

3 Topography and Geology

3.1 Outline of topography
The Kitakami Mountains are a non-volcanic mountain region that extends 250 km north to south and 80
km east to west. Having ridges of constant height, the mountains are considered to be an uplifted peneplain
with topographical features showing highland-like topography with gentle rises and falls. Though theNortheastern Japan Arc has some developed structural basins, the Kitakami Mountains do not seem to havethem. In addition, the mountains do not have large rivers, and valleys along the rivers in the mountains are
generally wide and gentle.
The planned area for the ILC is in the southern part of the Kitakami Mountains. Figure 3.1 (left) shows a
topographic map of the Kitakami site [3]. Some topographical features of the site include belt-shaped
topography extending from the Hitokabe region along the Toriumi River and drop-shaped topography
extending from the Okita region to Fujisawa-cho. These types of topography correspond to distribution
areas of granites belonging to the Hitokabe and Senmaya plutonic rock bodies, and form a characteristic
topography that borders a granite rock body that is weathered easily due to hard hornfels formed aroundthe granite rock body by contact metamorphism during intrusion. On the western side of the planned area
for the ILC is the Kitakami River, on the west edge of the Kitakami Mountains, flowing down from northto south. Since many rivers in the planned area are tributaries of the Kitakami River, most of them flow
down in a meandering way from east to west. These rivers mainly include, from the north, the Hitokabe
River, Ide River, Satetsu River, and Senmaya River; on the other hand, the Kamiyama River and Tsuya
River near the southern end run to the SSE and flow into the Pacific Ocean. Many mountains with analtitude of 700 to 900 m are formed along the planned area for the ILC. With an altitude of 782 m, Mt.
Abara is the highest mountain among those formed by granite. Since other mountains seem to have a heightof 400 to 500 m, they have a gentle highland-like topography as a whole. Around the circumference of the
granite is a distribution of Mesozoic/Paleozoic strata affected by thermal metamorphism and many
mountains with an altitude of 700 to 800 m. These mountains mainly include, from the north, Mt. Tenguiwa(an altitude of 775 m), Mt. Hourai (788 m), and Mt. Tokusenjou (712 m); in addition, Mt. Murone (895 m)
is the highest mountain in the vicinity and is formed by the intrusion of dike swarms into Paleozoic strata
and the Orikabe plutonic complex.

– Tohoku ILC Civil Engineering Plan –20

3

Topography and Geology

Hitokabe Granite
Rock Body

Mt. Abara

Mt. Tenguiwa

Mt. Hourai

Mt. Hayama,

Mt. Murone

Senmaya Granite
Rock Body

Altitude

Orikabe Granite
Rock Body
Mt. Tokusenjou

10 km

Figure 3.1. A topographic map (left) and a geologic map (right) of the Kitakami site.

3.2 Outline of the geology
The Kitakami Mountains are mainly formed by Paleozoic/Mesozoic sedimentary rocks and Cretaceous
granite intruding into them. The mountains are geologically separated into the Northern and Southern
Kitakami Mountains by a northwest-southeast border, the Hayachine Tectonic Belt extending from
Morioka to Kamaishi. The planned area for the ILC is included in the Southern Kitakami Mountains. The
distribution of geology in the Northern Kitakami Mountains is separated into the west Kuzumaki-Kamaishi
and east Akka-Tanohata belts; while both belts mainly consist of Mesozoic/Paleozoic strata including
allochthons such as cherts, the distribution of geology in the Southern Kitakami Mountains consists ofneritic sedimentary rocks with pre-Silurian as a basement rock. In addition, many plutonic rock bodies
mainly formed by granite intrude into these types of geology.
Figure 3.1 (right) shows a geologic map of the Kitakami site [4]. Extending up to 50 km, the ILC is planned
to penetrate the Hitokabe plutonic rock body, Senmaya plutonic rock body, and Orikabe plutonic complex
which extend into the southwest part of the Southern Kitakami Mountains, and to reach the Mesozoic
Triassic Inai Group in an area south of the site. North of the site, older exposed geology surrounding granite
can be found, and the vicinity of Miyamori and Motai has basic rocks and metamorphic rocks of the preSilurian period, which is a base rock of these regions. On the other hand, on their southern side is
Carboniferous rock contacting the Hitokabe and Senmaya plutonic rock bodies. In addition, the Permianrock is distributed around the Carboniferous rock, Hitokabe plutonic rock body, and Orikabe plutonic
complex while Triasic rocks such as the Inai Group are distributed to the south of it. The Carboniferous
and Permian rock formations consist of lutite and sandstone inserted into limestone while the Triasic– Tohoku ILC Civil Engineering Plan –3.2 Outline of the geology

21

consists of mudstone, sandstone, and alternating strata. The Southern Kitakami Mountains have a fault
structure extending from the Hizume region to the Kesennuma region in the NNW-SSE direction; thisstructure is called the Hizume-Kesennuma Fault. Fold structures in the same direction are widely developedin the Southern Kitakami Mountains, and were supposed to be formed by the Oshima Orogenic Movement
activated mainly in the Cretaceous period. The Oshima Orogenic Movement is considered as a series ofthe following movements: the addition of the allochthonous strata of the Northern Kitakami Mountains
occurred during the time from the middle Jurassic to the early Cretaceous periods due to compression in
the east-west direction; and then, fold structures and faults in the same direction were formed due tovolcanic activity and the intrusion of plutonic rocks. Alluvia and terrace deposits are distributed as younger
sediments in valleys along rivers in the site; in addition to that, the unconformity of the Pliocene covers apart of the western Senmaya granite rock body.

– Tohoku ILC Civil Engineering Plan –23

4 Geological Surveys5

4.1 Description of geological surveys
The geological surveys were conducted almost along a straight line through the Hitokabe granite rock body,
Senmaya granite rock body, and Orikabe granite rock body. Table 4.1 outlines the geological surveys
conducted until now. In addition, Figure 4.1 shows the main survey points along with outlines of theirresults. As of the 2017 fiscal year, we have carried out seismic exploration with an overall length of 30 km,
electromagnetic/electric prospecting with an overall length of 13 km, and boring surveys in six places(seven cores).
Table 4.1. Outline of the geological surveys
Fiscal year

Main survey item

Description of the survey

2009

Ground surface/geology
investigation
Seismic exploration
Radiation survey
Ground surface/geology
investigation
Seismic exploration
Electromagnetic
prospecting
Boring survey
Ground surface/geology
investigation
Airborne laser survey

Investigation of the contact point (“narrow point”) of
the Hitokabe and Senmaya granite rock bodies

2010

2011
2012

2015

2016
2017

Ordered
by
Iwate
Pref.

Investigation of the properties and conditions of the Hitokabe
and Senmaya granite rock bodies
Investigation of the cross points of rivers

TohokuUniv.

Investigation of overviews of Mt. Hayama and the Inai Group

TohokuUniv.
TohokuUniv.
TohokuUniv.

Creation of topographical maps (with a contour of 1m/5m)from the DEM (with a grid of 1m)
Ground surface/geology Investigation of the properties and conditions of geology
investigation
around the proposed collision point Investigation of geologic
Seismic exploration
boundaries
Electromagnetic
Reading of topography
prospecting(Inclined shafts are assumed for accessing the detector hall.)Boring survey
Ground surface/geology Investigation of lineaments and active faults
investigation
Ground surface/geology Investigation of the properties and conditions of geology
investigation
around the proposed collision point
Seismic exploration(Shafts are assumed for accessing the detector hall.)
Electromagnetic
prospecting
Boring survey
Seismic exploration
Investigation of the properties and conditions of the northernslope of Mt. Abara
Seismic exploration
Whole line of 30 km

Iwate
Pref.
TohokuUniv.

TohokuUniv.
TohokuUniv.

5

The outline of the geological surveys conducted up to the 2017 fiscal year is described in material (Material 1-3 for the 6th
Subcommittee Meeting for Technical Examinations held on October 2, 2018) reported to the “Committee of Examinations for the
Reworked Plan of the ILC Project, the Science Council of Japan” (http://www.scj.go.jp/ja/member/iinkai/ILC/ILC24.html). In
this document, the details of the civil engineering plan are simply summarized.

– Tohoku ILC Civil Engineering Plan –24– Tohoku ILC Civil Engineering Plan –Boring Points
Measurement Line of the
Seismic Exploration
Hitokabe Granite Rock Body

Orikabe Granite
Rock Body

Senmaya Granite Rock Body

Cross section of the electromagnetic (electric)
prospecting

H22 and H23 (Hitokabe/Senmaya Boundary)
H22 (Electric Prospecting) (Higashiushiishi)

800

104

H24 (Mt. Hayama)
H22 (Electric Prospecting) (Satetsu Riv.)

600

103

400

102
H27 (Kawamata through Toriumi to Okita)

200

Cross section of the seismic exploration
800

H22(Higashiushiishi) H24(Okita River)

H24
H24 (Hitokabe),(Hitokabe),

600

H24
(Senmaya/Orikabe
Boundary)

H24(Mt. Hayama)
Satetus
Riv

Ide River

Sokei
Riv

Senmaya
Riv

4.3

3.0

Senmaya
Riv

400

Cross section of the geology

H28 (North of Mt. Abara)

H29 (Mt. Abara to Toriumi)

Mt. Abara

800
600

Intrusion Limit

Senmaya Plutonic
Rock Body

Hitokabe Plutonic
Rock Body

Fault

Orikabe Plutonic
Complex

Hydrothermal Alteration
Mt.
Tokusenjou

Mesozoic
Stratum

YahazuRiv

Weathering Limit (higher rank: classes D to CL, lower rank: classes
CM to B)Ide River

Okita Riv

400

0

0.3
(km/s)

H29 (Ohara to Sokei)

H27 (Tokorogami to H27 (Hosoda to Okita)
Kawamata)

Satetus
Riv

Sokei Riv

SenmayaRiv

SenmayaRiv

Porphyrite

10

20

30

40

50 km

4
Geological Surveys

Figure 4.1. Outline of the results of the geological surveys.

4.2 Outline of the results of the geological surveys

25

4.2 Outline of the results of the geological surveys
Electromagnetic (electric) prospecting
The result of the electromagnetic (electric) prospecting in Figure 4.1 shows that electric resistivities for a
depth of 100 m or more were generally as high as 104 Ω·m or more while some of them were 102 to 103Ω·m locally. Though places with low electric resistivities are suspected to have fissures containing water,rock mass having a few fissures can be expected to extend in the almost whole area.

Seismic exploration

Elastic Wave
Speed (km/s)

Altitude (m)The result of the seismic exploration in Figure 4.1 shows that the elastic wave speeds (P wave speeds) were
4 to 5 km/s, which is very high, at points other than near the ground surface. As described in Chapter 6, theTohoku ILC Civil Engineering Plan has determined the planned altitude of the ILC tunnel to be 110 m.
Figure 4.2 shows elastic wave speeds at altitudes of 100 m and 120 m. The speeds were generally 5 km/s
or more near the planned altitude of the ILC tunnel. Though the accuracy of seismic exploration may beproblematic near a distance of 5 km due to a large overburden, elastic wave speeds can also be expected tobe 5 km or more near an altitude of 110 m because the speeds were over 4 km/s even near the groundsurface. On the other hand, the elastic wave speeds on the cross points of rivers with a small overburden
were approximately 4 km/s or lower. The cross points of Okita River and Satetsu River had speeds of 3
km/s and 2 km/s, respectively.

Ide Riv.

Okita Riv.

Satetsu Riv.

Sokei Riv. Senmaya Riv.

Distance (km)Figure 4.2. Elastic wave speeds (P wave speeds).

– Tohoku ILC Civil Engineering Plan –26

4

Geological Surveys

Boring surveys
In a boring survey, we obtained the overall length of a core and conducted various kinds of well logging
using a borehole.
Figure 4.3 shows pictures and the RQD values of the cores near an altitude of 110 m that is planned for theaccelerator tunnel. Granite rocks are shown to be widely distributed at the tunnel altitude regardless of thealtitude of the ground surface. In addition, since the RQD values are generally 80% or more for the borings
other than the H24-2 and H22-1’ borings, rock mass with a few fissures are supposed to be distributed.
The H24-2 and H22-1/-1’ borings were performed in the riverbanks of Hitokabe River and Satetsu River
with the aim of investigating the properties and conditions of surface soil and the weathering conditions of
granites in zones with thin overburden. The cores obtained in these two borings were disintegrated into
granite sand by finger pressure. The place where the H22-1’ boring had been conducted was assessed as alow specific resistance zone by electric prospecting. On the other hand, the H22-1 boring conducted at aplace about 100 m away from the H22-1’ boring resulted in very good quality granite. Thus, the cross zonesof the rivers are supposed to have some places locally affected by strong weathering or hydrothermal
alteration.

Borehole camera
We observed the inner walls of the boreholes with a borehole camera.
The borehole camera observation allowed us to read various fissures mainly consisting of joints. Figure 4.4
shows the frequency distribution of fissures that we observed. The Senmaya granite rock body was shownto have many fissures with a low angle inclination close to the horizontal. The Hitokabe granite rock bodywas shown to have many fissures inclined in the ENE-WSW strike direction to the south. Figure 4.4 also
shows the axial direction of the ILC tunnel and the major axis of the detector hall in the facility location
plan described in Chapter 6.

Measurement of initial stress
Using a borehole (H24-1) near the top of Mt. Hayama, we measured initial stress of the ground by ahydraulic fracturing method. Table 4.2 and Figure 4.5 show the result of the measurement.
Since the initial stress obtained by the measurement is the same as those measured in Japan, the site issupposed to have non-special initial stress state.

– Tohoku ILC Civil Engineering Plan –4.2 Outline of the results of the geological surveys

Hitokabe Granite Rock Body

27

Senmaya Granite Rock Body

Orikabe Granite Rock Body

H24-2 (Hitokabe granite rock body, a borehole at analtitude of 146 m)

H22-3 (Hitokabe granite rock body, a borehole at analtitude of 210 m)

H22-2 (Senmaya granite rock body, a borehole at analtitude of 214 m)

H27-1 (Senmaya granite rock body, a borehole at analtitude of 231 m)

H24-1 (Senmaya granite rock body, a borehole at analtitude of 346 m)

H22-1 (Senmaya granite rock body, a borehole at analtitude of 128 m)

RQD (%)

H22-1’ (Senmaya granite rock body, a borehole at analtitude of 130 m)

Altitude (m)Figure 4.3. Pictures and the RQD of the cores near an altitude of 110 m (the numbers added to the core
pictures indicate depths (m)).

– Tohoku ILC Civil Engineering Plan –28

4

Hitokabe Granite Rock Body

Senmaya Granite Rock Body

Geological Surveys

Orikabe Granite Rock Body

H24-2 (Hitokabe granite rock body, a borehole at analtitude of 146 m)

H22-3 (Hitokabe granite rock body, a borehole at analtitude of 210 m)

H22-2 (Senmaya granite rock body, a borehole at analtitude of 214 m)

H27-1 (Senmaya granite rock body, a borehole at analtitude of 231 m)

H24-1 (Senmaya granite rock body, a borehole at analtitude of 346 m)

H22-1 (Senmaya granite rock body, a borehole at analtitude of 128 m)

Figure 4.4. Frequency distributions of fissures observed with a borehole camera. The Schmidt net (equalarea projection) is used on a stereonet to express a pole projection chart of a lower hemisphere. Solid lines
represent the axial direction of the ILC tunnel, and broken lines represent the main axial direction of thedetector hall.

– Tohoku ILC Civil Engineering Plan –4.2 Outline of the results of the geological surveys

Table 4.2.

29

Result of the measurement of initial stress

Depth
(m)

Altitude(m)

Maximum
principal stress
σHmax (MPa)Minimum
principal stress
σHmin (MPa)Verticalstress1σz (MPa)

200.1
210.7
230.0
247.3
261.7
296.5

145.9
135.3
116.0
98.7
84.3
49.5

9.49
9.68
10.72
11.31
9.45
10.59

5.11
6.17
5.75
5.83
5.34
6.10

5.36
5.64
6.16
6.62
7.01
7.94

Maximum
lateral stressratio
σHmax/σz
1.77
1.71
1.74
1.71
1.35
1.33

Direction of
σHmax(degree)N44-86W
N54-77W
N14-39W
N21-35W
N32W
N45W

1 The density of a rock mass is assumed to be 2.73 g/cm3.

Direction of σHmax(degree)

Depth (m)Maximum lateralstress ratio

Depth (m)Depth (m)Initial groundstress(MPa)

Figure 4.5. Result of the measurement of initial stress.

– Tohoku ILC Civil Engineering Plan –30

4Geological Surveys

Laboratory rock specimen tests
We conducted laboratory rock specimen tests for grasping the properties of the granite. For places where
the intrusion of porphyrite was shown, we also conducted tests for porphyrite. Table 4.3 shows the resultsof these tests.
From the measurement, granite rocks at an altitude of 120 m or less were shown to have a uniaxial
compressive strength of 129 MPa or more and a splitting tensile strength of 7 MPa or more. Intruding
porphyrites were also shown to have almost the same uniaxial compressive strength as the granite.
Ultrasonic speeds are consistent with the speeds obtained by the seismic exploration.
Table 4.3. Results of the Laboratory rock specimen tests
Borehole
H24-2
HitokabeH22-3
graniterock body H22-3
H22-3
H22-2
H22-2
H22-2
H24-1
H24-1
SenmayaH24-1
graniteH24-1rock body
H24-1
H24-1
H22-1
H22-1
H22-1

Altitude of asample(m)Type

129.3 – 130.3
95.1 – 95.4
86.0 – 86.3
81.5 – 85.8
129.0 – 129.3
87.7 – 88.0
82.0 – 82.3
145.7 – 146.0
135.2 – 135.5
115.9 – 116.2
98.6 – 98.9
84.1 – 84.4
49.4 – 49.7

GranitePorphyrite
GraniteGranitePorphyrite
GraniteGraniteGraniteGraniteGraniteGraniteGraniteGraniteUniaxial
compressive
strength
(MPa)
141
121
194
166
253
161
129
90
76
153
142
152
158

GraniteGraniteGranite

176
169
176

89.4
87.4
83.3

– 89.7– 88.8– 83.7

splitting tensile
strength(MPa)

VP (m/s)

VS (m/s)

11.70
—
—
—
—
—
—
8.51
8.69
8.74
10.00
7.31
9.28

6,290
5,680
5,670
5,780
5,770
5,430
5,310
6,220
6,230
6,270
6,040
6,100
5,850

3,190
3,400
3,400
3,500
3,350
3,240
3,190
3,170
3,160
3,180
3,140
3,130
3,040

—
—
—

5,240
5,110
4,880

3,720
3,180
2,940

Ultrasonic speed

Fluorescence X-ray analysis
The cores obtained by the boring surveys had some friable and/or discolored regions locally. Since theseregions are suspected to be affected by mineralization/alteration, we obtained samples fromfriable/discolored regions to conduct fluorescence X-ray analysis. Table 4.4 shows the results of theanalysis. These results of the fluorescence X-ray analysis do not show any signs of mineralization or othereffects; thus, the site is supposed to have granite with natural conditions.

– Tohoku ILC Civil Engineering Plan –4.2 Outline of the results of the geological surveys

Table 4.4.
Na2O
MgO
Al2O3
SiO2
P2O5
S
K2O
CaO
TiO2
MnO
Fe2O3
V
Cr
Co
Ni
Cu
Zn
As
Rb
Sr
Y
Zr
Nb
Sn
Sb
Cs
Ba
La
Ce
Pr
Nd
Pb
Th
Cd
U

%
%
%
%
%
%
%
%
%
%
%
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm

31

Results of the fluorescence X-ray analysis

Hitokabe Hitokabe Senmaya Senmaya Senmaya Senmaya Senmaya Senmaya Senmaya Senmaya
3.31
4.13
3.39
3.67
3.79
3.77
1.94
0.67
2.18
3.68
1.73
0.84
2.03
2.15
2.05
2.77
1.53
2.07
1.89
2.56
15.1
17.4
17.5
16.0
16.0
16.1
18.0
20.3
17.0
16.6
68.3
75.2
68.0
70.2
67.3
67.2
67.0
63.9
67.4
67.0
0.138
0.075
0.094
0.151
0.108
0.126
0.091
0.099
0.125
0.102
-0.029-0.026-0.026-0.021-0.024-0.026-0.026-0.022-0.022-0.025
2.65
2.20
1.57
2.21
1.94
1.82
1.12
1.27
1.28
1.43
4.40
4.45
5.49
4.94
4.97
5.52
7.49
7.94
6.49
5.70
0.49
0.22
0.45
0.47
0.46
0.55
0.37
0.38
0.44
0.48
0.08
0.03
0.07
0.08
0.07
0.09
0.09
0.05
0.07
0.09
4.52
2.08
4.28
4.33
4.59
5.25
3.95
3.90
4.70
4.96
78.6
43.8
85.2
84.5
89.2
111
94.3
101
102
103
15.9
9.36
16.3
15.3
16.7
41.9
34.7
42.3
37.9
37.6
11.5
4.60
10.8
11.3
12.4
14.3
9.24
8.96
12.1
13.4
12.7
9.29
14.9
14.0
15.3
21.1
17.6
15.4
18.1
20.3
10.8
9.76
16.8
13.8
15.8
15.9
26.2
56.4
58.8
24.4
61.2
37.0
55.3
59.0
58.1
64.9
48.3
45.7
53.7
61.2
1.51
1.83
3.18
1.87
0.67
0.50
0.93
0.61
0.51
0.97
79.2
59.4
33.5
63.8
52.9
49.4
19.1
21.0
33.3
40.0
276
310
310
348
359
382
163
106
200
380
10.4
3.33
10.6
14.4
12.3
13.9
9.80
10.2
11.4
15.8
102
90.0
101
108
111
107
84.6
93.6
114
133
6.60
4.54
3.93
4.78
4.83
4.75
3.96
4.18
4.75
4.81
1.17
0.68
0.78
0.76
0.42
0.60
0.91
0.78
0.93
0.82
0.49
0.36
0.82
0.60
0.06
0.09
0.50
0.38
0.34
0.11
4.54
2.12
1.71
4.06
2.40
1.85
3.22
2.65
4.36
2.32
361
347
348
406
363
347
329
248
343
299
23.6
12.4
7.61
4.83
10.7
8.80
7.51
43.9
8.87
10.1
37.4
20.8
18.9
13.7
23.1
20.7
17.4
40.8
18.1
24.3
2.09
0.80
0.80
0.80
1.54
1.61
0.97
4.24
1.78
4.28
10.7
5.54
9.07
8.23
10.3
10.7
7.63
17.7
9.03
12.2
14.2
15.2
9.10
11.2
9.52
8.48
9.21
8.95
8.05
8.64
10.8
5.62
3.34
5.00
3.88
2.85
3.28
3.70
2.42
3.22
-0.05
0.14
0.08
-0.10
-0.07
0.10
-0.02
0.14
-0.02
-0.04
3.76
3.68
3.24
4.48
3.52
3.30
1.18
3.23
1.62
3.25

– Tohoku ILC Civil Engineering Plan –32

4

Geological Surveys

Estimation of the constant groundwater inflow rate
We estimated the constant inflow rate of groundwater into the tunnel based on the topography, tunnel route,and specific discharge of base flow (river flowrate during dry periods divided by the catchment area) bymeans of the “GIS-based Tunnel Groundwater Inflow-Rate Prediction System"[7] based on the"Hydrogeological Approach"[5,6] developed by the Railway Technical Research Institute (a public interest
incorporated foundation). Digital Elevation Model (DEM) of the Fundamental Geospatial Data from theGeospatial Information Authority of Japan was used for the topography modeling, and the data from theWater Information System of the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) wasused for the river flow rates of the three river systems (Hitokabe River, Satetsu River, and Senmaya River).
As a result, the average groundwater inflow rate along the entire tunnel route was estimated to be 0.8
m3/min/km.

– Tohoku ILC Civil Engineering Plan –33Part III

Tohoku ILC Civil Engineering Plan
Part III Tohoku ILC Civil Engineering Plan

– Tohoku ILC Civil Engineering Plan –35

5 Circumstances and Conditions for Settling the ProjectIn the Tohoku Region, the proposed place for ILC location, we have considered various details of theconstruction of the ILC in the Kitakami Site on the basis of the Technical Design Report (TDR)[1, 2]
established by the Global Design Effort.
We entrusted investigation work to the Tohoku Branch of the Japanese Geotechnical Society (a public
interest incorporated association) from the 2014 to 2017 fiscal years to examine the details of components
such as the ILC accelerator tunnel, detector hall, access tunnels, and the positions of pitheads. Since the2016 fiscal year, we have been examining them in cooperation with the High Energy Accelerator Research
Organization. In the examination, we investigated the results of geological surveys, ambient environment
conditions, and other situations, and then selected a reasonable location for the underground facility
according to technical and economical evaluation. We also checked the topography of the site and thepositions of structures and selected the positions of the pitheads of the access tunnels through on-site
investigation. In addition, we considered the construction plan and estimated the processes and costs of theconstruction.
The Global Design Effort still updated the design during the examination conducted by the above-mentioned
entrusted Japanese Geotechnical Society. The main updates of the design were changes in the cross sectionof a main linear accelerator tunnel (its width was changed to 11 m, to 9 m, and then to 9.5 m in the 2015
and 2016 fiscal years) and in the length at the start of experiments (it was changed from approximately 30
km to approximately 20 km in the 2016 fiscal year).

Because of the circumstances mentioned above, the Tohoku ILC Civil Engineering Plan described fromthe next chapter is settled under the following conditions.

Construction plan: In accordance with the Civil Engineering Estimation Standards (the 2014 fiscal year
edition) of the Ministry of Land, Infrastructure, Transport, and Tourism.
•

The plan was in accordance with the above standards even for design changes conducted during
the settlement of the plan.
–

–
•
•
•

For changes in the cross section of a main linear accelerator tunnel, widths of 11 m and 9m were examined in accordance with the above standards. For the change in width to 9.5m, the result of the examination for a width of 9 m was converted on the basis of a crosssection for the evaluation of costs and excavation processes (per month); for the evaluationof roadbed processes, it was converted on the basis of the tunnel width.
For the change in length, unnecessary content due to extension/shortening was able to be
excluded.

When a cross section is in a state of unconformity to the above standards due to its large size,
the above standards were applied by setting the cycle time of construction.
The plan was in accordance with the Technical standards for road tunnels of the Japan Road
Association that is equal to the above standards as necessary.
Shafts were in accordance with the Standard Design Specifications Vol. 3 Tunnels of the East,
Central, and West Nippon Expressway Company and the Road Tunnel Technical Standards of
the Japan Road Association.

– Tohoku ILC Civil Engineering Plan –36

5Circumstances and Conditions for Settling the Project

Equipment ownership costs: In accordance with the Table of Construction Equipment Ownership Costs(the 2014 fiscal year edition).
Material unit costs: In accordance with the Construction Material Prices List (August, the 2014 fiscal year)
and the Estimation Data (August, the 2014 fiscal year).

Labor unit cost: In accordance with the Unit Labor Cost for Public Works (the 2014 fiscal year).

– Tohoku ILC Civil Engineering Plan –37

6 Facility Location

6.1 Location plan
6.1.1 Concepts of the location plan
The ILC facility location plan was established according to the following concepts.

Containing the whole of the ILC accelerators in the granite rock bodies
To minimize risks for tunnel excavation crossing geologic boundaries and faults, we aimed to contain the
ILC underground facility in the three granite rock bodies (Hitokabe, Senamaya, and Orikabe granite rockbodies).
If the ILC facility is to be contained in the granite rock bodies, the flexibility of routes is limited because
the accelerator tunnel passes the “narrowed point” of the granite existing in the contact point between the
Hitokabe and Senmaya granite rock bodies. On the other hand, risks for the tunnel excavation are expected
to be minimized because the tunnel can pass the boundary zone of the granite rock bodies along the shortest
route.
Unlike circular accelerators, the ILC has the very important feature of being able to improve its
performance (to reach further higher energy) by extension. Examining the facility location plan, we checkedthat it will be able to extend up to 50 km in the future.

Determining the altitude of the accelerator tunnel to be as high as possible (determining theoverburden of the shallowest point to be about 2D)
A shorter length access tunnel (inclined shaft) connecting the ground surface and underground facility isadvantageous in terms of convenience for usage and construction costs. Thus, we determined the altitudeof the accelerator tunnel to be as high as possible. On the other hand, to guarantee the stability of the tunnel
and avoid the influences of above ground vibration and temperature changes, we decided to ensure
overburden with a thickness of approximately 2D (D is a width of 9.5 m of the accelerator tunnel) for theshallowest point.
The cross point of Satetsu River has the lowest ground surface altitude in this site. The altitude of the ILC
underground facility is to be determined by the riverbed altitude of the cross point of Satetsu River.

– Tohoku ILC Civil Engineering Plan –38

6Facility Location

Considering the present land use conditions
Villages are interspersed along the bank of Satetsu River. For the shallowest point (the cross point of Satetus
River), we decided to locate the ILC underground facility without interfering regions where many houses
gather.

Considering the stability and workability of the detector hall and shafts
To guarantee the stability of the detector hall, we planned to ensure intact rocks with a thickness of 2D (Dis a height of 42 m of the detector hall) as overburden for the hall.

The ILC underground facility location plan was settled according to the above-mentioned concepts. If it isdecided that the accelerator tunnel is to pass the Hitokabe granite rock body that is long in the north-south
direction and the “narrowed point,” its location in the east-west direction and angle of direction are almost
determined. In addition, the altitude of the floor of the tunnel is determined to be 110 m above sea levelaccording to the altitude of the shallowest point (the cross point of Satetsu River).
Assuming that the thickness of a weathered layer is 30 m with reference to the result of the geologicalsurveys, the detector hall should be constructed at a ground surface altitude of approximately 250 m.
The location in the north-south direction of the ILC facility depends on the position of the detector hall.
Under the condition that both ground surface altitude is approximately 250 m and the above-groundfacilities necessary for the operation of the ILC can be constructed, we examined the following two facility
location plans: one is that the detector hall is placed to the south of Okita River, and the other is that thehall is placed to the north of Okita River. The comparison between these two plans shows that the former
has advantages in terms of the construction period and costs of public works, while the latter features ahighly flexible design. From this point forward, we describe the former, the “facility location plan to thesouth of Okita River.” Note that the granite rock bodies can be excavated in any place other than thesouthern end of the accelerator tunnel when the tunnel will be extended to 50 km in the future.

6.1.2 ILC facility location plan
Figures 6.1[3] and 6.2[4] show the ILC facility location plan. As shown in Figures 3.1 and 6.1, thesurrounding area of the ILC facility tends to have a higher altitude on its eastern side than its western side.
Since the lower altitude of a pithead is advantageous in shortening the length of an access tunnel, the accesstunnels are determined to connect to the accelerator tunnel from the western side of the ILC facility. As
shown in Figure 6.2, in addition, the ILC facility is contained in the Hitokabe and Senmaya granite rockbodies.

– Tohoku ILC Civil Engineering Plan –6.1 Location plan

39

Figure 6.1. A plan view of the topography of the ILC facility location plan (blue line: the main
linear accelerator for electrons (a length of 10.9 km), red line: the main linear accelerator for positrons(a length of 9.6 km)).

– Tohoku ILC Civil Engineering Plan –40

6Facility Location

Figure 6.2. A plan view of the geology of the ILC facility location plan (blue line: the main linear
accelerator for electrons (a length of 10.9 km), red line: the main linear accelerator for positrons (alength of 9.6 km)).

– Tohoku ILC Civil Engineering Plan –41

7 Access Tunnels and Access Hall

7.1 Design specifications
7.1.1 Selection of the positions of pitheads
As shown in Figure 2.7, since the distance of the access halls to the collision point is determined by thedesign of the accelerator, the connection points between the accelerator tunnel and access tunnels are
determined according to the position of the collision point. We narrowed the proposed positions of pitheads
under this condition so that the lengths of the access tunnels are as short as possible. In addition, we
conducted an on-site investigation to research the proposed positions and the vicinity, and established thepositions of pitheads more realistically.
The gradient of an access tunnel was determined to be 10% sloping downward for 90% of the overall lengthand horizontal for 10%; thus, an access tunnel was determined to extend from the pithead to the boundaryof an access hall with an average falling gradient of 9%. The floor of an access hall was determined to be
horizontal, and the altitude of the floor was determined to be 110 m which is same as that of the main linear
accelerator tunnels.
Table 7.1 shows a list of the specifications of the access tunnels. A yard area in the table is a site area thatcan be ensured in front of a pithead. The uniform area of 19,000 m2 means that it can ensure an area (18,200m2) necessary for the installation of equipment and other purposes after the completion of the public works.
In addition, two access tunnels connecting to the detector hall (AT-DH) and to the damping rings (AT-DR)
were planned to have the same pithead and pithead yard (AS-DH and AS-DR are same) and diverge
midway.
Table 7.1. List of the specifications of the access tunnels
Entry point(pithead)

Yard area
(m2)

AS−10
AS− 8
AS−DH
AS−DR
AS+ 8
AS+10

19,00019,000Pitheadaltitude
(m)
250
170

19,000170

19,00019,000135
200

Average
gradient
(%)
−9.0
−9.0
−3.1
−9.0
−9.0
−9.0

Length
(m)
1,707
817
747
817
427
1,147

– Tohoku ILC Civil Engineering Plan –42

7

Access Tunnels and Access Hall

7.1.2 Rock mass classes
The access tunnels are to be excavated from the ground surface by passing a weathering zone though a hardrock mass with classes B to CH is assumed for the evaluation of the rock mass at the depth of the main
linear accelerator tunnels. Considering weathering progression near to the overburden of 30 m withreference to the results of the on-site investigation and seismic exploration, support patterns of the accesstunnels were assumed to be as follows according to the depth of overburden. Tunnel support patterns
corresponding to rock mass classes were determined in accordance with the Public Work Estimation
Standards of the Ministry of Land, Infrastructure, Transport, and Tourism.
•

From the “pithead” to the “overburden of 2D (16 m)”: Pattern pithead-DIII•

From the “overburden of 2D (16 m)” to the “overburden of 30 m” (weathering zone): Pattern
DI•

From the “overburden of 30 m” to the “floor altitude same as the main linear accelerator tunnels(110 m)”: Pattern CII•

The “floor altitude same as the main linear accelerator tunnels (110 m)”: Pattern CI

To conduct more detailed design, detailed geological surveys are required for pithead points as necessary.

7.1.3 Dimensions and structures of the access tunnels and access halls
The cross sections of access tunnels and access halls are as follows:1.

Access tunnel: a width of 8.0 m and a height of 7.5 m

2.

Access halls (S dome, E dome, and M dome): a width of 14.0 m and a height of 12.0 m

3.

Access hall (He dome): a width of 20.0 m and a height of 12.0 m

A tunnel with a width of 8.0 m has difficulty in allowing dump trucks, concrete mixing transport trucks,
and crane trucks to change direction. Considering a vehicle can change its direction during construction
and can easily pass after the completion, it was decided to have access tunnels with emergency parking
zones and reversal pits (with a widening of 2 m and a length of 30 m horizontally) placed at intervals of
approximately 300 m.
For the access tunnels connecting the detector hall and damping rings, it was decided to widen the finishedwidth of the cross section of the common section (a length of 537 m) to 10.0 m (same as that of an
emergency parking zone) because large vehicles are congested in the section from the pithead to the fork.
Access tunnels other than the pithead-DIII section were determined to have single shell structures omitting
lining concrete, where shotcrete lining with a thickness of 15 cm was determined, as well as shotcrete forprimary support during excavation.

– Tohoku ILC Civil Engineering Plan –7.1 Design specifications

43

The access halls were determined to have structures with shotcrete lining instead of lining concrete, eventhough they contain devices. Standard cross-sectional views and support patterns of each rock mass classof the access tunnels are shown as follows: Figures 7.1 to 7.4 show those of the standard section; Figures
7.5 to 7.7 show those of a section for emergency parking zones; and Figure 7.8 shows those of a section
for widening. In addition, Figures 7.9 and 7.10 show standard cross-sectional views and support patternsof an He dome and an S/E/M dome of the access halls.
Other outlines of structures are as follows:•

The pithead-DIII section applied an all ground fastening method (AGF method) and wasdetermined to have an invert closing (ring structure) cross section. In addition, lining concrete(with reinforcing iron bars and waterproof sheets) was determined.

•

For waterproof work, the pithead-DIII section was determined to have waterproof sheets, andother sections were determined to have only drainage materials because of single shell structures.

– Tohoku ILC Civil Engineering Plan –44– Tohoku ILC Civil Engineering Plan –Rock Bolts
L = 3.0 m (a yield strength of 117.7 kN or more)

Shotcrete
LiningShotcrete

Floor SlabCentralDrainage
Lining Shotcretet = 100 mm (18 N/mm2)
Shotcretet = 100 mm (18 N/mm2)

Table of unit quantities

Table of specifications

Name
Cross section of excavation(design)
Cross section of excavation(pay line)

Specification

Unit

Quantity

Remarks

An outbreak of 22 cm

m2

64.521 Per 1.0 m

Steel arch support

H-125

units

Shotcrete

ｔ=100

m2

Rock bolt

L = 3.0 m, a yield strengthof 117.7 kN or more

piecesShot lining

ｔ=100

m2

Lining concrete

ｔ=300

m3

- Per 1.0 m

Roadbed concrete

ｔ=400

m3

3.1 Per 1.0 m

Central drainage (drainpipe)

Φ300 (perforated pipe)m10.0 Per 10.0 m

m3

6.956 Per 10.0 m

m3

6.016 Per 10.0 m

Central drainage (excavation)
Central drainage (filter)

ｓ-20- Per 1.5 m
20.555 Per 1.0 m

Steel arch support
Lengthdirection

Lining thickness

Upper half Lower half

1.5

-

Shot
thickness-ShotliningWire net

10-

Arch/sidewall
10

AssistancemethodInvert--Table of the amount of a shot material
Name

13 Per 1.5 m
Shotcrete

Dimension
ｔ＝100

Standard
σ28=18N/mm2

Unit
m2/m

Quantity

Remarks

20.55520.556 Per 1.0 m

Table of the quantity of rock bolt materials
NameDimensionStandard

Unit

Quantity

Remarks

Rock bolt

L=3,000

A yield strength of
117.7 kN or more

pieces13 Mortar adheres to all surfaces

Washer150x150x9ｓｓ400

pieces13

M24

pieces13

Nut-

Figure 7.1. Standard cross-sectional view (left) and support pattern (right) of the standard section of an access tunnel in the CI section.

Access Tunnels and Access Hall59.854 Per 1.0 m

mRock bolt
Circumfere
Lengthntial
direction
3.0
1.5

7

2

7.1 Design specifications

Rock Bolts L = 3.0 m(a yield strength of 176.5 kN or more)

Shotcrete

Steel Support
H-125 (Upper Half)

Lining Shotcrete

Floor SlabCentralDrainage
Lining Shotcretet = 150 mm (18 N/mm2)
Shotcrete

Table of unit quantities

Table of specifications

Name

Specification

Cross section of excavation(design)
Cross section of excavation (payAn outbreak of 20 cm
line)

Unit
m2
m2

Quantity

Remarks

60.900 Per 1.0 m

units

t=100

m2

Rock bolt

L = 3.0 m, a yield strength ofpieces
17.65 kN or more

Shot lining

t=150

m2

Lining concrete

t=300

m3

- Per 1.0 m

Roadbed concrete

t=400

m3

3.1 Per 1.0 m

Φ300 (perforated pipe)

Central drainage (filter)

s-20

Upper
half

1.2

Lining thickness
Shot
thickness

Lower
half

H-125

-

Shot
liningWire net

10-

Arch/sidewall

15

Assistance method

Invert---Table of the amount of a shot material

20.713 Per 1.0 m
13 Per 1.2 m

Steel arch support
Lengthdirection

Name
Shotcrete

DimensionStandard
σ28=18N/mm2

t=100

Unit
m2/m

Quantity

Remarks

20.71420.714 Per 1.0 m

Table of the quantity of rock bolt materials
NameDimensionStandard

Unit

Quantity

Remarksm

10 Per 10.0 m

Rock bolt

L=3,000

A yield strength of
17.65 kN or more

pieces13 Mortar adheres to all surfaces

m3

6.956 Per 10.0 m

Washer150x150x9

ss400

pieces13m3

6.016 Per 10.0 m

M24

pieces13

Nut

Figure 7.2. Standard cross-sectional view (left) and support pattern (right) of the standard section of an access tunnel in the CII section.
45– Tohoku ILC Civil Engineering Plan –H-125

Shotcrete

Central drainage (excavation)

3.0

65.169 Per 1.0 m
1 for upper
Per 1.2 m
half

Steel arch support

Central drainage (drainpipe)

LengthRock bolt
Circumferentialdirection
1.5

46– Tohoku ILC Civil Engineering Plan –Rock Bolts L = 4.0 m(a yield strength of 176.5 kN or more)

Shotcrete

Steel Support
H-125 (Upper/Lower Half)

Lining Shotcrete

Wire Net(Upper Half)

Floor SlabCentralDrainage
Lining Shotcretet = 150 mm (18 N/mm2)
Shotcretet = 150 mm (18 N/mm2)

Table of unit quantities
Name

Table of specifications
Specification

Cross section of excavation(design)
Cross section of excavation (payAn outbreak of 17 cm
line)

Unit

Quantity

Remarks2

61.956 Per 1.0 m

m2

65.603 Per 1.0 m

m

1 for
upper/lower Per 1.0 m
half

H-125

units

Shotcrete

t=150

m2

Rock bolt

L = 4.0 m, a yield strength ofpieces
17.65 kN or more

Shot lining

t=150

m2

20.714 Per 1.0 m

Lining concrete

t=300

m

3

- Per 1.0 m

Roadbed concrete

t=400

m3

3.1 Per 1.0 m

Central drainage (drainpipe)

Φ300 (perforated pipe)m

10 Per 10.0 m

m3

6.956 Per 10.0 m

m3

6.016 Per 10.0 m

Central drainage (filter)s-20

Upper half Lower half

1.0

H-125

Lining thickness
Shot
thickness

H-125

Wire net

Shot
liningArch/sidewall

AssistancemethodInvert15 Upper half

15

-

-

Unit
m2/m

Quantity
20.713

Remarks

Unit

Quantity

Remarks-

Table of the amount of a shot material
Name
Shotcrete

20.713 Per 1.0 m

Dimension
t=150

Standard
σ28=18N/mm2

7Central drainage (excavation)

Steel arch support
Lengthdirection

16 Per 1.0 m

Table of the quantity of rock bolt materials
NameDimension

Rock bolt

L=4,000

WasherNut

150x150x9Standard
A yield strength of
17.65 kN or more
ss400
M24

pieces16 Mortar adheres to all surfaces

piecespieces16
16

Figure 7.3. Standard cross-sectional view (left) and support pattern (right) of the standard section of an access tunnel in the DI section.

Access Tunnels and Access Hall

Steel arch support

Rock bolt
Circumfere
Lengthntial
direction
4.0
1.2

Shotcrete
Lining Concretet = 350 mm withreinforcing bars

Lining ShotcreteRock Bolts
L = 4.0 m (a yield strength of
176.5 kN or more)
Steel Support
H-200 (Upper/Lower Half)

Wire Net(Upper/Lower
Half)

Floor
Slab
LiningShotcrete
InvertConcrete

7.1 Design specifications

Impregnation Long-sized Steel Pipe Tip
Receiving Work
L = 12.5 m (Improved Length) at 60 cm

InvertConcrete

CentralDrainage* Reinforcement Iron Bar: 50 kg/m3

Table of unit quantities

Table of specifications

Name

Specification

Cross section of excavation(design)
Cross section of excavation (payAn outbreak of 17 cm
line)

Unit

86.425 Per 1.0 m

m2

90.967 Per 1.0 m

units

Shotcrete

t=250

m2

Rock bolt

L = 4.0 m, a yield strength ofpieces
17.65 kN or more

1 forupper/lower Per 1.0 m
half
23.448 Per 1.0 m
10 Per 1.0 m

m2- Per 1.0 m

Length4.0

Steel arch support
Lengthdirection

1.2

1.0

Name
Shotcrete

Dimension

Name

Dimension

m3

15.202 Per 1.0 m

Roadbed concrete

t=400

m3

3.1 Per 1.0 m

Rock bolt

L=4,000

Central drainage (drainpipe)

Φ300 (perforated pipe)m

10 Per 10.0 m- Per 10.0 m

WasherNut

150x150x9m3
m3

6.016 Per 10.0 m

s-20

25

Upper/low
er half

-

Unit
m2/m

Quantity
23.448Remarks

Unit

Quantity

Remarks

H-200

Shot
liningArch/sidewall
300

InvertAssistancemethod500

AGF

Standard
t=250 σ28=18N/mm2

Table of the quantity of rock bolt materials

t = 300, invert with t = 500

Central drainage (filter)

H-200

Wire net

Table of the amount of a shot material

Lining concreteCentral drainage (excavation)

Upper half Lower half

Lining thickness
Shot
thickness

Standard
A yield strength of
17.65 kN or more
ss400
M24

pieces10 Mortar adheres to all surfaces

piecespieces10
10

Table of the quantity of an AGF material
Circumfere
ntial
direction
12.5m
@6cm

Improved
lengthDiameter Thicknessof a steel
of a steel
pipe
pipe
@6.0m
φ114.3t=6.0

Lengthdirection

Unit
piecesQuantity

Remarks

15 Impregnation method

Figure 7.4. Standard cross-sectional view (left) and support pattern (right) of the standard section of an access tunnel in the DIII section.
47– Tohoku ILC Civil Engineering Plan –H-200

Rock bolt
Circumfere
ntial
direction

Remarksm2

Steel arch support

Shot lining

Quantity

48– Tohoku ILC Civil Engineering Plan –Rock Bolts
L = 3.0 m (a yield strength of
117.7 kN or more)
Shotcrete

Lining Shotcrete

Floor
Slab

CentralDrainage
Lining Shotcretet = 100 mm (18 N/mm2)
Shotcretet = 100 mm (18 N/mm2)

Table of unit quantities
Name

Table of specifications
Specification

Cross section of excavation(design)
Cross section of excavation (payAn outbreak of 22 cm
line)

Unit

Quantity

Remarks

2

81.973 Per 1.0 m

m2

87.313 Per 1.0 m

m

Steel arch support

H-125

units

Shotcrete

t=100

m2

Rock bolt

L = 3.0 m, a yield strength ofpieces117.7 kN or moreRock bolt
Circumfere
Lengthntial
direction
3.0
1.5

Steel arch support
Lengthdirection
1.5

23.614 Per 1.0 m

Name
Shotcrete

Dimension-Standard
σ28=18N/mm2

t=100

t=100

m2

t=300

m3

- Per 1.0 m

Roadbed concrete

t=400

m3

3.9 Per 1.0 m

Central drainage (drainpipe)

Φ300 (perforated pipe)m

10 Per 10.0 m

Rock bolt

L=3,000

m3

6.956 Per 10.0 m
6.016 Per 10.0 m

WasherNut

150x150x9

m3

10

-

10

AssistancemethodInvert
-

-

-

Unit
m2/m

Quantity

Remarks

23.61423.614 Per 1.0 m

7

Table of the quantity of rock bolt materials
NameDimensionStandard
A yield strength of
117.7 kN or more
ss400
M24

Unit
piecesQuantity

Remarks
Mortar adheres to all surfaces

piecespiecesFigure 7.5. Standard cross-sectional view (left) and support pattern (right) of the emergency parking zone section of an access tunnel and the common
section of an access tunnel connecting the detector hall and damping rings in the CI section.

Access Tunnels and Access Hall

s-20

-

Arch/sidewall

Table of the amount of a shot material

15 Per 1.5 m

Lining concreteCentral drainage (filter)

Upper half Lower halfShotliningWire net- Per 1.5 m

Shot lining

Central drainage (excavation)

Lining thickness
Shot
thickness

7.1 Design specifications

Rock Bolts
L = 3.0 m (a yield strength of
176.5 kN or more)
Shotcrete
Steel Support
H-125 (Upper Half)

Lining Shotcrete

Floor
Slab

CentralDrainage
Lining Shotcretet = 150 mm (18 N/mm2)
Shotcretet = 100 mm (18 N/mm2)

Table of unit quantities

Table of specifications

Name

Specification

Cross section of excavation(design)
Cross section of excavation (payAn outbreak of 20 cm
line)

Unit
m

2

m2

Quantity

Remarks

83.506 Per 1.0 m
88.406 Per 1.0 m
1 for upper
Per 1.2 m
half

H-125

units

Shotcrete

t=100

m2

Rock bolt

L = 3.0 m, a yield strength ofpieces
17.65 kN or more

Shot lining

t=100

m2

Lining concrete

t=300

m3

- Per 1.0 m

Roadbed concrete

t=400

m3

3.9 Per 1.0 m

Central drainage (drainpipe)

Φ300 (perforated pipe)

Central drainage (excavation)
Central drainage (filter)s-20

23.866 Per 1.0 m
15 Per 1.2 m

Steel arch support
Lengthdirection

Lining thickness

Upper half Lower half

1.2

H-125

Shot
thickness-ShotliningWire net

10-

Arch/sidewall
15

AssistancemethodInvert---Table of the amount of a shot material
Name
Shotcrete

DimensionStandard
σ28=18N/mm2

t=100

Unit
m2/m

Quantity

Remarks

23.86635.799 Per 1.0 m

m

10 Per 10.0 m

m3

6.956 Per 10.0 m

m3

6.016 Per 10.0 m

Table of the quantity of rock bolt materials
NameDimension

Rock bolt

L=3,000

WasherNut

150x150x9Standard
A yield strength of
17.65 kN or more
ss400
M24

Unit

Quantity

Remarks

pieces15 Mortar adheres to all surfaces

piecespieces15
15

Figure 7.6. Standard cross-sectional view (left) and support pattern (right) of the emergency parking zone section of an access tunnel and the common
section of an access tunnel connecting the detector hall and damping rings in the CII section.

49– Tohoku ILC Civil Engineering Plan –Steel arch support

Rock bolt
Circumfere
Lengthntial
direction
3.0
1.5

50

– Tohoku ILC Civil Engineering Plan –Shotcrete
Shotcrete
Steel Support
H-125 (Upper/Lower Half)

Lining Shotcrete
Lining Shotcrete

Floor
Slab

CentralDrainage

Lining Shotcretet = 150 mm (18 N/mm2)
Shotcretet = 150 mm (18 N/mm2)

Table of unit quantities

Table of specifications

Name
Specification
Cross section of excavation(design)
Cross section of excavation (payAn outbreak of 17 cm
line)
Steel arch support
H-125
Shotcrete
Rock bolt

s-20

m2

84.404 Per 1.0 m

m2

89.815 Per 1.0 m

units
m2

Rock bolt
Circumfere
ntial
direction
4.0
1.2

Remarks

1 forupper/lower Per 1.0 m
half
23.866 Per 1.0 m

pieces

20 Per 1.0 m

m2
m3
m3
m
m3
m3

23.866 Per 1.0 m- Per 1.0 m
3.9 Per 1.0 m
10 Per 10.0 m
6.956 Per 10.0 m
6.016 Per 10.0 m

LengthSteel arch support
Lengthdirection
1.0

Upper half Lower half
H-125

Lining thickness
Shot
thickness

H-125

Wire net

Shot
lining15 Upper half

Arch/sidewall
15

AssistancemethodInvert---Table of the amount of a shot material
Name
Shotcrete

Dimension
t=150

Standard
σ28=18N/mm2

Unit
m2/m

Quantity
23.866

Remarks

Quantity

Remarks

Table of the quantity of rock bolt materials
NameDimension

Rock bolt

L=4,000

WasherNut

150x150x9Standard
A yield strength of 17.65
kN or more
ss400
M24

Unit
pieces20 Mortar adheres to all surfaces

piecespieces20
20

Figure 7.7. Standard cross-sectional view (left) and support pattern (right) of the emergency parking zone section of an access tunnel and the common
section of an access tunnel connecting the detector hall and damping rings in the DI section.

Access Tunnels and Access Hall

Lining concrete
Roadbed concreteCentral drainage (drainpipe)
Central drainage (excavation)
Central drainage (filter)

Quantity

7

Shot lining

t=150
L = 4.0 m, a yield strength of
17.65 kN or more
t=150
t=300
t=400
Φ300 (perforated pipe)

UnitShotcrete
Lining Shotcrete
Lining Concretet = 350 mm withreinforcing bars

Rock Bolts
L = 4.0 m (a yield strengthof 176.5 kN or more)
Steel Support
H-200 (Upper/Lower Half)

7.1 Design specifications

Impregnation Long-sized Steel Pipe Tip
Receiving Work
L = 12.5 m (Improved Length) at 60 cm

Floor
Slab

Shotcrete
InvertConcrete

Table of unit quantities

Table of specifications

Name

Specification

Cross section of excavation(design)
Cross section of excavation (payAn outbreak of 17 cm
line)

Unit

m2

164.337 Per 1.0 m

Shotcrete

t=250

m2

Rock bolt

L = 4.0 m, a yield strength ofpieces
17.65 kN or more

1 forupper/lower Per 1.5 m
half
26.137 Per 1.0 m- Per 1.0 m

3

16.945 Per 1.0 m

t = 300, invert with t = 500m

Roadbed concrete

t=400

m3

3.9 Per 1.0 m

Central drainage (drainpipe)

Φ300 (perforated pipe)m

10 Per 10.0 m

s-20

4.0

1.2

Upper half Lower half

1.0

H-200

Lining thickness
hot
thickness

Wire net

250

Upper/low
er half

-

Unit
m2/m

Quantity
26.137

Remarks

Unit

Quantity

Remarks

H-200

Shot
liningArch/sidewall
300

InvertAssistancemethod500

AGF

Table of the amount of a shot material
Name
Shotcrete

Dimension
t=250Standard
σ28=18N/mm2

10 Per 1.5 m

m2Lining concreteCentral drainage (excavation)

LengthSteel arch support
Lengthdirection

m3- Per 10.0 m

m3

6.016 Per 10.0 m

Table of the quantity of rock bolt materials
NameDimension

Rock bolt

L=4,000

WasherNut

150x150x9Standard
A yield strength of
17.65 kN or more
ss400
M24

pieces10 Mortar adheres to all surfaces

piecespieces10
10

Table of the quantity of an AGF material
Circumfere
ntial
direction
12.5m
@60cm

Improved
lengthDiameter Thicknessof a steel
of a steel
pipe
pipe
@6.0m
φ114.3t=6.0

Lengthdirection

Unit
piecesQuantity
19

Remarks
Impregnation method

Figure 7.8. Standard cross-sectional view (left) and support pattern (right) of the common section of an access tunnel connecting the detector hall anddamping rings in the DIII section.
51– Tohoku ILC Civil Engineering Plan –unitsRock bolt
Circumfere
ntial
direction

Remarks154.438 Per 1.0 m

m

H-200

Shot lining

Quantity2

Steel arch support

Central drainage (filter)

InvertConcrete

Central Drainage* Reinforcement Iron Bar: 50 kg/m3

52– Tohoku ILC Civil Engineering Plan –Rock Bolts
L = 4.0 m (a yield strength of
176.5 kN or more)

Lining Shotcrete
Shotcrete

Shotcrete
Lining Shotcrete

Table of unit quantities

Table of specifications

Name

Specification

Cross section of excavation(design)
Cross section of excavation (payOutbreak
line)

Unit

Quantity

Remarks
Length2222.766 Per 1.0 m

m2

231.213 Per 1.0 m

m

units

t=150

m2

- Per 1.5 m

Rock bolt

L = 4.0 m, a yield strength ofpieces
17.65 kN or more

Shot lining

t=150

m3

Lining concrete

t=300

m3

- Per 1.0 m

Roadbed concrete

t=400

m3

7.9 Per 1.0 m

37.573 Per 1.0 m

1.5

-

Shot
thickness-ShotliningWire net

15-

Arch/sidewall
15

AssistancemethodInvert--Table of the amount of a shot material
Name

Per 1.5 m

Lining thickness

Upper half Lower half

Shotcrete

DimensionStandard
σ28=18N/mm2

t=150

Unit
m2/m

Quantity

Remarks

37.57337.573 Per 1.0 m

Table of the quantity of rock bolt materials
NameDimension

Rock bolt

L=4,000

WasherNut

150x150x9-Standard
A yield strength of 17.65
kN or more
ss400
M24

Unit

Quantity

Remarks

pieces31 Mortar adheres to all surfaces

piecespieces31
31

Figure 7.9. Standard cross-sectional view (left) and support pattern (right) of an access hall (He dome).

Access Tunnels and Access Hall

H-125

Shotcrete

Steel arch support
Lengthdirection

7

Steel arch support

Rock bolt
Circumfere
ntial
direction
4.0
1.5

7.1 Design specifications

Rock Bolts
L = 4.0 m (a yield strength of
176.5 kN or more)

Lining Shotcrete
Shotcrete

Shotcrete
Lining Shotcrete

Table of unit quantities

Table of specifications

Name

Specification

Cross section of excavation(design)
Cross section of excavation (payOutbreak
line)

Unit

Quantity

Remarks2

161.088 Per 1.0 m

m2

168.541 Per 1.0 m

m

H-125

units

- Per 1.5 m

Shotcrete

t=150

m2

Rock bolt

L = 4.0 m, a yield strength ofpieces
17.65 kN or more

Shot lining

t=100

m3

Lining concrete

t=300

m3

- Per 1.0 m

Roadbed concrete

t=400

m3

5.5 Per 1.0 m

33.062 Per 1.0 m
27 Per 1.5 m

Steel arch support
Lengthdirection

Lining thickness

Upper half Lower half

1.5

-

Shot
thickness-ShotliningWire net

15-

Arch/sidewall
15

AssistancemethodInvert---Table of the amount of a shot material
Name
Shotcrete

DimensionStandard
σ28=18N/mm2

t=150

Unit
m2/m

Quantity

Remarks

33.06233.062 Per 1.0 m

Table of the quantity of rock bolt materials
NameDimensionStandard

Unit

Quantity

Remarks

Rock bolt

L=4,000

A yield strength of
17.65 kN or more

pieces27 Mortar adheres to all surfaces

Washer150x150x9

ss400

pieces27

M24

pieces27

Nut

Figure 7.10. Standard cross-sectional view (left) and support pattern (right) of an access hall (S/E/M dome).
53– Tohoku ILC Civil Engineering Plan –Steel arch support

Rock bolt
Circumfere
Lengthntial
direction
4.0
1.5

54

7

Access Tunnels and Access Hall

7.2 Construction plan
7.2.1 Outline of the plan
The construction plan was created in accordance with the Civil Engineering Estimation Standards of the
Ministry of Land, Infrastructure, Transport, and Tourism. For the construction of an access hall for an He
dome, however, its support pattern, construction quantity per unit, and other matters were planned by
setting the cycle time of construction in accordance with the above estimation standards because theconstruction requires a large cross section (222 m2) of excavation.
The outline of the plan is as follows:•

Concepts of pay lines (for outbreak, extra shot, and extra lining) are in accordance with theabove estimation standards.

•

Standards on excavating equipment (drill carriages, wheel loaders, concrete guns, concrete
breakers, and dump trucks) are in accordance with the above estimation standards.

•

Standards on shotcrete, rock bolts, steel support, and other materials are in accordance with theabove estimation standards.

•

Excavation muck is assumed to be placed near a pithead temporarily, and then transported
secondarily to a place 10 km away from the pithead by 10-ton dump trucks for disposal. Since
the appearance of mineralized muck is assumed to be less likely according to the results ofgeological surveys, we do not consider the costs and facilities for mineralized muck disposal. If
mineralized muck appears during construction, it is disposed of appropriately.

7.2.2 Preparation of pithead yards
For the preparation of pithead yards, we calculated the amount of cutting (88,000 m 3) and banking (2,200m3) for AS-12 as a typical place with average topography (ground surface inclination)6), and assumed thesame amount of cutting and banking for yards of other points. AS-DR and AS-DH were determined tocontain two temporary facilities in the same yard.

7.2.3 Excavation method
A blasting method is applied to excavate places other than pithead sections. For blasting, we have decided
to apply a full face method with auxiliary bench cut for pattern C and a top heading and bench cut method
for pattern D.
For the excavation of an access hall for an He dome, a top heading raising-cut and two-layered benchmethod was assumed.

6

AS-12 is a pithead yard that was planned for a length of 30 km. Though the present project does not include this pithead, it does have average
topography.

– Tohoku ILC Civil Engineering Plan –7.2 Construction plan

55

7.2.4 Temporary facility plan
Outline of the temporary facility plan is as follows:•

Types of temporary facilities on the pithead yards are in accordance with the above estimation
standards.

•

Temporary facilities in the shafts are in accordance with the above estimation standards.
However, some parts of the specifications, such as electric equipment, were planned.

•

Turbid water treatment facilities were planned by assuming the amount of treatment.

7.2.5 Process plan
Processes for each access tunnel were calculated for each cross section corresponding to a rock mass classon the basis of construction quantity per unit stated in the above estimation standards.
Access halls and the accelerator tunnel were assumed to be excavated at the same time after an accesstunnel reaches the designated depth of the accelerator tunnel. Each pithead yard can ensure an area
necessary for operation for the relevant facings. Excavation and lining shot are conducted before drainage(excavating the central drainage, installing perforated pipes, and backfilling broken stones) is performed;
the floor slab concrete is then poured.
For the construction period for a large cross section of excavation for an access hall for an He dome, there
are no methods of calculating its construction quantity per unit according to cycle time calculation at present.
Accordingly, we calculated its cycle time and then the processes by applying the Civil Engineering
Estimation Standards of the Ministry of Land, Infrastructure, Transport, and Tourism in the 2005 fiscal
year, which was the last fiscal year when the calculation method of construction quantity per unit according
to cycle time calculation was applicable.
In addition, the present construction process plan does not include the following activities: the new
installation of roads from ordinary roads to pithead yards for construction; the widening and reinforcementof existing roads; and the rebuilding and new installation of bridges. This is because these activities are
assumed to be conducted in advance by other construction work as necessary. Similarly, the present
construction process plan does not include the periods necessary for obtaining lands for pithead yards, roads
for construction, surplus soil disposal facilities, and other purposes.
Figure 7.11 shows a table of processes for the access tunnels and access halls. Construction periods dependon the lengths of the access tunnels; the shortest period was 33 months (AS+8) and the longest one was 54
months (AS-10).

– Tohoku ILC Civil Engineering Plan –56– Tohoku ILC Civil Engineering Plan –Length Period(Months)
Preparation 5monthsTemporaryfacility

Drainage

Excavation and lining shot

Floor slab
Excavation of the accelerator
tunnel starts

Access tunnel
Access hall

Preparation 5monthsTemporaryfacility

Excavation and lining shot

Drainage

Floor slab
Excavation of the accelerator
tunnel starts

Access tunnel
Access hall

Preparation 5monthsTemporaryfacility

Excavation and lining shot

Drainage

Access tunnel

Floor slab
To DR

Access hall
DivergingTemporaryfacility

Excavation and lining shot

Drainage Floor slab
To DH

Access tunnel

Preparation 5monthsTemporaryfacility

Excavation and lining shot

Preparation 5monthsTemporaryfacility

Excavation and lining shot

Access tunnel

Drainage Floor slab
Excavation of the accelerator
tunnel starts

Access hall

7

Drainage

Floor slab
Excavation of the accelerator
tunnel starts

Access hall

Figure 7.11. Processes for the access tunnels and access halls.

Access Tunnels and Access Hall

Access tunnel

57

8 Accelerator Tunnel

8.1 Design specifications
8.1.1 Rock mass classes
The seismic exploration shows that an elastic wave speed at the altitude of the accelerator tunnel was 4.5
km/s or more in places other than the cross points of rivers, and the slowest speed was 2 km/s measured at
the cross point of Satetsu River. Rock mass classes were determined to be CI for the whole site withreference to the Table of Rock Mass Class in the Civil Engineering Estimation Standards of the Ministryof Land, Infrastructure, Transport, and Tourism.

8.1.2 Dimensions and structures of the accelerator tunnel
The accelerator tunnel has the following four types of cross sections:
1.

Main linear accelerator tunnels: a width of 9.5 m and a height of 5.5 m

2.

BDS beam tunnels: a width of 8.0 m and a height of 5.0 m

3.

BDS service tunnels and loop sections at both ends: a width of 4.5 m and a height of 4.0 m

4.

Damping ring tunnel: a width of 5.5 m and a height of 4.7 m

In addition, the following dimensions are determined to be included:•

10 widening sections are included for all accelerator-related tunnels; each section has a widthof 11 m, a height of 5.5 m, and a length of 50 m.

•

For the main linear accelerator tunnels, 76 reversal pits are included (at 200-m intervals in theoverall length of 15,287 m); each of the pits has the same cross section as the tunnel (a width of
9.5 m and a height of 5.5 m) and a length of 20 m.

Table 8.1 shows the total lengths of the tunnels.

– Tohoku ILC Civil Engineering Plan –58

8Accelerator Tunnel

Table 8.1. List of the accelerator-related tunnels
Excavation section
Main linear accelerator tunnels
BDS beam tunnels
BDS service tunnels
Damping ring tunnel
Loop sections at both ends
Widening sections
Reversal pits

Width
(m)
9.5

Height(m)
5.5

Total length(m)
15,287

8.0
4.5
5.5
4.5
11.0
9.5

5.0
4.0
4.7
4.0
5.5
5.5

5,850
5,850
3,725
346
500
1,520

We determined standard cross-sectional views and support patterns corresponding to rock mass class andexcavation cross sections in accordance with the Civil Engineering Estimation Standards of the Ministryof Land, Infrastructure, Transport, and Tourism. Figures 8.1 to 8.4 show the standard cross-sectional views
and support patterns of the tunnels7).
For cross points of rivers with a thin overburden, we additionally consider that they require other detailed
geological surveys and design examination.

7

As described in Chapter 1, the main linear accelerator tunnels require a width of 9.5 m. As described in Chapter 5, the result of the examination
for a width of 9 m (Figure 8.1) was converted on the basis of a cross section for the evaluation of costs and excavation processes (per month); forthe evaluation of roadbed processes, it was converted on the basis of a tunnel width.

– Tohoku ILC Civil Engineering Plan –8.1 Design specifications

Shotcrett = 100 mm (18N/mm2)

Rock Bolts
L = 3.0 m (a yield strength of
176.5 kN or more)

Table of specifications:Rock bolt
Circumferential Length
direction
direction
1.5
1.5

LengthTable of unit quantities:

3.0

Name

Specification

Quantitym2

51.941

Per 1.00 m

RemarksName

An outbreak of 22 cm

m2

56.044

Per 1.00 m

Shotcrete

Shotcretet = 100 mm

m2

26.984

Per 1.50 m

Rock bolt

L = 3.0 m, a yield strength of
176.5 kN or more

pieces12

Per 1.50 m

Lining concretet = 300 mm

m

5.255

Per 1.00 m

Roadbed concretet = 400 mm

m2

3.500

Per 1.00 m

High-density polyethylene
pipe φ300 (perforated pipe)

m

10.0

Per 10.0 m

m3

6.956

Per 10.0 m

m3

6.016

Per 10.0 m

Central drainage (drain pipe)
Central drainage (excavation)
Central drainage (filter)

S-20

Lower
half
-

10

Lining thickness(cm)

Deformation margin (cm)Arch

InvertUpper half

30

-

Unit

Quantitym2

26.684

Unit

Quantity-

Table of shot material:
Standard
σ28=18N/mm2

t＝100

Table of rock bolt materials:

Invert-Remarks

Per P = 1.50 m

DimensionStandard

Rock bolt

L=3,000

A yield strength of
176.5 kN or more

pieces12

Washer150x150x9

SS400

pieces12

M24

pieces

12

Nut

0

Lower
half
0

Per P = 1.50 m

Dimension

Name
2

Upper
half
-

Shot
thickness(cm)

Remarks
Mortar adheres to all surfaces

Figure 8.1. Standard cross-sectional view (left) and support pattern (right) of a main linear accelerator tunnel and a reversal pit (as described in Chapter 5,
the result of the examination for a width of 9 m was converted on the basis of the cross section and tunnel width).
59– Tohoku ILC Civil Engineering Plan –Unit

Cross section of excavation(design)
Cross section of excavation (payline)

Steel support

60– Tohoku ILC Civil Engineering Plan –ShotcretRock Bolts
L = 3.0 m (a yield strength of
176.5 kN or more)

Table of specifications:Rock bolt
Circumferential Length
direction
direction
1.5
1.5

LengthTable of unit quantities:

3.0

Name
Cross section of excavation(design)
Cross section of excavation(pay line)

Specification

Unit

Quantity2

41.851

Per 1.00 m

Name

m2

45.540

Per 1.00 m

Shotcrete2

24.163

Per 1.50 m

11

Per 1.50 m

m
An outbreak of 22 cm

Remarkst = 100 mm

m

Rock bolt

L = 3.0 m, a yield strength of
176.5 kN or more

piecesLining concretet = 300 mm

m2

4.691

Per 1.00 m

Roadbed concretet = 300 mm

m2

2.300

Per 1.00 m

High-density polyethylene
pipe φ300 (perforated pipe)

Central drainage (excavation)
Central drainage (filter)

10.0

Per 10.0 m

3

5.839

Per 10.0 m

m3

4.899

Per 10.0 m

m
S-20

10

Deformation margin (cm)Arch

InvertUpper half

30

-

Unit

Quantitym2

24.163

Unit

Quantity-

Table of shot material:
Standard
σ28=18N/mm2

t＝100

Table of rock bolt materials:

Lower
half
0

Invert-Remarks

Per P = 1.50 m

DimensionStandard

Rock bolt

L=3,000

A yield strength of
176.5 kN or more

pieces11

Washer150x150x9

SS400

pieces11

M24

pieces11

Nut

0

Per P = 1.50 m

Dimension

Name

m

Lower
half
-

Lining thickness(cm)

Remarks
Mortar adheres to all surfaces

Figure 8.2. Standard cross-sectional view (left) and support pattern (right) of a BDS beam tunnel.

Accelerator Tunnel

Central drainage (drain pipe)

Upper
half
-

Shot
thickness(cm)

8

Shotcrete

Steel support

8.1 Design specifications

ShotcretRock Bolts
L = 3.0 m (a yield strength of
176.5 kN or more)

Table of specifications:Rock bolt
Circumferential Length
direction
direction
1.5
1.5

LengthTable of unit quantities:

3.0

Name

Specification

Unit

Quantity2

21.896

Per 1.00 m

Name

m2

24.054

Per 1.00 m

Shotcrete2

18.167

Per 1.50 m

8Per 1.50 m

m
An outbreak of 17 cm

Remarks

Shotcretet = 100 mm

m

Rock bolt

L = 3.0 m, a yield strength of
176.5 kN or more

piecesLining concretet = 300 mm

m2

3.492

Per 1.00 m

Roadbed concretet = 300 mm

m2

1.250

Per 1.00 m

Central drainage (drain pipe)

High-density polyethylene
pipe φ300 (perforated pipe)

Central drainage (excavation)
Central drainage (filter)

10.0

Per 10.0 m

3

5.668

Per 10.0 m

m3

4.727

Per 10.0 m

m
S-20

Lower
half
-

10

Lining thickness(cm)

Deformation margin (cm)Arch

InvertUpper half

30

-

Unit

Quantitym2

18.167

Unit

Quantity-

Table of shot material:
Standard
σ28=18N/mm2

t＝100

Table of rock bolt materials:

Lower
half
0

Invert-Remarks

Per P = 1.50 m

DimensionStandard

Rock bolt

L=3,000

A yield strength of
176.5 kN or more

pieces8

Washer150x150x9

SS400

pieces8

M24

pieces8

Nut

0

Per P = 1.50 m

Dimension

Name

m

Upper
half
-

Shot
thickness(cm)

Remarks
Mortar adheres to all surfaces

Figure 8.3. Standard cross-sectional view (left) and support pattern (right) of a BDS service tunnel and a loop section at both ends.
61– Tohoku ILC Civil Engineering Plan –Cross section of excavation(design)
Cross section of excavation (payline)

Steel support

62– Tohoku ILC Civil Engineering Plan –ShotcretRock Bolts
L = 3.0 m (a yield strength of
176.5 kN or more)

Table of specifications:Rock bolt
Circumferential Length
direction
direction
1.5
1.5

LengthTable of unit quantities:

3.0

Name
Cross section of excavation(design)
Cross section of excavation (payline)

Specification

Unit

Quantity2

29.761

Per 1.00 m

Name

m2

32.254

Per 1.00 m

Shotcrete2

21.123

Per 1.50 m

9Per 1.50 m

m
An outbreak of 17 cm

Remarkst = 100 mm

m

Rock bolt

L = 3.0 m, a yield strength of
176.5 kN or more

piecesLining concretet = 300 mm

m2

4.083

Per 1.00 m

Roadbed concretet = 300 mm

m2

1.550

Per 1.00 m

High-density polyethylene
pipe φ300 (perforated pipe)

Central drainage (excavation)
Central drainage (filter)

10.0

Per 10.0 m

3

7.882

Per 10.0 m

m3

6.942

Per 10.0 m

m
S-20

10

Deformation margin (cm)Arch

InvertUpper half

30

-

Unit

Quantitym2

21.123

Unit

Quantity-

Table of shot material:
Standard
σ28=18N/mm2

t＝100

Table of rock bolt materials:

Lower
half
0

Invert-Remarks

Per P = 1.50 m

DimensionStandard

Rock bolt

L=3,000

A yield strength of
176.5 kN or more

pieces9

Washer150x150x9

SS400

pieces9

M24

pieces9

Nut

0

Per P = 1.50 m

Dimension

Name

m

Lower
half
-

Lining thickness(cm)

Remarks
Mortar adheres to all surfaces

Figure 8.4. Standard cross-sectional view (left) and support pattern (right) of the damping ring tunnel.

Accelerator Tunnel

Central drainage (drain pipe)

Upper
half
-

Shot
thickness(cm)

8

Shotcrete

Steel support

8.1 Design specifications

Rock Bolts
L = 3.0 m (a yield strength of
176.5 kN or more)

Shotcret

Table of specifications:Rock bolt
Circumferential Length
direction
direction
1.5
1.5

Length
3.0

Upper
half
-

Lower
half
-

Shot
thickness(cm)
10

Lining thickness(cm)

Deformation margin (cm)InvertUpper half

30

-

Unit

Quantitym2

29.476

Unit

Quantity-

Name
Specification

Unit

Quantity

Cross section of excavation(design)
Cross section of excavation (payAn outbreak of 22 cm
line)

Name

m2

62.725

Per 1.00 m

Remarksm2

67.194

Per 1.00 m

2

29.476

Per 1.50 m

13

Per 1.50 m

Shotcretet = 100 mm

m

Rock bolt

L = 3.0 m, a yield strength of
176.5 kN or more

piecesLining concretet = 300 mm

m2

5.753

Per 1.00 m

Roadbed concretet = 400 mm

m2

4.300

Per 1.00 m

Central drainage (drain pipe)

High-density polyethylene
pipe φ300 (perforated pipe)

Shotcrete

Central drainage (excavation)
S-20

m

10.0

Per 10.0 m

m3

6.956

Per 10.0 m

m3

6.016

Per 10.0 m

Standard
σ28=18N/mm2

t＝100

Table of rock bolt materials:-

Remarks

Per P = 1.50 m

DimensionStandard

Rock bolt

L=3,000

A yield strength of
176.5 kN or more

pieces13

Washer150x150x9

SS400

pieces13

M24

pieces13

Nut

InvertPer P = 1.50 m

Dimension

Name

0

Lower
half
0

Figure 8.5. Standard cross-sectional view (left) and support pattern (right) of a widening section.

Remarks
Mortar adheres to all surfaces

63– Tohoku ILC Civil Engineering Plan –Arch

Table of shot material:

Table of unit quantities:

Central drainage (filter)

Steel support64

8

Accelerator Tunnel

8.2 Construction plan
8.2.1 Outline of the plan
The construction plan was created in accordance with the Civil Engineering Estimation Standards of the
Ministry of Land, Infrastructure, Transport, and Tourism. Table 8.2 lists the construction specifications of
the excavation sections. However, the above standards state only those for a one-way tunneling length of
up to 2,500 m. For cases where the one-way tunneling length exceeds 2,500 m, we examined the plan byseparately considering an increase in the number of dump trucks, tunnel special processes, and other matters.

Table 8.2. List of the construction specifications of the accelerator-related tunnels

Excavation section
Main linear accelerator
tunnels
BDS beam tunnels
BDS service tunnels
Damping ring tunnel
Loop sections at both ends

Cross
section(m2)

Applicable cross Excavatio
sectionn method(m2)

Mucking
methodExcavation
speed(m/month)

55.75

65.0

NATM

Tire

106

41.85
21.90
29.76
21.90

40.0
20.0
30.0
20.0

NATM
NATM
NATM
NATM

Tire
Rail
Rail
Rail

124
73
62
73

In addition, outlines of the plan are as follows:•

Temporary facility yards for tunnels are to be used continuously from the construction of theaccess tunnels. Additionally, we do not consider the restoration of the temporary facility yards.

•

Excavation muck is assumed to be placed near a pithead temporarily, and then transported
secondarily to a place 10 km away from the pithead by 10-ton dump trucks to be disposed of.
Since the appearance of mineralized muck is assumed to be less possible according to the resultsof geological surveys, we do not consider costs and facilities for mineralized muck disposal. If
mineralized muck appears during construction, it is disposed of appropriately.

8.2.2 Outline of the construction process plan
The construction process plan was according to the following conditions:Excavation from AH+10/AH-10
1.

A main linear accelerator tunnel is excavated in the two directions simultaneously to one end
and the center.

– Tohoku ILC Civil Engineering Plan –8.2 Construction plan65

2.

After the excavation reaches the end, a loop section is excavated.

3.

Lining will be completed three months after the completion of the excavation.

4.

After the lining is completed, roadbed concrete is constructed at a speed of 21 m/day
simultaneously in the two directions to the end and center.

Excavation from AH+8/AH-8
1.

The following three routes of excavation are conducted simultaneously: a main linear
accelerator tunnel to one end, and a BDS beam tunnel and a BDS service tunnel to the center.

2.

Lining will be completed three months after the completion of excavation.

3.

After the lining of these tunnels is completed, roadbed concrete is constructed at a speed of 21
m/day simultaneously in the two directions to the end and center.

Excavation of the damping ring tunnel
1.

Four faces are excavated simultaneously.

2.

The lining will be completed three months after the completion of the simultaneous excavation.

3.

After the lining is completed, the roadbed concrete is constructed at a speed of 21 m/day
simultaneously for the four places.

In addition, we considered applying both a tire method for the main linear accelerator tunnels and a rail
method for the loop sections as excavation methods from AH+10/AH-10 to the ends. The details of these
excavation methods are supposed to require re-examination after construction methods and processes are
determined.
Figure 8.6 shows the accumulated construction period from the beginning of the construction of the accesstunnels. Since the period for starting the construction of the accelerator tunnel depends on the construction
period of the access tunnels, the construction period of the accelerator tunnel is decided by the lengths of
the access tunnels. One access tunnel is the longest with a route where excavation starts from AS-10 to a
RTML at one end; this route had the longest accumulated construction period of 90.8 months.

– Tohoku ILC Civil Engineering Plan –66– Tohoku ILC Civil Engineering Plan –(Unit)
LengthConstruction period(month)VerticalsectionStraight
section4 facings
4 facings

CurvedsectionParallelSection length
Divided section length

ParallelShape of excavation cross section
Semicylindrical shape (106.2 m/month)(month)DR (62 m/month)(month)RTML (73 m/month)(month)Excavation period(month)Lining(conducted 3 months after the excavation)(month)Roadbed construction(ML 418 m/month, BDS 496 m/month)
Curtain wall construction(month)(PC block 239 m/month)
Overall period(month)(year)

Figure 8.6. Processes of the accelerator tunnel.
8
Accelerator Tunnel

67

9 Detector Hall and Peripheral Tunnels

9.1 Design specifications
9.1.1 Rock mass classes
The results of the seismic exploration and boring surveys show that hard granite with a few fissures arewidely distributed at the depth where the detector hall is constructed. We regarded the relevant rock masses
as granite with classes B to CH with reference to the result of the geological surveys. In addition, there isan overburden of about 100 m.
For tunnels constructed around the detector hall, we regarded the rock mass class as CI, which is same asother accelerator-related tunnels.

9.1.2 Dimensions and structures of the detector hall and peripheral tunnels
The specifications of the detector hall and peripheral tunnels are as follows:1.

Detector hall:Space size: W25 m x L133 m x H42 m
Shape: Bullet shape (with an arch and a vertical wall), which has a mushroom-shaped shaft
through part (with ceiling concrete)●

The ceiling is finished with shotcrete, and construction finishing work is conducted
separately.

●

The building of a crane wall and bottom slab concrete is included.

2.

Main shaft: a diameter of 18 m and a depth of approximately 70 m

3.

Utility shaft: a diameter of 10 m and a depth of approximately 70 m

4.

Peripheral tunnel: a width of 8.0 m and a height of 7.5 m

5.

Peripheral tunnel: a width of 4.0 m and a height of 4.0 m– Tohoku ILC Civil Engineering Plan –Cross Section A-A

Cross Section B-B

68– Tohoku ILC Civil Engineering Plan –Plan View

Utility Hall Gable Wall

Main Shaft
Utility Hall Shaft

Cross Section D-D

Cross Section E-E

Cross Section C-C

Cross Section F-F
Utility Hall Shaft

9

Main Shaft

Detector Hall and Peripheral Tunnels

Figure 9.1. A schematic drawing of the detector hall and peripheral tunnels.

9.1 Design specifications

69

9.1.3 Design of support
Detector hallRock bolts, PS anchors, and shotcrete were planned to be applied to the support for the detector hall, withreference to the construction case of the Okawachi Power Station (in the Kanzaki District of Hyogo
Prefecture), which has a bullet shape the same as the detector hall and dimensions also similar to it.
In addition, we decided to support the loads of the main shaft and utility shaft connecting to the detector
hall with shearing resistance between the rock mass and support around the shafts and the detector hall. To
support shafts, the structure of the detector hall was planned as follows:•

The load applied from the main shaft to the detector hall is supported by lining concrete (withthe crown 1 m thick) poured into the arch connecting to the shaft and the side wall (with athickness of 3 m) of the detector hall.

•

The load from the utility shaft to the detector hall is supported by the gable wall connecting to
the shaft. Table 9.1 and Figures 9.2 to 9.4 show standard support patterns.

Table 9.1. List of standard support patterns of the detector hall.
Rock bolt
Part(i)
Gable of (i)(ii)
Gable of (ii)(iii)
Gable of (iii)

PS anchor

5.0

Yield
strength(kN)
120

Circumferential/
length direction
Interval (m)
2/2

5.0
5.0
5.0
5.0
5.0

120
120
120
120
120

2/2
2/2
2/2
2/2
2/2

Length
(m)

(ii)

15.0

Circumferential/
length direction
Interval (m)
4/4

15.0
15.0
15.0
15.0
15.0

4/4
4/4
4/4
4/4
4/4

Length(m)

Shotcrete
σck = 18 N/mm2
Thickness
(cm)
24

24
24
24
24
24

(iii)

(i)
(ii)

(iii)

Tohoku ILC Civil Engineering Plan –70– Tohoku ILC Civil Engineering Plan –①-① (Standard
PS Anchors
Section)②-②
PS Anchors

Rock Bolts

Rock Bolts

Lining Concrete
Shotcrete
Shotcrete

PS Anchors
Rock Bolts
Rock Bolts

PS Anchors

Rock Bolt L = 15 m (n = Number)
PS Anchor L = 5 m (n = Number)
Shotcrete t = 24 cm
Rock Bolts

Figure 9.2. Standard support pattern (1) of the detector hall.

Detector Hall and Peripheral Tunnels

Legends

9

Location Image9.1 Design specifications

③-③

④-④
PS Anchors

Rock Bolts

Shotcrete

Shotcrete

PS Anchors
Rock Bolts

PS Anchors
Rock Bolts

71– Tohoku ILC Civil Engineering Plan –Figure 9.3. Standard support pattern (2) of the detector hall.

72– Tohoku ILC Civil Engineering Plan –

⑤-⑤

⑥-⑥

Rock Bolts

Rock Bolts

PS Anchors

PS Anchors

Shotcrete
Shotcrete

9Detector Hall and Peripheral Tunnels

Figure 9.4. Standard support pattern (3) of the detector hall.

9.1 Design specifications

73

Shaft
Support structures of the shafts were examined by applying the Road Tunnel Technical Standards for
similar cross-sectional dimensions because shafts are not covered by the Civil Engineering Estimation
Standards of the Ministry of Land, Infrastructure, Transport, and Tourism.

•

Since the main shaft has a large cross section with a diameter of 18 m, its support pattern wasdetermined in accordance with the standard support patterns for large cross-sectional tunnels in
the Design Guidelines of the East, Central, and West Nippon Expressway Company.

•

The support pattern of the utility shaft (with a diameter of 10 m) was determined in accordancewith the “Standard Support Patterns for Road Tunnels (with medium cross sections)” in the
Road Tunnel Technical Standards of the Japan Road Association.

Figure 9.5 shows the tunnel support patterns of the main shaft and utility shaft.
For the cross areas of the crown of the detector hall and the shafts, in addition, we consider that they require
other detailed examinations.

Peripheral tunnels
Standard support patterns of peripheral tunnels were in accordance with the Road Tunnel TechnicalStandards of the Japan Road Association, and determined to be the rock mass class of CI. Figure 9.6 shows
the support patterns of peripheral tunnels.

Tohoku ILC Civil Engineering Plan –74– Tohoku ILC Civil Engineering Plan –Main Shaft

Section CI

Section CI

Section CII

Section CII

Utility Shaft

Cross Section B-B' (Section CI)

Cross Section C-C' (Section CII)

Steel Support
Shotcrete

Rock Bolts

Shotcrete

Steel Support
Rock Bolts

Shotcrete

Rock Bolts

Figure 9.5. Standard support patterns of the main shaft and utility shaft.

Shotcrete

Detector Hall and Peripheral Tunnels

Steel Support

Steel Support

Rock Bolts

Cross Section D-D' (Section CI)

9

Cross Section A-A' (Section CII)

Cross Section B-B

Rock Bolts

9.1 Design specifications

Cross Section A-A

Primary Shotcrete

Secondary ShotcreteRock Bolts

Primary Shotcrete

Figure 9.6. Standard support patterns of peripheral tunnels.

75– Tohoku ILC Civil Engineering Plan –Secondary Shotcrete

76

9Detector Hall and Peripheral Tunnels

9.2 Construction plan
9.2.1 Outline of the construction
Applied construction methods were according to the following conditions:•

A full face method was applied for shaft excavation because no under-work pits are used for the
excavation.

•

The arch of the detector hall was constructed by a center drift advancing method after the shaftsare excavated, and a basement for the excavation of the arch is then installed under the shafts.
Since an access tunnel and peripheral tunnels reach the lower stage during the construction of
the body, mucking holes are made and a bench excavation method is applied for the construction.

•

Excavation muck from the arch is removed from the shafts, and that from the benches isremoved from a lower access tunnel.

•

Excavation muck is assumed to be placed near a pithead temporarily, and then transported
secondarily to a place 10 km away from the pithead by 10-ton dump trucks for disposal. Since
the appearance of mineralized muck is assumed to be less likely according to the results ofgeological surveys, we do not consider the costs and facilities for mineralized muck disposal. If
mineralized muck appears during construction, it is disposed of appropriately.

9.2.2 Outline of the construction process plan
For the excavation speed of a shaft, we determined 18.9 m/month for an initial liner section and 11.6
m/month for an NATM section with reference to construction work for the tunnel discharging facility gatehouse and other sections for the redevelopment of the Amagase Dam (in the Uji City of Kyoto Prefecture)(a depth of 49.9 m, a finished inner diameter of 24 m, and an excavation outer diameter of 26.4 m).
Figure 9.7 shows a list of the processes for the detector hall, shafts, and peripheral tunnels. Construction
period was estimated at 66 months.

– Tohoku ILC Civil Engineering Plan –2nd year

3rd year

4th year

5th year

6th year

Preparation of IP above-ground yards andconstruction of emporary facilities

8.0 months

Preparation of D/R access above-ground yards
and construction of temporary facilities

14.0 months
Construction of the D/R access tunnel

7th year
Remarks

9.2 Construction plan

1st year
Name of construction

8.0 months
D/R access tunnel
5.0 months
D/H connecting tunnel

10.0 months

10.0 months

Construction of the main shaft
Excavation of the pithead
Pithead protection concrete
Excavation of the NATM section

Construction of the test collision hall

10.0 months

Excavation of the arch

Mucking through theshaftsExcavation of the body17.0 months
15.0 months

Building concrete
Concrete for the sidewall and arch

10.0 months

Excavation of the pithead
Pithead protection concrete
Excavation of the NATM section

Construction of the assembly hall

Figure 9.7. Processes for the detector hall, shafts, and peripheral tunnels
77– Tohoku ILC Civil Engineering Plan –10.0 months
Construction of the utility shaft

79

10 Drainage Facilities

10.1 Requirements of the ILC accelerator for drainage facilities
10.1.1 Accelerator tunnel
The main linear accelerator tunnels, which contain accelerator bodies (cryomodules) using liquid helium,
are parallel to the geoid plane. In addition, the BDS tunnels (occupying approximately 6 km near the center)are determined to be “laser straight,” and have a falling gradient of approximately 1/2,000 towards thecenter. A drainage method is thus required to ensure the drainage of groundwater into the accelerator tunnel,
which is horizontal or has a very low inclination, out of the pits after beginning facility usage.

10.1.2 Drainage tunnel
Since the underground facility is scheduled to be constructed at an altitude of approximately 110 m in the
Tohoku ILC Civil Engineering Plan, drainage can be planned with gravitational flow by means of adrainage tunnel. Gravitational drainage through the drainage tunnel allows us to avoid full water damageof devices even in emergency cases such as long-term power failure.
Though examinations of the Global Design Effort do not include a drainage tunnel, the Tohoku ILC Civil
Engineering Plan examines this tunnel with the aim of avoiding the full water damage of devices even in
emergency cases such as long-term power failure.

10.1.3 Drainage system
Figure 10.1 shows a diagram of a drainage system after beginning facility usage.
Groundwater into the main linear accelerator tunnel is forced to be drained to the nearest access hall. Then,
it is forced to be drained from the access hall to the ground surface through an access tunnel by a pump.

– Tohoku ILC Civil Engineering Plan –

80

10

Gravitational Drainage(Gravity)

Drainage Facilities

Access Tunnel (-9%)

Forced Drainage (Pump)

Drainage Tunnel L = 4.3 km
The TDR does not include it.

Figure 10.1. A diagram of the drainage system of the underground facility after the beginningof facility usage.
Groundwater into the BDS tunnel is flown to the detector hall by gravity, or drainage is forced. Then, thedrainage is forced from the detector hall to the ground surface through an access tunnel by pump, or drained
through a drainage tunnel by gravity.

10.2 Design specifications
10.2.1 Condition of constant groundwater inflow rate
We assumed the constant groundwater inflow rate after the beginning of facility usage to be “0.8 m3/min/km”(see Chapter 4), estimated on the specific discharge of base flow and a groundwater-affected area.

10.2.2 Sectional drainage method in the accelerator tunnel
We assume the inclination necessary for drainage by gravitational flow to be 0.1% for the following
considerations. This value corresponds to the lower limit of laying inclination standard values of 1/100 to
1/1,000 for agricultural culvert pipes [8].
To lead groundwater in a main linear accelerator tunnel to the nearest access hall, a section length ofapproximately 2.5 km (a half of the distance between adjacent access halls) is required. If groundwater forthe maximum overall length of this section is drained by gravity, the difference of elevation necessary forensuring an inclination of 0.1% is 2.5 km x 0.1% = 2.5 m, which is excessive for the central drainage pipewith a diameter of 300 mm under the bottom slab of the accelerator tunnel.

– Tohoku ILC Civil Engineering Plan –10.2 Design specifications

81

If the maximum overall length is shortened from 2.5 km to “250 m,” the difference of elevation
corresponding to an inclination of 0.1% becomes 250 mm, which makes construction realistic. Thus, wehave determined the central drainage pipe to have an inclination of 0.1% alternately at 250m intervals, andmake groundwater flow to drainage pits installed at 500-m intervals by gravity (see “Cross Section A-A”
in Figure 10.2).
A vertical drainage ditch with an inclination of 0.1% is installed in the bottom slab of the accelerator tunnel,
and drainage tanks are installed at 500-m intervals. Groundwater flown from drainage pits to drainage tanks
is pumped up in the tanks by water pumps, and is then forced to flow to the nearest access halls while it is
led successively (see “Cross Section B-B” in Figure 10.2).
Figure 10.2 shows a schematic drawing of the drainage system in the accelerator tunnel. Note that the reteof groundwater inflow into a section 500 m in length is assumed to be 0.8 m3/min/km x 0.5 km x 130% =0.52 m3/min by considering an extra rate of 130% for agricultural drainage tunnels [9].

10.2.3 Dimensions and structures of the drainage tunnel
The drainage tunnel was designed according to the following conditions:•

Only one drainage tunnel is installed in the center of the underground facility.

•

Drainage capabilities (an inclination and a cross section) are ensured to make groundwater inall pits flow by gravity in case of the long-term shut down of all power supply.

•

The inner cross section is determined to be a “type-2r standard horseshoe-shaped cross section
with the finished radius r = 2.7 m” because a “simultaneous work method of excavation andlining” is applied with consideration of the construction period of the drainage tunnel.

•

For the risk of water damage, we have determined that “In case of power failure, it is acceptablefor water level not to reach the height of beams (1.1 m above the bottom slab) in the accelerator
tunnel.”

The length of the drainage tunnel was determined to be 4,027 m. A storage tank (L50 m x W10 m x H2 m
= 1,000 m3) was determined to be installed on the pithead yard of the drainage tunnel, and a culvert 258 m
in length was determined to be installed towards a river for discharging. The overall length is 4,335 m.
Figure 10.3 shows an overall structural drawing of the drainage tunnel.

– Tohoku ILC Civil Engineering Plan –

82

10

Drainage Facilities

Plan View

Longitudinal Profile “Cross Section A-A”

Legends:
CentralDrainage Pipe

Longitudinal Profile “Cross Section B-B”

VerticalDrainage Ditch
Drainage Pit
Drainage Tank
Water Pump

Figure 10.2. A schematic drawing of the sectional drainage system in the accelerator tunnel.

– Tohoku ILC Civil Engineering Plan –Plan View of the Detector Hall Side (Upstream Side) s=1:10000
Interface

Shotcrete

Drainage Tunnel

Lining Concrete

10.2 Design specifications

Standard Cross Section of the Drainage Tunnel(Cross Section of DII) s=1:100

Invert Concrete

Side View of the Storage Tank
CulvertStorage Tank

Structural Drawing of the Interface

s=1:300
Drainage Tunnel

s=1:100

Drainage Tunnel

Bottom Slab Concrete(σ28＝18N/mm2, t=300, the amount ofreinforcing bars 100kg/m3)

Connecting Pit(3 m in depth)

Figure 10.3. An overall structural drawing of the drainage tunnel.
83– Tohoku ILC Civil Engineering Plan –Overflow Dam(σ28＝18N/mm2, t=300, the amount ofreinforcing bars 100kg/m3)

84

10

Drainage Facilities

Support patterns of the drainage tunnel were determined to be as follows: pattern pithead-DII for sections
with an overburden of 2D (12.08 m) or less; pattern DI for those with an overburden of 2D to 30 m; pattern
CI for those 147 m in length near the accelerator tunnel; and pattern CII for other sections.
Support and lining structures were determined as Table 10.1 in accordance with standard support patterns
for agricultural drainage tunnels. Figures 10.4 to 10.7 show standard cross-sectional views and support
patterns of rock mass classes.

Table 10.1. Support and lining structures of the drainage tunnel
Rock
mass
classesCIOne
digging
length
1.5 m

CII

Shotcrete

Rock bolt

Steelsupport

Lining concrete

Invertconcrete

A thickness of A length of 2 m
5 cm
1.2-m intervals in the(18 N/mm2) circumferential direction
1.5-m intervals in thelongitudinal direction
A yield strength of 117.7 kN–

A thickness of
20 cm(18 N/mm2)

A thickness of
20 cm(18 N/mm2)

1.2 m

A thickness of A length of 2 m
5 cm
1.2-m intervals in the(18 N/mm2) circumferential direction
1.2-m intervals in thelongitudinal direction
A yield strength of 117.7 kN–

A thickness of
20 cm(18 N/mm2)

A thickness of
25 cm(18 N/mm2)

DI

1.0 m

A thickness of A length of 2 m
10 cm
1.0-m intervals in the(18 N/mm2) circumferential direction
1.0-m intervals in the
The entire
longitudinal direction
circumference A yield strength of 117.7 kNof a wire net

H-100×100
×6×8
@1.0m

A thickness of
20 cm(18 N/mm2)

A thickness of
25 cm(18 N/mm2)

DII

1.0 m

A thickness of (Excluding 120° of the crown)
12 cm
A length of 3 m(18 N/mm2) 1.0-m intervals in thecircumferential direction
The entire
1.0-m intervals in thecircumference longitudinal directionof a wire net A yield strength of 117.7 kN

H-100×100
×6×8
@1.0m

A thickness of
20 cm(21 N/mm2)

A thickness of
25 cm(21 N/mm2)(120° of the crown)“Filling-type FP” A length of 2m
0.5-m intervals in thecircumferential direction
1.0-m intervals in thelongitudinal direction
A yield strength of 117.7 kN– Tohoku ILC Civil Engineering Plan –Shotcrete
Shotcrete

Lining Concrete
Lining Concrete

10.2 Design specifications

Cross Sectional View s=1:50

Rock bolts

Invert Concrete

Invert Concrete

Detailed Cross Sectional View s=1:20
Cross Section A-A
Treatment for Head

Lining Concrete

Figure 10.4. Standard cross-sectional view (left) and support pattern (right) of class CI.

85– Tohoku ILC Civil Engineering Plan –Shotcrete

Rock bolts

Protection Mat(300x300x10)
Nut (M24)
Bolt
Washer (SS400, 150x150x9)

86– Tohoku ILC Civil Engineering Plan –Cross Sectional View s=1:50
Shotcrete

Shotcrete

Lining Concrete
Lining ConcreteRock bolts

Invert Concrete

Invert Concrete

Detailed Cross Sectional View s=1:20
Cross Section A-A
Treatment for Head
Shotcrete

Rock bolts

Protection Mat(300x300x10)
Nut (M24)
Bolt
Washer (SS400, 150x150x9)

Lining Concrete

10
Drainage Facilities

Figure 10.5. Standard cross-sectional view (left) and support pattern (right) of class CII.

Shotcrete

Lining Concrete

Shotcrete

Lining Concrete

10.2 Design specifications

Cross Sectional View s=1:50

Wire NetRock bolts

Invert Concrete

Invert Concrete

Detailed Cross Sectional View s=1:20
Cross Section A-A
Steel Arch Support

Rock bolts

Lining Concrete
Treatment for Head
Protection Mat (300x300x10)
Nut (M24)
Bolt
Washer (SS400, 150x150x9)

Figure 10.6. Standard cross-sectional view (left) and support pattern (right) of class DI.

87– Tohoku ILC Civil Engineering Plan –Wire Net

Shotcrete

88– Tohoku ILC Civil Engineering Plan –Cross Sectional View s=1:50
Shotcrete

Filling-type Fore Polling

Shotcrete

Lining Concrete

Lining Concrete

Wire NetRock bolts

Invert Concrete
Invert Concrete

Detailed Cross Sectional View s=1:20
Cross Section A-A

Steel Arch Support

Cross Section B-B
Steel Arch Support

Rock bolts

Filling-type Fore
Polling

Shotcrete
Wire Net

Shotcrete

Lining Concrete
Lining Concrete

Figure 10.7. Standard cross-sectional view (left) and support pattern (right) of class DII.

Drainage Facilities

Protection Mat (300x300x10)
Nut (M24)
Bolt
Washer (SS400, 150x150x9)10Treatment for Head

10.3 Construction plan89

10.3 Construction plan
10.3.1 Outline of the construction
Construction methods were according to the following conditions:•

A blasting excavation method, a full-face technique, is applied.

•

Concepts of pay lines (for outbreak, extra shot, and extra lining) are in accordance with theestimation standards.

•

Standards on excavating equipment (drill carriages, muck loaders, muck cars, concrete guns,
agitator cars, battery-driven locomotives, and other vehicles) are in accordance with theestimation standards.

•

For the mucking method, a (double-tracked) rail method is applied because the designed
excavation cross section of the drainage tunnel is as small as 20 to 35 m2.

•

The excavation muck is assumed to be placed near a pithead temporarily, and then transported
secondarily to a place 10 km away from the pithead by 10-ton dump trucks for disposal. Since
the appearance of mineralized muck is assumed to be less likely according to the results ofgeological surveys, we do not consider the costs and facilities for mineralized muck disposal. If
mineralized muck appears during construction, it is disposed of appropriately.

•

Types and standards of in-pit and pithead yard temporary facilities are in accordance with theestimation standards; however, a surplus of over 1,000 m is included appropriately according
to length.

10.3.2 Outline of the construction process plan
Figure 10.8 shows the overall processes for the drainage tunnel. The construction period was estimated at
88.5 months.
In addition, the present construction process plan does not include the following activities: the new
installation of roads from ordinary roads to pithead yards for construction; the widening and reinforcementof existing roads; and the rebuilding and new installation of bridges. This is because these are assumed tobe conducted in advance with other construction work as necessary. Similarly, the present construction
process plan does not include the periods necessary for obtaining land for pithead yards, roads forconstruction, surplus soil disposal facilities, and other purposes.

– Tohoku ILC Civil Engineering Plan –90– Tohoku ILC Civil Engineering Plan –

Year
Month
Preparation
Section DII
Section DI
Excavation Section CII

Section DI
Section CII
Section CI
Waterproof lining/reinforcing
bars

Invert/reinforcing bars

Storage tank
CulvertClean-up

Figure 10.8. Processes for the drainage tunnel.

10Drainage Facilities

91

11 Outline of the Construction Plan

Figure 11.1 shows a table of the outlined overall processes. Construction period was estimated at 90.8
months.
The construction period is determined by an excavation section starting from AS-10 towards a loop section
at an end. In this excavation section, the construction of a main linear accelerator tunnel starts most lately
due to the longest length of access tunnel AT-10. Since the end has no access tunnels, in addition, one-way
tunneling is to be conducted in the section starting from access hall AH-10 towards the loop section; thus,
methods for shortening the construction period are limited.
Though the drainage tunnel has as long a length as 4.3 km and also has a long construction period, it is tobe completed before the beginning of facility usage.

– Tohoku ILC Civil Engineering Plan –92– Tohoku ILC Civil Engineering Plan –

Year
Month
Access tunnel

Beginning of DR facility
construction
Beginning of facility construction for AH-10 toa loop section

Damping ring
Accelerator tunnel

AH-10 to a loop section

Detector hall

Excavation of the arch

AH+10 to a loop section
In-shaft facility construction can start
Beginning of facility
construction in the DH

Excavation of the body

Building concrete
Detector hall shaft

Main shaft
Utility shaft

Beginning of facility construction in theaccelerator tunnel

Drainage tunnel Drainage tunnel
Surface work

11

Figure 11.1. Table of the outlined overall processes.

Outline of the Construction Plan

93

12 Approximate Construction Costs

Table 12.1 shows the approximate construction costs. These construction costs were estimated on the basisof equipment ownership costs, material unit costs, and labor unit costs disclosed in the 2014 fiscal year.
This estimation was conducted for the civil engineering plan settled by the Tohoku ILC Preparation Officewith consideration of the conditions (topography, geology, and other features) intrinsic to the Kitakami site
by creating a construction plan in accordance with the Civil Engineering Estimation Standards (the 2014
fiscal year edition) of the Ministry of Land, Infrastructure, Transport, and Tourism.
We consider that the construction plan does not require any major changes from the 2014 fiscal year
onward; since unit costs vary every fiscal year, however, the results of estimates are also expected to vary.

Table 12.1. Approximate construction costs (unit: 100 million yen)An overall length of 20.5 km
PartConstruction
priceSpecifications

AT: 5 tunnels （5,662 m in length)
Access tunnels AH: 5 halls (248,354 m3)
Preparation of AS yards: 5 places x 18,193 m2
Semicylindrical shape (20.5 km in length)
Accelerator Partition walls: Made on the site (15.3 km in length)
tunnelDR, end loop sections, BDS (beam and service), andother components
Large cavern, shafts, and peripheral tunnels
Detector hall Same pithead of AT-DH/AT-DR
Preparation of yards: 78,500 m2
A tunnel, a storage tank, and a culvert (4,335 m in
Drainageoverall length)
facilities
In-pit cross water drainage and out-pit facilities
Total

247

644

134
73
30
1,127

– Tohoku ILC Civil Engineering Plan –95

13 Challenges for the Future

The Global Design Effort is conducting detailed examinations for the periphery of the positron source,
beam dump, detector hall, and other components. We will continue coordination in response to the progressof these examinations in the future.
We consider that other detailed geological surveys and design examinations are required for a detailed
design, mainly in the following places:•

Cross points of rivers•

Pitheads•

Cross areas of the crown of the detector hall and the shafts

The result of the geological surveys shows that the cross points of rivers have worse geological conditions
in comparison with other places. Since these points are limited, however, we have not conducted detailed
examinations for them so far. Construction methods are required to be examined in detail for places with athin overburden and rivers directly above them. Further examination of influences on the rivers is also
required.
Pitheads on the ground surface generally have poor geological conditions and conditions are expected to
be varying. We consider that the pitheads require detailed geological surveys by the time design for
implementation is conducted.
We consider that the detector hall and shafts have good stability because of good rock mass conditions. On
the other hand, we consider that the cross areas of the crown (the roof part) of the detector hall and shafts
require other detailed examinations for their strength and stability.

– Tohoku ILC Civil Engineering Plan –References

97

References[1] C. Adolphsen et al., ILC Collaboration, “The International Linear Collider Technical Design Report Volume 3.II: Accelerator Baseline Design”, arXiv:1306.6328 [physics.acc- ph].
[2] L. Evans and S. Michizono, Linear Collider Collaboration, “The International Linear Collider
Machine Staging Report”, arXiv:1711.00568 [physics.acc-ph].
[3] Added to the GSI Maps (by the Geospatial Information Authority of Japan).
[4] Added to the Seamless Digital Map of Japan (1:200,000) (by the Geological Survery of Japan, theNational Institute of Advanced Industrial Science and Technology).
[5] Hikoharu TAKAHASHI. “Applied Geological Examination for Tunnel Spring Water.” Railway TechnicalResearch Report. 1962, No. 279, pp. 1-103.

[6] Hiroshi OSHIMA and Shinichi NISHIMORI. “Research on Hydrologic Survey Methods for Tunnel
Construction.”

Railway Technical Research Report. 1979, No. 1108, pp. 1-186.

[7] Kenichi FUMIMURA and Michito SHIMO. "Development of GIS System for Predicting Tunnel
Inflow and Dewartered Area.” Papers/Reports of Tunnel Engineering Research Presentations. 2003,
13, pp. 327-332.
[8] Design and Construction of Underdrainage. The Agricultural Upland Development Association (ageneral incorporated association). Mar., 1982, pp. 62.
[9] Standards and Technical Instructions for “Aqueduct Tunnels” in Land Improvement Activity Plan
Design and Standard Design. The Structural Improvement Bureau, the Ministry of Agriculture,
Forestry, and Fisheries. Oct., 1996.

– Tohoku ILC Civil Engineering Plan –99Part IV

Appendix
Part IV Appendix– Tohoku ILC Civil Engineering Plan –

101

A

Other Facility Location Plans

Since the Kitakami site has relatively gentle topography, multiple facility location plans for the site can becreated easily. The underground facility changes little even though the facility location changes; however,the lengths of the access tunnels change depending on topographical conditions. Table A.1 now lists thelengths of the access tunnels for another two plans in which the location of the detector hall is different.
Plan A of detector hall location is detailed in this document. Plan B is that the detector hall is moved 180
m to the west. Plan C is a facility location plan in which the detector hall is placed to the north of Okita
River, as introduced in Chapter 6. The comparison of these three plans shows that the variation of the total
length of the access tunnels is within approximately 20%.
These location plans have different features. We can examine them in terms of various aspects including
the total length of the access tunnels after the details of the ILC accelerator facility are finally decided.

Table A.1. List of the lengths of the access tunnels
Entry point(pithead)

Location of the detector hallPlan A
Plan B
Plan C

AS−10
AS− 8
AS−DH
AS−DR
AS+ 8
AS+10
Total length

1,707 m
817 m
747 m
817 m
427 m
1,147 m5,662 m

1,503 m
691 m
693 m
763 m
283 m
943 m
4,876 m

1,990 m
1,560 m
1,075 m
560 m
935 m
715 m
6,835 m– Tohoku ILC Civil Engineering Plan –

103

B

Present Examination of the Main Beam Dump Cavern (for Reference)

We are examining a cavern containing the main beam dump. Drawings for the examination are shown fromthe next page onward.

– Tohoku ILC Civil Engineering Plan –104– Tohoku ILC Civil Engineering Plan –B

Present Examination of the Main Beam Dump Cavern (for Reference)

Figure B.1. Plan view of the periphery of the main beam dump cavern.

105

Figure B.2. Cross section A-A of the main beam dump cavern.

Figure B.3. Cross section B-B of the main beam dump cavern.

– Tohoku ILC Civil Engineering Plan –

106

B

Present Examination of the Main Beam Dump Cavern (for Reference)

Figure B.4. Cross section C-C of the main beam dump cavern.

Figure B.5. Cross section C’-C’ of the main beam dump cavern.

Figure B.6. Cross section D-D of the main beam dump cavern.

– Tohoku ILC Civil Engineering Plan –107

C Examination Drawings (for Reference)

We are organizing drawings for examination with the High Energy Accelerator Research Organization as
the central figure. Drawings as of January 2020 are shown from the next page onward. Though the Tohoku
ILC Civil Engineering Plan was examined according to drawings as of 2018, no major changes have been
conducted up to now.

– Tohoku ILC Civil Engineering Plan –108

Cross Section D-D (1:200)

Position of awaterproof sheet

See A-A

Cross Section E-E (1:200)

Cross Section A-A (1:75)

Detailed Drawing of Part B (1:1000)(Common for all 5 places)

Cross Section F-F (1:200)
Cross Section H-H (1:200)

Cross Section G-G (1:200)

Notes

Correction

Revised by Date
Made byName
TanakaDate
12/17/2019

General view of the ILC

Checked byApproved by

Cross Section C-C (1:200)

Scale

m
Projection method

UnitHigh Energy Accelerator
1/20000
Research Organization (KEK) A0

109Detailed Drawing of Part AA (1:1000)

See Cross Section S-S

See Cross Section S-S

Detailed Drawing of Part W-W (1:100)
Cross Section AB-AB (1:100)
Position of awaterproof sheet

See Cross Section S-S

Detailed Drawing of Part U (1:500)

Cross Section S-S (1:100)

Detailed Drawing of Part V (1:500)

Cross Section X-X (1:100)
Cross Section AC-AC (1:100) Assembly Part
Joining from an RTML to the accelerator room
See Cross Section S-S

See Cross Section S-S

Cross Section T-T (1:100)
Cross Section AD-AD (1:100)

Cross Section Z-Z (1:200)

Notes

Correction

Position of awaterproof sheet

Revised by Date

Name
Made by

TanakaDate
12/17/2019

Electron side of the ILC tunnel

Checked byApproved by

Scale

Cross Section Y-Y (1:100)m
Projection method

UnitHigh Energy Accelerator
1/10000
Research Organization (KEK) A0

110

Detailed Drawing of Part AE (1:1000)

See Drawing AH-AH

See Drawing AH-AH

Cross Section AL- AL (1:100)

Cross Section AE-AE (1:100)

Assembly Part
Joining from an RTML tothe accelerator room

Detailed Drawing of Part AK (1:500)

See Drawing AH-AH

Detailed Drawing of Part AJ (1:500)
Cross Section AH-AH (1:100)

See Drawing AH-AH

Cross Section AM-AM (1:100)

Cross Section AF-AF (1:100)

See Drawing AH-AH

Cross Section AI-AI (1:100)

Cross Section AO-AO (1:200)
Cross Section AG-AG (1:100)

Notes

Position of awaterproof sheet

Correction

Revised by Date

Name
Made by

TanakaDate
12/17/2019

Positron side of the ILC tunnel

Checked byApproved by

Scale

Cross Section AN-AN (1:100)m
Projection method

UnitHigh Energy Accelerator
1/10000
Research Organization (KEK) A0

111

For Cross Sections N, O, P, Q, and AQ, see other drawings and the crosssection of the detector hall.

Detailed Drawing of Part B (1:1000)

Cross Section AP-AP (1:100)

Cross Section I-I (1:100)

Cross Section J-J (1:100)

Notes

Correction

Revised by Date
Made byCross Section K-K (1:100)

Cross Section L-L (1:100)

Name
TanakaDate
12/17/2019

Damping ring of the ILC

Checked by

Cross Section M-M (1:100)

Approved by

Cross Section R-R (1:400)

Scale

m
Projection method

UnitHigh Energy Accelerator
1/50000
Research Organization (KEK) A0

112

See Cross Section O-O
See Cross Section O-O

Detailed Drawing of Part B (1:1000)
Cross Section N-N (1:300)

Cross Section O-O (1:400)

See Cross Section O-O
See Cross Section O-O
See Cross Section O-O
See Cross Section O-O

See Cross Section O-O

Cross Section AQ-AQ (1:300)

Notes

Cross Section P-P (1:300)

Correction

Revised by Date

Name
Made by

TanakaDate

Cross sections of the detector hall of the ILC

12/17/2019

Checked byApproved by

Cross Section Q-Q (1:400)m
Projection method

UnitHigh Energy Accelerator
Research Organization (KEK)

Scale
1/5000A0