Volume 5, Issue 3 September 2020

Reports

Recent technological development at Japan Construction
Method and Machinery Research Institute
Hiroyuki Takenouchi
Engineering Adviser
Japan Construction Method and Machinery Research Institute

Outline of Japan Construction Method and Machinery Research InstituteHistory and research philosophy
Japan Construction Method and Machinery ResearchInstitute (JCMMRI) was established in October 1964 as anaffiliated organization of Japan Construction Machinery andConstruction Association (Photo 1). The purpose of its
establishment is to contribute to our nation’s economic
development by promoting technology improvement andrationalization of construction projects through research andtesting in the area related to construction machinery andmechanized construction works.
Ever since the establishment, commissioned by relatedorganizations such as the national government and privatecompanies, we have been conducting various tests, surveys
and researches on construction method and machinery inwide diversity of works and projects such as roads, bridges,tunnels, and dams, including notable major projects in Japanfor more than half a century. We have also focused on
construction safety and environmental issues such as noise,vibration, and exhaust gas countermeasures.

Photo 1. JCMMRI at the foot of Mt. Fuji

We are determined to play the leading role as Japan's only comprehensive testing and research institute for construction
machinery and mechanized construction, while maintaining the tradition of "think with our own head, investigate with
our own feet, and test with our own hands" from the beginning.

Activities
The work carried out by JCMMRI covers a wide range of fields, such as
research and study, performance test and evaluation, technology
development, and technical support. In addition to on-site survey andexperiments using test facilities, we also perform all kinds of work related toconstruction technology which requires advices and judgment as the thirdparty, such as surveying and analysis on construction productivity data andequipment ownership cost for construction cost calculation.
Researches and studies have been conducted on various issues related toconstruction methods, maintenance of structures, and construction
machinery throughout construction work. As the recent tendency, thenumber of researches related to maintenance, repair and reinforcement isincreasing, as the importance of maintenance has been strongly called outagain. As for bridges, for examples, we are taking measures to prevent fatigue
damage to steel decks, fatigue durability of bridge expansion joints and PC
decks used for floor deck replacement work (Photo 2). As for tunnels, field
verification of Robot technology for the purpose of inspection developed byprivate companies was carried out (Photo 3).
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Photo 2. 4MN fatigue testing machinefacilityVolume 5, Issue 3 September 2020
For construction machinery, we have been conducting research on performance improvement and development of newmodels in the fields of disaster prevention and restoration
measures, environmental measures and safety measures.
Performance tests, evaluations and ratings are also conducted.
Automatic control and remote operation have become recent
important issues for snow removal work (Photo 4) and earlyrecovery work from natural disasters to reduce social impact.
With regard to information and communication technologyoriented construction, so called ICT-construction, which has beenstrongly promoted by the Ministry of Land, Infrastructure,
Transport and Tourism, we have been providing support for thevision and strategy, and spreading the actual practice inconstruction field (Photo 5). We also have been engaged in theestablishment of technical standards for ICT-construction bymaking use of our accumulated knowledge on elemental
technologies such as machine control and machine guidance and3D measurement technology.
Photo 3. Verification test in the simulated tunnel

Photo 4. Automatic control of snow removal work

Photo 5. Hands-on workshop for ICT-construction

Technology development such as new models, new methods and new materials has been conducted through joint
research projects with construction companies and private companies handling construction machinery and materials, inaddition to contracting from the ordering party. In this report, two cases of recent technical development through joint
research with private companies and universities are introduced.

Case (1) Development of Multi-divided Precast Lining System for Mountain Tunnel
Background and purpose
It is assumed that securing labor will become more difficult due to the shortage of manpower in the construction industry
from now on, and improving productivity to reduce the number of workers in construction is one of the urgent tasks tobe tackled today. In the construction of mountain tunnels, there often occurs cases where rapid construction of the entire
tunnel work is required to shorten the construction period or to recover the process delay. For such cases, in general,application of precast lining can be considered as a rapid lining work. But, in the current precast lining work, the size ofprecast members is significantly large because the lining is commonly divided into two sections. This leads to the difficultyof transportation, loading, and erection of precast members during excavation work going on at the same time. And so,the applicability in a narrow tunnel space becomes an issue. With these backgrounds, aiming at significant improvementof the productivity of the lining concrete construction, the joint research team has been developing Multi-divided Precast
Lining System that enables more than double the speed of conventional construction.

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Volume 5, Issue 3 September 2020
Outline of Multi-divided Precast Lining System
Multi-divided Precast Lining System was developed for highway tunnels with two lanes where the general cross section
is about 80 m2. The basic structure of multi-divided precast lining consists of 6 pieces for 1 ring with the width of 1.0 m.
The arc length of one piece is reduced to about 2.8 m, one-third of the conventional one, so that workability oftransportation, loading and erection can be greatly improved. For the purpose of quick assembly, the wedge joint
between pieces and the pin insertion joint between rings are adopted, which are common in shield tunnel construction(Fig. 1).
PLA
Multi-divided precastNlining
Backfill(Air mortar)

GroutholeSide wallCROSS
SECTION

Piece joints

Ring joints
Fig. 1. The basic structure of multi-divided precast lining

The connecting part of the leg of the side wall concrete is designed as a pin structure, and the wedge joint between thepieces is designed as a rotating spring structure. As for the ring arrangement in the tunnel axial direction, the straightjoints arrangement was adopted after the study on both of staggered arrangement and straight joints arrangement.
Regarding the structural stability, following three states were examined; the self-supporting state after the ring waserected, the biased pressure loading state during backfilling performed from the grout holes of each piece, and theloading state of the ground load after backfilling.
The erection machine for the multi-divided precast lining
system is a gantry type, unlike conventional heavymachines, that allows other vehicles to pass through thelower space. Therefore, excavation work and lining work
can be done in parallel. This erection machine is composedof an erector-equipped assembly device and a shaperetention device for retaining the ring shape after
assembly (Photo 6). It travels on rails installed on thetunnel roadbed in the same manner as the travelling arch
center. Multi-divided precast linings are erected by theassembly device in order from one side, and the shape ofthe erected linings are maintained by the shape retention
device immediately after erection.

Photo 6. Erection machine for multi-divided precast lining
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Volume 5, Issue 3 September 2020
Full-scale verification experiment
2 rings of full-scale precast lining were assembled on the steel
pedestal to check the assemble performance. And, assembled
precast lining was jacked down to stand by itself to confirm thestability in the state (Photo 7). No significant deformation wasobserved in the self-supporting state.
In addition, the bending test of the joint specimens of 2 pieces wascarried out, and it was confirmed that the breaking load was higher
than the design bending proof load specified by the material.

Future outlook
Currently, in parallel with the experiment, we are comparing theperformance of the multi-divided precast lining and theconventional lining by non-linear analysis. Demonstration tests are
now being carried out in the full-scale simulated tunnel to confirm
the workability (Photo 8). After the experiment, we plan to apply
this system to new tunnel constructions and renewal projects that
require rapid construction of lining concrete.

Photo 7. 2-ring assembled precast lining

This research and development have been carried out by the joint research with Shimizu Corporation and IHI Kenzai
Kogyo Co., Ltd.

Photo 8. Demonstration test in the simulated tunnel at JCMMRI

Case (2) Development of On-Site Shot PrinterBackground and overview
In the field of concrete, as one of the three pillars of i-Construction undertaken by the Ministry of Land, Infrastructure,
Transport and Tourism, precast construction with factory products is being promoted. But there still exists more room
left for research and development in this field, compared to productivity improvement in other fields. The joint researchgroup has reached to the idea that the technology improvement required by the present society for the concrete field is
not only the shift from on-site casting to application of precast factory products, but the development of a concrete
structure manufacturing technology based on a completely new concept. Based on this idea, the group has beenpromoting research and development focusing on the resent 3D printing technology. In this research, we proposed atechnology to build concrete structures by direct print modeling on-site, namely On-Site Shot Printer system. Thistechnology is a combination of 3D printing technology and ICT construction technology, which have been active in recentyears. In order to realize this system, the spraying technology of cement-based material, which is indispensable to thissystem, was deeply studied and succeeded to develop a new hybrid spraying system that has the advantages of
conventional technologies of both "dry mix shotcrete" and "wet mix shotcrete".

Hybrid Spray System14

Volume 5, Issue 3 September 2020

Direct print molding on-site requires long-distancetransport of material for molding. At the same time,
it is important to secure the strength of the shaped
article as a structure. The "dry mix shotcrete", inwhich the materials are individually conveyed andmixed and sprayed at the nozzle, is advantageous forlong-distance transport. On the other hand, the "wetmix shotcrete", in which premixed materials are
directory sprayed from the nozzle, is effective toobtain secure strength. Since both performances arenecessary for the On-Site Shot Printer, we havedeveloped the new Hybrid Spraying System that hasthe advantages of both technologies (Fig. 2).
In order to confirm the performance of the Hybrid
Spray System, we conducted a spraying experiment
aiming at the material transport distance of 160 m(the maximum performance of the system is 300 m)
under the conditions that discharge volume is 18 kg /min and mortar flow is 170 mm. As the result of thisexperiment, it was confirmed that the mortar wasstably supplied and sprayed with expected quality by
the Hybrid Spray System.

Fig. 2. Hybrid Spray System

Direct print molding on-site by utilizing ICT construction machinery
In order to build concrete structures by direct spraying on-site, the position and the movement of the spray nozzle must
be properly and precisely controlled automatically. For this control, ICT construction equipment was decided to be utilized
because they can be controlled by the computer program and is resistant to sever site conditions such as rain, wind anddust. The spray nozzle is attached to the bucket of the ICT aided hydraulic excavator. The position and the movement of
the spray nozzle are controlled by the design data created and input to the ICT aided hydraulic excavator. By utilizing theseICT construction machine technologies, we succeeded in direct printing and molding concrete structures assuming walls
and buried formwork at present.

Photo 10. Direct print molding of buried formworks

Photo 9. Direct print molding of a wall

fframesworksuriedburiedrameworkstructure
Demonstration experiment was conducted at the field of JCMMRI. In this demonstration experiment, it was confirmedthat a wall with about 1 m height and about 1.8 m width can be formed in about 60 minutes (Photo 9). Photo 10 showsa molding situation assuming buried formworks to be placed on the outer surface of a rectangular pillar with 1 m width
× 1 m depth ×2 m height. It was molded up to a height of 1.5 m on each surface in about 25 minutes. These specimens
were successfully constructed by direct print molding without any material crushing or peeling off.

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Volume 5, Issue 3 September 2020
Target utilization scene
At the present stage, the feasibility of using it as a buried formwork has beenmostly verified, and the following uses are envisioned as directions for future
research and development.
Phase1: Current stage
Buried formworks, especially for construction with difficulty inmaterial transportation
Phase 2: Accurate and safe control stage (Fig. 3)
Large structural members of substructure such as abutment, pier,caisson, etc.
Phase3: Delicate control stage (Fig. 4)
Structural members of bridge superstructures such as floor slabs,guard walls, etc.
This research and development have been carried out by the research anddevelopment group consisting of Gifu University, JCMMRI, Sumitomo Osaka
Cement, Shimizu Construction, NIPPO, Maruei Concrete Industry and FTS. It is
supported by the Construction Technology R & D Grant System of 2019 (theMinistry of Land, Infrastructure, Transport and Tourism).

Fig. 3. Image of Phase 2Fig. 4. Image of Phase 3◆ A brief CV of Mr. Hiroyuki Takenouchi
Hiroyuki Takenouchi is the engineering adviser of Japan Construction Method and Machinery
Research Institute. He joined the institute upon graduating from the Department of Civil
Engineering of Tokyo Institute of Technology in 1974. Since then he has engaged in a number ofresearch and development works on wide variety of construction method and machinery. He
specializes in strength and durability technology of structures such as bridges. He is also thePresident of MK Engineering Inc., engaged in consulting business to protect infrastructure withknowledge, practice, and industry-government-academia networks.

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