10th Asian Regional Conference of IAEG (2015)

Case study of a tunnel with time-dependent behavior in a volcanic area of Hokkaido
Yoshihiko ITO(1), Kenji OKAZAKI(2), Toshiyuki KURAHASHI(2), Hiroumi NIWA(3),Hideyuki MURAYAMA(3) and Terukatsu SASAYA(3)(1) Public Works Research Institute, Civil Engineering Research Institute for Cold Region, Japan
E-mail: yos-ito@ceri.go.jp(2) Public Works Research Institute, Civil Engineering Research Institute for Cold Region, Japan,(3) Fujita Corporation, Japan
Abstract
Records of the construction and repair of a tunnel with time-dependent deformation
were analyzed to develop judging method of time-dependent deformation. As a result,release of in situ stress of rock converged until about 80 days and time-dependent
deformation was inferred to result from rock degradation by the change of rocksurroundings mainly with groundwater inflow. The score of tunnel face estimation was
found to be difficult to separate with and without time-dependent deformation part clearly.
Although the displacement value at the part of time-dependent deformation of the tunnel
had a tendency to be larger than those at the part without deformation, the boundary value
was too small (about 4mm of crown settlement) to be adopted as threshold to determine
tunnel support patterns. By the re-examination of geological description of advanced
drilling at the time of construction, it was verified that the geological description should be
more respected to predict time-dependent deformation parts.
Keywords: time-dependent deformation of tunnel, advanced drilling, displacement, geologicaldescription

1.

Introduction

tunnel with time-dependent deformations to clarify
the mechanism of time-dependent behavior and tofind the prediction method of time-dependent
behavior of the tunnel.

Tunnel deformation due to time-dependent
behavior of ground is one of the most important
problems for tunnel constructors. There are manycases of time-dependent deformation of tunnels inJapan (Table 1, JSCE (2003)). Though mostconstructors estimate and deal with rapid degradationof rock by monitoring, they sometimes underestimate
gradual ones because of the luck of geologicalcomprehension and result in time-dependent
deformation of tunnels. Though some studies havereported on such degradation of rocks due toweathering and mineral leaching (Oyama et al., 1998;
Kato et al., 2011), precise and in-situ estimation
method for time-dependent deformation of tunnels
has not been established sufficiently.
We are undertaking a project study focused ontime-dependent behaviors of rock mass from theperspective of geology, mineralogy and geophysics
and reported some important results (Murayama et. al(2015), Niwa et. al (2015a, 2015b), Okazaki et. al(2015a, 2015b)). In this study, detailed analyses werecarried out for construction and research results on a2.

Outline

The studied tunnel is 2.1-km in length, and wasconstructed using NATM and was opened in 2003.
Figure 1 shows the geological section, geology,
actual tunnel support pattern, displacement(convergence of upper half of the tunnel and crownsettlement), convergent time, and the three repaired
areas (A, B, C) of the tunnel. Geology of the tunnel
was Miocene andesite (An), volcanic breccia (Vb),and tuff breccia (Tb).
Andesite was relatively hard and had cracks atseveral places. It had undergone minor hydrothermal
alteration. Auto-brecciated part of andesite wasrelatively soft and had many cracks. Volcanic breccia
was soft and had undergone minor hydrothermal
alteration. Tuff breccia was distributed in the form ofblocks, which were soft, friable, and partiallyfragmented. During construction, displacement of the1

10th Asian Regional Conference of IAEG (2015)

Table 1 Time-dependent deformation of tunnels in Japan (Compiled from Japan Society of Civil Engineers,
2003)
Geology

0.5

Brecciated tuff, andesite

20

Weathered granodiorite

15

Tuff breccia, altered andesite

Prefecture

Place

Rebunge

Hokkaido

Road

SenganAkita/Iwate

Road

Mikuni

Hokkaido

Road

Asamayama

Gunma

Road

EnasanNagano/Gifu

Road

Ureshino

Saga
Nagasaki
/Saga

Road

Timberingsupport Method
NATM

Road

NATM

Kamui

Hokkaido

Railway

Rebun-hama

Hokkaido

Railway

Usuitouge

NaganoRailway

NATM

9Tsukayama

Niigata

Railway

Timberingsupport Method

4 months, 20
years

Tawarazaka

MethodYears until
deformation
revealed

Name

Timberingsupport Method
Timberingsupport Method
Timberingsupport Method
NATM

0Tuff breccia, Tuff, andesite,
Mudstone
Granite with argillicalteration
Tuff breccia, Shale

1

Andesite, tuff breccia

18

Serpentinite, black schist

1
14

Timberingsupport Method
Timberingsupport Method

E.L. (m)300-

Andesitic tuff, Alteredandesite
Andesitic lava, Volcanic
breccia6

Neogene mudstone

2,106(m)25020015010050-

An

Tb

Vb

An

Estimated 0An

CII

Displacement (mm)

20

Tb

An

Vb

Vb

CI

An Vb An

CI

Tb

Vb

CII

Tb

Tb

An

CII

CI

DII

An

Tb

DI

CI

DII

DI

Tb

DII
200

Convergence of
upper half (mm)Crown settlement (mm)Convergent time (day)0150(A)a (B)

-20

42m

80m

(C)

100

167m

-40
-60
62,000An50
062,50063,00063,500tunnel point (m) 64,000

Fig. 1 Geology, displacement and three repaired area (A, B, C) of the studied tunnel

2

Convergent time (day )geology by Tb An Vb Tb Tb Tb
坑口
An An
advanced
CII
drilling
TunnelsupportCII DII CII DIDII
pattern10th Asian Regional Conference of IAEG (2015)

140

Road surface upheaval （mm）

120
100
80
60

51 days after tunnel
opening
360 days after the
first repair
Crown settlement atconstruction stage

40
20
0
-20
63,55063,57063,59063,61063,63063,65063,67063,69063,710Tunnel point
Estimated geology at
Tuff breccia
excavating stage

Andesite

Tuff breccia

Class of ground

CII

Construction

No invert

The first repair
The second repair

Autobrecciated lava
DII

CI

CII

Inverted

No invert

Inverted

-

-

-

-

Inverted-

Fig. 2 Details of the area (C)areas (A, B, C) was not particularly large (20mm atmost).
At the tunnel, invert was settled for DⅠ and DⅡof the tunnel support pattern, and not settled for CⅠ
and CⅡ of it. From the geological observation ofadvanced drilling samples and cutting face, thegeology of three areas was estimated too good toinvert except some narrow part of the area (C). Also,
convergent time of three areas was not so large
compared with other areas without invert. There
seemed no reason to settle invert there from theresults of ordinary research.
Figure 2 shows the details of the area (C). The
tunnel was opened in January, 2003. Just before theopening, upheaval and cracking was observed
between tunnel point 63,565 and 63,663 of the area
(C). 51 days after the opening, the maximum
upheaval of road surface reached 120mm. The tunnel
was closed and was repaired immediately. Near the
repaired section, though small deformation was also
observed between about 63,680 and 63,732 in March,
2003, the area was not repaired at that time.
360 days after the first repair, the maximum
upheaval of this part reached 110mm, and the second
repair was carried out. Repair work was also
conducted at another two areas (A and B) where
heaving lasted for a long period of time andmaintenance of the tunnel structure was expected tobe difficult.
The value of crown settlement was less than
20mm, and convergent time was less than about 80

days. Influence of stress release for rock ofdeformation part by tunnel excavation was thought tobe convergent about 80 days at most. Comparing thevalue of road surface upheaval of 51 days after tunnel
opening with crown settlement during construction,
upheaval was remarkable at tuff breccia area between
about 63,630 and 63,670 of tunnel point. Comparing
value of road surface upheaval of 360 days after the
first repair with crown settlement at construction
stage, upheaval was remarkable at auto-brecciatedlava area between about 63,680 and 63,700 of tunnel
point.
In the tunnel, inverted section did not suffer fromtime-dependent deformation, while three timedependent deformation sections were not inverted.
Over-invert might be one of the methods to tunnels
with similar geological condition. But it would resultin overdesign and adequate threshold is needed.
3.

Methods

During construction of the tunnel, geology, tunnel
support pattern, crown settlement, convergence etc.,
were recorded at 99 sections of tunnel faces. Tunnel
faces were estimated by a check sheet. Table 2 shows
the check points and their scores from these sheets.
Each check point was scored from 1 to 5, and thesewere then summed to the total score to estimate
tunnel face. A high total score means bad conditionsof the tunnel face, while low score indicates goodconditions.

3

10th Asian Regional Conference of IAEG (2015)

Table 2 Check points and scores of face observations
Score
Face
condition

1
Stable2
Small rocks fall
off the face

3
Squeezing occurs
at the face

Condition ofunsupported
excavation
faceStanding (nosupportneeded)Loosening ofground and rockfalls occur fromtime to time
(ordinary support)

Compressiv
e strength

Withstands
hammerblows

100>σc≥20MPa
Crumbles when
hit by a hammer

Weathering/alterationNo
weathering;soundcondition

Discolouring
along rifts;
slightly reduced
in strength

Crack/fissur
e frequency

Spacingd≥1m

1m>d≥50cm

Barely able tostand and requires
early support after
excavation(immediate
support)20>σc≥5MPa
Crumbles when
hit lightly by ahammer
Generaldiscolouration,
considerably
reduced instrength50cm>d≥20cm

Crack/fissur
e conditions

Tight

Partially open

General Open

Slickensideobserved,unconsolidated
sand and gravel

Mode of
Cracking/fis
suringWater
inflow

Random,squaresd≥1m
None,
seepage
1little/min>V
None

Squares, massive

Layers,fragments, plates

Dripping
20>V 1little/min

Concentrated
100>V≥20little/min

Soil,fragmented,
unconsolidated
Entire faceV≥100little/min

Loosening

Softening

Deterioratio
n due towater

In this study, we correlated time-dependent
deformation of the tunnel with the score of faceestimation and measurement result of displacement.
We also re-examined the geological description ofdrilling samples at the time of tunnel construction
with respect to time-dependent behavior.
4.

4Unable tosupport itself,
the facecollapses
Support before
excavationneeded5
The face flowsout

5>σc≥1MPa
A hammer headends up lodged
in
Soil, clay,
fractured,
unconsolidated

1MPa>σc
Crushable witha fingertip

20cm>d≥5cm

5cm>dfractureunconsolidated
Interbeds ofthick (d≥5mm)clay, remarkableslickenside, soil,
sand and gravel
OthersCollapse,
outflow

OthersOthersOthersV≥1000little/min
Othersis a positive correlation between the two. From thefigure, most parts with the score of more than 20
were inverted, while most scoring less than 20 were
not. Whether invert settled or not was inferred tohave been mainly determined by the score.
In the non-inverted area, scores from the sections
with deformation (from about 20 to 12) overlapped
those from the section without deformation (fromabout 20 to 10). Therefore, it is difficult to estimate
whether the section would be deformed or not in the
future only by the total score of tunnel estimation.

Results and Discussion

4.1 Relation between crown settlement and total
scores of face estimation
Figure 3 shows correlation results of crownsettlement and total score of face estimation fortunnel sections with and without deformation. There

4.2 Relation between convergence and crownsettlement of non-inverted section
Figure 4 shows correlation results between

410th Asian Regional Conference of IAEG (2015)

convergence and crown settlement in the
non-inverted section. There is a positive correlation
between the two. Convergence value of thedeformation section seems to be larger than that of
the section without deformation. Therefore, we could
adopt about 4mm of crown settlement or 2.5mm ofconvergence as the threshold to determine tunnel
support patterns (whether invert was settled or not).
The threshold, however, is too small to be
adopted compared with that of other tunnels. The
estimation method might result in the overdesign oftunnel support pattern. However, there is a possibility
that the value could be used for screening to find thesection of time-dependent deformation of similargeological areas.
Fig. 3 Relation between crown settlement andscore of face estimation

4.3 Relation between convergent and score of faceestimation in non-inverted section
Figure 5 shows the correlation results between
convergent time (day) and total scores of faceestimation in non-inverted part. Convergent time oftime-dependent deformation section is less than about
80 days, while section without it is from about 20 to
200 days.
This means that sections of small convergent time
are not necessarily the section without
time-dependent deformation. The figure also suggeststhat rock degradation by release of in-situ stressmight end less than about 80 days at most, andtime-dependent deformation occurred by otherfactors. Rock degradation by mineral change in rockby the change of temperature, water and air is one of
the most important factors of time-dependent
deformation.

Fig. 4 Relation between convergence and crownsettlement of non-inverted part

4.4 Analysis of geological descriptions of drillingsamples between convergence and crownsettlement of non-inverted section
Geological features around the deformation partof tunnel was re-examined by checking the record ofadvanced drilling samples. We paid attention to thegeological descriptions of the record to find theprediction method of time-dependent deformation
part of the tunnel. That is descriptions such as“swelling” and “softening” (not “soft”). We also paid
attention to the groundwater descriptions in it.
Table 3 shows the examination results fromtunnel point 63,164 to 63,860. The zone wasestimated as C Ⅱ of the tunnel support pattern(without invert) except the area 4. The zone also
includes three deformation areas (A, B, and C) andno deformation areas (1 to 5).
There were many descriptions with regard totime-dependent behavior such as swelling orsoftening in the area C. Only taking thesedescriptions seriously, we could easily estimate that
there was a large potentiality of time-dependentFig. 5 Relation between convergent and score offace estimation in non-inverted part5

10th Asian Regional Conference of IAEG (2015)

Table 3 Examination results from tunnel point 63,164 to 63,860
Area(Area A,B,C
are repaired)
1
A(2nd Repair)

Tunnel Support
Pattern and
Tunnel Point
63,164CⅡ
63,206

Descriptions with
time-dependent
behaviour“Weakly swelling (2parts:4cm and 110cm insample length)”-

Othercharacteristic
descriptions

Groundwater inflow(TP means Tunnel
Point)(Litter/min)“Soft”

TP=63,164-13204: 15“Fractured,muddy”

TP=63,216:
Groundwater inflow
TP=63,204-63,239: 12“Weakly swelling (3parts:2.0m, 0.47m and1.7m in sample length)”“Soft and fragile”

TP=63,239-63,264: 85“Weakly slaking”“Soft and fragile”

CⅡ
63,2482

CⅡ
63,292B(2nd Repair)CⅡ
63,372

3

CⅡ“Softening”“Fragmental”

63,565C(1st Repair)4
C(2nd Repair)5

CⅡ
63,663
DⅡ(Inverted)
63,680CⅡ63,732
CⅡ
63,860Many descriptions (19parts) of “ weakly
Swelling” or “Swelling”“Rather soft andfragile”“Softening”“Matrix is soft”“Softening”“Matrix is soft”“Softening was notobserved”-

deformation in the area C. There were somedescriptions with time-dependent behaviour in thearea 1, 2, B and 3. Therefore, we could estimate that
there was some potentiality of time-dependent
deformation in these areas, though there was somepossibility to overestimate time-dependent behaviour.
There was no description with that in the area A. It
might be difficult to predict that time-dependent
deformation would occur in the area A.

TP=63,292-63,314: No
groundwater
TP=63,314-63,364,: 24
TP=63502: 80
TP=63,516: 130
TP-=63,528: 100
TP=63,542: 50
TP= 63,557-63,570:
firstly 600, finally 170
TP= 63,581-63,587:
10.8
TP= 63600- 63660: No
groundwater inflow--

and result in time-dependent deformation of these
sections.
By attaching importance to descriptions withregard to time-dependent behaviour and groundwater,
we could estimate that where had a risk oftime-dependent deformation, and could judge tochange tunnel support pattern to avoid
time-dependent deformation.
5.

Groundwater inflow was described in the area 1,
A, 2, B, 3 and C (1st Repair), while no descriptions
for that in the area 4, C (2nd Repair) and 5.
Remarkable groundwater inflow was observed in thearea 2 and 3, between the area A and B, and the area
B and C, respectively. Though rock of the area A, B
and C was originally dry or under stable
circumstances of groundwater, it may become wet or
become under unstable groundwater conditions bygroundwater inflow from the area 2 and 3 after tunnel
excavation. That might strengthen rock degradations,

Conclusions

In this study, records of construction and repair ofa tunnel with time-dependent deformation in
Hokkaido were correlated with each other to develop
judging method of time-dependent deformation. The
results obtained in this study led to the following
conclusions.
1) Most parts of the tunnel were not inverted
when score of face estimation is less than 20, andtime-dependent deformation of the studied tunnel
occurred only in non-inverted parts. In such parts,

6

10th Asian Regional Conference of IAEG (2015)displacement value of deformation part tended to belarger than that of non-deformation part. Though theboundary value was too small (about 4mm of crownsettlement) to be adopted as a threshold to determine
tunnel support patterns, there is a possibility that thevalue could be used for screening to find the part oftime-dependent deformation in similar geologicalareas.
2) Convergent time of time-dependent
deformation section was found to be less than about
80 days. That suggests that rock degradation byrelease of in-situ stress of rock might end less thanabout 80 days, and time-dependent deformation
occurred by other factors such as mineral change inrock by groundwater inflow or other conditionchange of temperature and air.
3) As there were many descriptions oftime-dependent behavior in the area C, we could
easily estimate that there was a large potentiality oftime-dependent deformation by only taking them into
consideration seriously. As there were some suchdescriptions in the area 1, 2, B and 3, we could
estimate that there was some potentiality oftime-dependent deformation although there was somepossibility
tooverestimate
time-dependent
deformation. For the area A without suchdescriptions, it seems to be difficult to predict thattime-dependent deformation would occur. By
attaching importance to the descriptions oftime-dependent behavior, we could mostly estimatethat where had a risk of time-dependent deformation,and changed tunnel support pattern for that.
4) Remarkable groundwater inflow was observedin the area 2 and 3, between the area A and B, andthe area B and C, respectively. Though rock of thearea A, B and C was originally dry or under stable
circumstances of groundwater, it may become wet or
become under unstable groundwater conditions bygroundwater inflow from the area 2 and 3 after tunnel
excavation. That might strengthen rock degradations,and result in time-dependent deformation of these
sections.

Ministry of Land, Infrastructure, Transport andTourism. We would like to show our heartfelt
appreciation. This research was implemented withsupport from the “Construction Technology Researchand Development Subsidy Program” of the Ministryof Land, Infrastructure, Transport and Tourism forthe “Development of Geological Evaluation andDiagnostic Techniques for Deteriorating Tunnels
with Deformation”.
References
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Meeting of the Japan Society of Engineering
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Murayama, H., Niwa, H. & Ito, Y. (2015): Project
study of tunnels with time-dependent behaviour–Records of planning and construction, Proceedingsof the World Tunnel Congress 2015, Croatia.
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Niwa, H., Murayama, H. & Okazaki, K. (2015b):
Project study of tunnels with time-dependent
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2015, Croatia.
Okazaki, K., Niwa, H., Murayama, H. & Ito, Y.
(2015a): Consideration of the mineralogicalcharacteristics and time-dependent behavior of thehydrothermal altered andesite, Proceedings of the
43rd Symposium on rock mechanics, pp.170-175 (inJapanese).
Okazaki, K., Ito, Y., Niwa, H., Murayama, H. &Sasaya, T. (2015b): Project study of tunnels with
time-dependent behaviour –Geochemical andmechanical characteristic of rock mass, Proceedingsof the World Tunnel Congress 2015, Croatia.
Oyama, T., Chigira, M., Ohmura, N. & Watanabe, Y.
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Acknowledgements
We would like to express our appreciation to the
Study Committee on Measurement Technology for
Tunnel Deformation Surveys for helping us with thecomplication of the research results by providing
valuable opinions. Also, regarding investigation, we
received a great deal of cooperation from those at the
Hokkaido Regional Development Bureau of the7