An analytical model for the grouted rock bolt in NATM tunneling design is proposed. Typical distributions of axial loads are presented considering the debonding at the interface between rock bolt and rock mass. The parameters study shows that: 1) The position of maximum axial force is not only related with the length of rock bolt and internal radius of tunnel, but also strongly influenced by physical properties of rock mass. 2) Maximum axial load and its position in rock bolt tends to be constant when anchor length of bolt is long enough, which means it is not good only to increase the length of rock bolt under certain condition. 3) Young's modulus of rock mass influences the working of bolt significantly.

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On the basis of a refined Shear-lag model, a constitutive equation is proposed to estimate the axial force of rock bolt according to the displacement of surrounding matrix. Coupling and decoupling behaviors of reinforcement in pullout tests, around an underground opening and opening joints are discussed respectively. For pullout test, the distribution of axial force and shear stress is compared with former research and test results, and a back analysis method is suggested to estimate the shear strength of the interface and the ultimate capacity of the rock bolt. As an example, the behavior of rock bolts intersecting multizone around a tunnel is analyzed, and the neutral location of rock bolts is discussed further. For a rock bolt intersecting joints, more than one neutral point may appear according to analysis.

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Generally, the bench cut excavation is adopted in squeezing rock. However, advancing drift is used as auxiliary method for the occurrence of large-scale earth pressure in Nikkureyama Tunnel II. This paper studies field measurement data of, Nikkureyama tunnel II. It examines the effect of bench cut and advancing drift by using 3D-FDM. Also, it proposes optimum drift length and bench length from the above result.

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In tunnel construction, the phenomenon in which displacement becomes large is the result of plastic deformation of the surrounding natural ground of tunnel. We reported that the case is remarkable case where a competence factor (the competence factor is the ratio of unconfined compressive strength to initial stress) is less than 2 and an internal friction angle is less than 30 degrees, according to arrangement of the past example of construction by NATM and numerical analysis etc.
In this paper, as a method of evaluation the generating conditions and area of a plastic deformation in NATM, the function that uses the internal friction angle, cohesion, etc. as a factor was drawn. Then, the ratio of ground stability that is the reciprocal of a coefficient of stability is shown the effective factor that evaluates the grade of tunnel deformation. In the natural ground where a hard part, soft part and weak part are intermingled, due to the quality of soft and weak parts mainly influences the grade of the displacement at tunnel construction, it is important to evaluate as the whole of natural ground, from carrying out a tri-axial compressive test for estimating the factors (internal friction angle, cohesion, etc.), in order to evaluate the existence and area of plastic deformation.

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Buckling load and buckling mode of a tunnel arch in two dimensions using a circular arc model are presented in this paper. Buckling analysis is first carried out on the circular arc under the uniform external pressure; the analytical results are then compared with theoretical results in order to check the validity of the method of analysis. Further, buckling verification was done by carrying out experiments on tunnel arch model. The arch was then analyzed under the same experimental conditions and proved to be sufficiently safe against buckling.

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The seismic refraction method has been widely used in many tunnel projects in mountainous areas. However, it is sometimes difficult to apply this way to the complicated geological feature of Japan, too. This is said to be utilized efficiently and for there to be no limit and geology information on investigation.
Then, writers noted the point currently used abundantly in the construction stage evaluating cutting-face. And it was presupposed that adjustment of a geological survey is evaluated by the same item as cutting-face evaluation. After we evaluated three tunnels using this method, it was possible to judge about the high precision.

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The accelarated deterioration experiment of the specimen which modeled RC lining and SFRC lining with the bending crack was carried out. The corrosion of the reinforcement in ages 30th of the RC lining was measured, and the bending test for confirming performance of structure was carried out.
As the result, It was confirmed that invasion of chloride ions and progress of the carbonationto the crack inside were early by the exsistence of the crack over 0.1mm at the width. The corrosion of the reinforcement started by the infiltration of chloride ions in the crack inside. In the meantime, the dynamic performance of the reinforcement did not lower, even if the reinforcement corroded, ifthe age is 30th.

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Some number of cases where concrete pieces of tunnel lining exfoliate are paid attention to as a social problem. Repair methods for them have been studied and experienced. However it is thought to contribute to the future durability and safety to minimize damage of cracks as small as possible in a construction stage before starting operation. In the squeezing ground in particular, the damage on lining is quite remarkable compared with the normal ground.
This paper aims at suggesting a method of design of lining by the following analysis. Firstly relationship between deformation of ground, stress within lining and damage of cracks on the basis of investigation on lining in squeezing ground is examined and secondly the multivariate analysis is done which makes possible to predict damage of cracks before placing the lining concrete.

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The kinematic load model for conventional circular shield had been proposed, taking account of the construction records and the previous researches. In this paper, the kinematic shield model for DPLEX shield was proposed, modifying the above model. To validate the newly developed model, the DPLEX shield behavior due to cutter frame rotation was simulated by using the actual site condition data and the in-situ data on shield control during excavation. The obtained results were compared with the measured one. As a result, it was confirmed that the predicted DPLEX shield behavior due to cutter frame rotation has a good agreement with the actual one.

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It becomes very important to investigate the effects of fire on tunnel lining stability to avoid fatal damage. In this paper, two scenario fires followed by the accident of 26, 0001 tanker in the shield tunnel are considered. As the result of thermal analysis using a three-dimensional finite element method, themaximum temperature nearby tunnel lining is simulated 1026°C (100MW fire), and 1142°C (200MW fire).

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Tokyo Metropolitan Government has developed to apply the shield construction method with four-segmented three-hinged structure, which is suitable for construction of the main and the branch lines of Sewage re-construction plan, in the field. This segment is different from the conventional one with bolted joints. It has the hinge coupler joint which cannot resist tensile forces. Usually analysis for internal pressure is omitted for sewage tunnels. However, in this study loading tests for internal water pressure were carried out to confirm safety of the hinged structure in the case of unexpected level of rainfall and unbalanced loading conditions caused by construction in vicinity. The result of the loading tests confirms safety and watertightness of the tunnel in both cases

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The authors have been studying the prestressed precast concrete segmental lining that structural features are to introduce prestress by unbonded prestressing steels to radial and circumferential directions of shield tunnel lining. This paper reports that a computation coincides with a test result by various analysis trials which consider prestressing steel friction resistance in order to evaluate joint bending stiffness of a tunnel lining segment with unbonded prestressed concrete structure.

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Construction had completed on the world's first shield driven double track subway tunnel of rectangular shape for the Kyoto Municipal Subway. The tunnel has the crossover section, which does not have center pillars and the running track section, which does have pillars. The tunnel had passed through of the upper diluvial beds with a depth of cover of 8.2 to 14.4m.
This has been a report on results of driving and measurement. Furthermore the subject and the correspondence method of a flat abbreviation rectangle section shield are described through these.

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Although the flexible joint that consists of rubber gasket and PC wire, has been applied for the seismic joint of 8 immersed tunnels, that is insufficient in respect to the deformability for large earthquake movement or soil settlement Furthermore, long-term endurance of rubber gasket under high compression has not enough reliability.
The bellows joint made from steel, is a high deformable that joint used mainly in the field of piping. This paper shows the development of bellows joint adopted as the flexible joint for the immersed tunnel elements in lieu of conventional seismic joints.

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Pipe jacking is the one of the urban tunneling methods in JAPAN. This method might be more profitable than prevalent shield tunneling when the tunnel length is extremely short. However, the large diameter jacking pipe which is more than 3.0m i.d. has not been applied so far due to transport height limitation based on the Road Traffic Control Row. Therefore, the authors suggest that halved casting pipe enables easy transportation without any restriction and it can be combined by tensioning around a launch shaft then installed underground by jacking as same as a conventional method.
This paper concludes about the application of the halved pipe using prestressed concrete as a result of the basic performance test in compliance with the Japanese sewage jacking pipe specification.

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This paper tries to find how the difference of strain softening characteristics influences the deformation mechanism of ground around shallow non-supported tunnel by numerical analysis. The results show that it is possible to evaluate the onset and progress of deformation mode to collapse by a common criterion. This implies even if the details of strain softening characteristics are not known completely, the outline of deformation mechanism can be defined with ease, which provides useful information for field engineers.

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This paper describes centrifuge model tests concerning tunnel deformation and stability on condition that overburden height is small and ground strength is small. Model tests procedures are followings. Model ground with tunnel (φ95mm) in ground was made by soil cement that strength was qu≈250kN/m². After model preparation, centrifuge gravity was increased until failure. The main results are as follows.(1) Settlement of ground surface increased with rising of centrifuge acceleration.(2) The collapse above of the tunnel was observed when model overburden height reached about 7-10m.

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Tunnel collapses due to various reasons according to the state of ground and excavation conditions and condition of support. It is very difficult to predict and evaluate them and prepare the strengthening in advance.
This study deals with development of the prediction system of tunnel collapse magnitude and analysis of the causes affecting the magnitude of the collapse.
Based on the analysis of data in this study, the main cause of collapse magnitude, which is the output node, is topography around the tunnel.

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One of the method for predicting surface settlement at next tunnel-face is that convergence curve are estimated using three types of curves, advancing rate, stress release and ground characteristic based on in-situ monitoring. In this method, point-symmetrical growth curve is generally adopted as stress release curve (SRC) especially in 2-D analysis. However, it has been obvious that the SRC computed by 3-D analysis has resulted in non point-symmetrical curve. The purposes of this study are to use the Gompertz's curve as non-point symmetrical growth curve to predict the surface settlement in 2-D analysis and to verify the validity our method in comparison with field data.

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In Takadayama-tunnel, the long facebolting by means of the friction anchored rockbolts is adopted as the stabilization measure against face collapse. In order to estimate the effects of rock reinforcement with long facebolts, we measured the axial forces of long facebolts during excavation.Numerical simulation of the measured axial forces was performed by means of three-dimensional excavation analyses; and it successfully expressed the behaviors of measured axial force distributions of the facebolts as well as other tunnel measurements. Furthermore, the numerical analyses with and without facebolts were performed so as to investigate the reinforcing effects.

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A magnetic anisotropy sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material is measured in a nondestructive manner, which then can be translated into the absolute values of stresses existing on the surface. This technique was applied to measure stresses of H-beams, used as tunnel support structures, to confirm expected measurement accuracy. The results show that this method could be one of the promising technologies for non-destructive stress measurement for safe construction and probably maintenance of rock structures.

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This paper shows the enlarged tunnel supports prediction based on TBM-driven pilot tunnel data and shows its result. The collected data for prediction analysis are the TBM machine data, the observed geologic data and the TBM tunnel construction records. The applied tunnel is Suzuka Tunnel that is wide section for new expressway constructed between Mie Pref. and Shiga Pref. in central Japan. Its geology consists of granite and sedimentary rocks. As a result, the ratio of tunnel supports agreement length is 81% at present. This shows that the TBM-driven pilot tunnel data can be extremely available for wide tunnel construction.

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Proper tunnel support which is suitable for ground condition should be selected for safety and economical construction. Method of selecting support is mainly based on the past experience and the observation and measurement data in excavation should be used for the judgment of ground condition. In this study, impact values for face observation item calculated using cluster analysis and their tendency was examined. It was found that the values were different between rock characteristic and it may be possible to classify much clearly using the value calculated by cluster analysis.

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In recent year, NATM is demanded to construct of tunnel under this severe condition, such as soft un-harden ground and expansive ground. In such a case, examination cases by the numerical analytic model have been increasing. This research examines how these parameter are expressed by the numerical analytic for an plasticity natural ground paying attention for ‘ cohesion’ and‘ angle of internal friction’.

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Kitasuma Tunnel is the longest twin bore tunnel with a center-pillar which has been rarely constructed in Japan. Because lkm long tunnel bored just beneath a residential area, the design of the center-pillar is an important consideration. Based on result of F. E. M. analysis, auxiliary method with pre-grouting and PU-IF were applied before excavation forsupporting ground surface. Rock Split method were applied for boring in the middle part, very hard rock area. In this paper, the basic idea of the design and construction for twin bore tunnel based on the result of measurements is mentioned.

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The both portals of Shizuoka 3^rd tunnel is located the steep slope. So the access tunnel (42m²) was required and diverge the main tunnel (180m²). This report reports on the design and the construction of the large section divergence.

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At penstock construction (sectional area 17m², length 140m and 48 degrees) in Omarugawa power station, we construct it by enlargement excavation used blasting after pilot excavation by Raise Borer method (2.44m-diameter). In the case of its system, it is important to obtain information about geological state at pilot excavation. Then, we grasp summarily rock mass state at inclined shaft, and try to guess support pattern by analyzing excavation data by Raise Borer. And further, we verify its technique by seismic prospecting

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Fracturing system employing the shock force by electric discharge method was applied as a technology that excavation of crosscut of the expressway tunnel for emergency cars.This technology is fracturing system for rockmass by expansive pressure of sudden melting and evaporation of the wire with electricity of the high voltage. Effective and safety construction could be done by the application of combination of this technology and breaker without giving a neighboring section a bad influence.

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Face bolting is one of the effective methods to stabilize tunnel face. This paper will describe that development of new type of face bolting using Glass Fiber Reinforced Plastic tube. Some drilling tests have been performed in various geological conditions, and have been evaluated drilling applicability.
Pull out tests have been also carried out to evaluate the bonding properties of GFRP face bolts.

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Kawarayu tunnel in the JR Agatsuma line is a single-track tunnel, newly under constructing along with the substitution construction of present Agatsuma line, which will be going under water by the construction of the Yanba dam. Geological features in the most part of the tunnel is andesite with high strength, but there is a weakness part which consists of the andesite boulder deposit that fell from upper part when andesite lava was extruded. In this paper, we describe the grouting and steel pile forepiling for ground stabilization taken in this andesite deposit layer section.

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The mountain tunneling method has recently been adopted in an increasing number of cases in urban areas. There have, however, been few cases where complete watertightness was achieved, which resulted in massive repair and increased life-cycle cost. Our company developed new waterproofing technology that provides a “ watertight structure that does not prevent concrete filling and is in close contact with the shotcrete”. The technology enables the construction of a highly watertight structure that is applicable to urban mountain tunnels. Applying the technology is expected to greatly improve the quality of waterproofing systems and linings not only in urban watertight tunnels but also in ordinary mountain tunnels. This paper describes the application of the technology at the Minaminagareyama Tunnel.

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This paper reports the face stabilization measures used for the tunnel running under the diluvium upland. The geology comprises sand, volcanic ash silt and cohesive soil. Since the groundwater level is high, deep wells are dug. On the other hand, as the measures for tunnel excavation in unconsolidated ground, the crowns are reinforced by forepiling or the AGF (forepiling with injection). These measures had been devised continuously, in response to the change of the face condition such as the water flow from face and the appearance of a sand layer with a small coefficient of uniformity in the crown.

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This report describes one of the appropriate methods for excavating a shallow tunnel. The tunnel mentioned here is excavated by NATM with soil stabilizing method in that the ground over the face was stabilized by cement in advance. There is little restriction for using the land above the tunnel and this method is more economical than the other methods. The shallow mixing method and the pre mixed method are used appropriately for the improvement. From the result of measurements and FEM analyses, it is considered that the face stabilization is improved by the method, and therefore, it is possible that the supports are reduced.

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Hida tunnel is a 10.7km long highway tunnel. It has been excavated by a large cross section NATM in poor ground with high overburden (more than 600m now). This excavation method will be continued to the planned boring commencement location of the 12.84m diameter TBM.
A large displacement during the main tunnel excavation in poor ground was anticipated. Using the measurement data of the pilot tunnel in this section, the initial support system structure and its displacement of the main tunnel during excavation were analyzed by F. E. M. and its results were applied to the main tunnel execution. The excavated tunnel section of each stage was closed with temporary invert at adequate timing, if its displacement is anticipated to be larger than estimated value. The combination of measuring, numerical analysis and feed back of measured data to the execution method made the actual displacement of the main tunnel smaller than estimation successfully.

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In HIDA pilot tunnel, the hydraulic head pressure which is equal to thickness of earth covering is confirmed by boring, as the rock pressure is increasing due to high earth covering which is 1000m. By using a double steel pipe, geology ahead of the tunnel face could be investigated more. Large-scale crash was avoidable with the AGF method of construction. The prior measure and construction situation, which were carried out by TBM in a lot of groundwater, are reported

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The Aki-Fuchu twin tunnels on the Hiroshima Expressway No.1 have two lanes each, with 30 to 40 m overburden. The geology of that region is composed of heavily weathered granite and diorite, which are extremely decomposed due to deep weathering. Therefore, the tunnel face is unstable and the convergence is noticeable. For ensuring face stability, tunneling is advanced with long face forepiling using glass fiber reinforced plastic tubes. The long face forepiling has found wider applications these days. However, almost no quantitative measurement data are available at present. In this context, the authors determined the ground behavior by measuring the axial force in the long face forepiles and the displacement ahead of the face, and quantitatively evaluated the effect of this technique by conducting numerical analysis.

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The Wakunami Tunnel is a binocular tunnel on the Kanazawa Sotokan Expressway. An approach-lane tunnel runs just above this binocular tunnel. This is an unprecedented structure in Japan. There is a residential zone on the surface, and the overburden is only about 12 m. In addition, the distance between the binocular tunnel and the approach-lane tunnel is merely 3 m at minimum. These severe restrictions are imposed on this tunneling project.
For construction of the binocular tunnel, a new method, named Pre Supporting System- Arch (PSS-Arch), was selected using a value engineering approach after conclusion of the contract. This method installs curved steel pipes from the central drift. This report deals with the development and construction method of this new technique.

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The basic excavation methods to be used in the New Tomei Expressway tunnels are the method of upper heading and bench in locations where the ground is relatively good, and the method of upper heading and bench with a center pilot in the upper heading in locations where face stability is poor.
In addition to these excavation methods, the TBM Pilot and Enlargement Excavation Method is to be introduced as a new excavation method for the New Tomei Expressway tunnels. With the TBM Pilot and Enlargement Excavation Method, by performing a pilot excavation by TBM within the tunnel cross section in advance, various beneficial effects such as confirmation of geological conditions and drainage into the pilot are expected, so that safe and efficient enlargement excavation can be performed.
This paper describes evaluation of beneficial effects for the TBM Pilot and Enlargement Excavation Method in large scale tunnels.

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Higashiyama Tunnel is a twin highway tunnel having two lanes each which passes through under unfavourable ground conditions at a shallow depth of cover beneath densely residential area in the eastern part of Nagoya City. In order to preserve the residential environment, especially to restrict surface settlement, the tunnel supporting systems were designed containing a combination of up-to-date supplementary tunnelling techniques. During the tunnelling procedure, a construction monitoring programme was implemented to evaluate the adopting tunnelling methods, to predict the ground behaviour and to assist in the revising of construction methods for further excavation. This paper describes the tunnelling method adopted in urban area and the analysed results of the ground behaviour induced by tunnel excavation.

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The Kanaya tunnel in the New Tomei Expressway employed the TBM pilot-tunneling method is under construction. These tunnels with large cross sectional area, in general, cause large deformation at the foot of top heading due to the stress concentration. In particular, the zone where the overburden depth is about 300m in mudstone layer demonstrates excessive displacement more than 100mm without convergence tendency. Considering the restriction of excessive internal and foot displacement and the reinforcement of the surrounding ground, the high tensigle strength bolts instead of rock bolts are introduced on the circumferential arrangement.
This paper describes the results and applications of the high tensile strength bolts as the countermeasures for the excessive displacement.

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As for the rock-mass classification, the JH method becomes mainstream recently. However, that is not fit enogh for the complicated geological feature which called an accretionary zone, because it is the “ standard” rock-mass classification covered Japan all.
In this paper, the rock-mass classification fitted for the complicated geological feature has been investigated with in-site data.

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The movement on the way to make ground arch inside the tunnel after excavation has been regarded as what offers the most appropriate data to grasp the balance of ground and tunnel support of NATM. Generally, we have been surveying the displacement of inside cross-section with a displacement seismograph in the ground and also the stress of tunnel support at a crown or side walls.
Now we have used the rock displacement and the stress of tunnel support to estimate the stability of the structure. At Shizuoka the third tunnel on the New Tomei Expressway, we have used various parameters like change of voltage, temperature and AE after excavation.
We report the result of the field test about the method we have never applied to the tunnel and the possibility of the assessment with this analysis.

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Iiyama tunnel has bored into Tertiary sandstone, mudstone and tuffbreccia which include inflammable gas like methane gas, at boundary of Nagano and Niigata prefecture. For methane gas is very combustible and explode easily, investigation and monitoring of inflammable gas is very important for safety construction of the tunnel. It was reported that horizontal exploratory boring, automated monitoring system and ventilation system for dilution of the gas were applied effectively on this tunneling.

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The construction of Fujikawa tunnel requires auxiliary method for the enlargement after TBM drift. Several types of auxiliary method were examined by 3-dimension numerical analysis called FLAC 3D in order to select the appropriate one according to ground condition. As a result, the behavior of tunnel under enlargement was evaluated including the support effect with auxiliary method. Applying them to the actual tunnel site the validity was verified based on the field observation.

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The Nagata tunnel in Kobe city 2 nd highway line had been carried out by Umbrella Method. Because it was under densely residential area, shallow depth of cover and watercontained unsolid ground. In this report, it is mentioned regarding the selection of Umbrella method developed by the result of trial section, the behavior and consideration of long forepiling, the ground and sup-ports, and the simple prediction method of ground settlement evaluated by the measurement results.

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Construction of the eye-glass-frame tunnels with a center pillar, which stand very close to each other, tends to increase because of limitation of the land utilization in Japan. Compare to the total number of the tunnels, there are not many constructions of the eye-glass-frame tunnels with a center pillar. In design and construction stage of this tunnel type; it is needed to understand sufficiently the characteristic such as displacement action of the periphery natural ground. This paper used measurement data for statistical analysis to study the influence on ground surface settlement during the construction stages.

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The Mori-Shisen tunnel located at Isogo-ward, Yokohama-city is a twin tunnel with center pillar. Its length is 164m and cross-sectional area is 121 m². Since overburden is low and structures exist on the surface, auxiliary methods of construction, such as a Trevi-tube method and horizontal jet grouting at leg level, were applied for the purpose of controlling subsidence at the surface to the minimum. Moreover, construction was carried out carefully performing measurement managements and reverse analysis. Reverse analysis was performed using 2-dimensional FEM based on measurement results. Consequently, construction was accomplished successfully without any serious impacts against surrounding structures. This report describes various kinds of measurement results and reverse analysis results at the time of tunnel excavation.

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The performance of the cable bolting system pre-installed in the pilot tunnel has been investigated. From the measurement results following two facts were clarified. 1) There was the generation of the axial force in cable bolts and they contributed to the stabilization of the face in the main tunnel. 2) It was possible to use the cable bolting system as a supporting member in the main tunnel.

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Full-scale model tests simulating tunnel concrete lining were carried out to clarify collapse mechanism of tunnel lining under a few kinds of load condition and reinforcing material. For the design of tunnel lining, the limit states of lining cross section were defined, however, the limit state of the section was found to be different from the structural one. Load-carrying capacity will be calculated more rationally and it leads to proper structure, reduction of construction cost and improvement of its durability by considering these results for the design.

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High performance shotcrete with high early strength, over 3 N/mm² after 10 minutes, has been developed for improvement of safety and application of high-speed excavation. High strength additive and super self-hardening acceralator, together to form ettringite, are applied to high quality shotcrete, which is achieved by adoption of two-stage mixing, known as SEC method, and usage of silica-fume, limestone fine-powder. Both table tests and shotcrete experiments in a model tunnel are described.

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