This study is to quantitatively clarify the mutual influence due to the adjacent excavation near to the existed tunnel by using the base friction model test and the finite deformation difference method. The varied factors included the mechanical character of the ground, the nearness and depth of tunnels. In order to reduce the influence to the existed tunnel, the reinforcement method of pillar between double tunnels is suggested through systematic bolting, and the supporting and stabilizing effect on the extent of failure zone and deformational behavior of surrounding rock mass and pillar is investigated in detail, by changing the pattern and length of grouted rockbolts, according to the distance of adjacent tunnel centers and the competency factor of ground.

View full abstract

This paper presents rock mass classification technique by resistivity-based high-density prospecting data in the mountain tunnel. In the proposed technique, seismic wave velocity based on resistivity is converted by using the theoretical relation between electical resistivity and seismic wave velocity which is the function of porosity. The authors carry out rock mass classification by quantitative evaluation of ground resistivity basing on resistivity measurement results of cores collected on cutting face of roadway tunnel site. Furthermore, the applicability of the proposed technique is discussed, by comparing estimated support patterns with actually performed ones.

View full abstract

In TBM tunneling, the installation of segmental liner, which can support both thrust force for the machine and earth pressure for tunneling, is effective for safe and rapid excavation when the rock is weak and/or the excavated roof collapses frequently. This paper describes the development of new type segmental liner that is relatively cheap and easy to install compared to the conventional segments for shield tunneling.
The liner has composite structure of steel shell and filled concrete. Each pieces are jointed without using bolts to reduce installation time. In order to establish the design method for this liner, loading tests on full scale pieces were performed and the results were evaluated using numerical analysis.

View full abstract

Newly developed mobile tunneller (MM130R), incorporating both the power of hard rock excavation of the TBM and the mobility of the roadheader, has been firstly applied to the hard rock excavation of Takatoriyama tunnel project in Rokko mountain area. In this project, the study on the tunnel stability considering the spherical face effect has been carried out by numerical analysis using FEM and field measurement of loosen zone ahead of tunnel face using seismic prospecting. Then the rational support system has been proposed and its effectiveness has been validated by comprehensive observational method at in-situ. These results will be useful for the next tunnel projects in the near future.

View full abstract

“Pre -reinforcement behind the face” using long steel pipes and consolidations, known as umbrella method, is a technique which has been widely used in the last few years, since the tunnel has to be constructed nearby urban area where the environment protection is severely restricted. Although the fact, we have had few data regarding the method and haven't grasped the real effect of it yet.
This paper presents some notes of TREVITUB method, one of the umbrella method, by adapting it to the small overburden and loose soil tunnel construction. Moreover, focusing on the behavior of the steel pipes, the authors discuss about surcharge on the pipes and the design model of the method.

View full abstract

This study presents two basic considerations to evaluate the periodic change temperatures at planning tunnel. In this study consists of the following two topics, one is identified to the periodic changes from the observed temperatures, and the other is estimated at the site of non-observed temperatures using the Kriging method. In the former study, unknown parameters in the mathematical formula are identified in order to obtain the characteristics of temperatures. In the latter one, the non-observed site temperatures are estimated in the Kriging which is interpolating technique on the assumption of the spatial correlation of estimated variables, and which is framed by stochastic theory. Finally, Numerical examples are worked out to demonstrate the usefulness of these methods for estimation of the temperatures.

View full abstract

In order to reduce the construction cost of a shield tunneling, it is required to develop the rational segment structure. We have studied and developed “bolt-boxless Flat Segment” which has no exposed metal connectors in the internal surface of the lined area. By applying this segment to shield tunnel, it will be possible to omit secondary linings. This paper describes the concept of bolt-boxless Flat Segment and estimates flexural and shear rigidity of joint based on the result of segment loading test. From the test results, it is confirmed that flexural rigidity is different in response to the shape of joints and the numbers of metal connectors.

View full abstract

Multi-faced shield tunnel method can construct plural tunnels at a time and therefore it has an advantage of enhancing safety and shortening delivery. However, its posture control is complicated because of the unbalance in cutting torque caused by the existence of plural cutter faces and of the relatively highly situated gravity centre of the shield machine. To cope with these problems, a vertically doubly-faced shield machine with articulate mechanism was manufactured on trial and the real ground excavation was carried out at field. It revealed the characteristics of its posture change as well as the effectiveness of proposed evaluating method of reaction force at the cutter face and rolling characteristics.

View full abstract

A shield tunnelling method which permits continuous excavation of a vertical shaft and a main tunnel to considerable depths is beginning to be introduced in the Metropolitan area.
This is a study on coupled FEM analysis performed to investigate the effects of shaft excavation on the mechanical and hydraulic properties of the ground that vary between the said method and conventional techniques, most typically the pneumatic caisson metod. The analysis revealed that the method prevents shear strains due to main tunnel excavation from concentrating in shaft-main tunnel junctions, and thereby decreases a likelihood of local stress concentrations occurring in these sections.

View full abstract

Recently, flat cross section tunnels have often been adopted on NATM. This tunnel is also a flat cross section tunnel. And Standard combinations of tunnel supports are adopted. It seems, however, that behavior of flat cross section tunnel is different from that of circle cross section tunnel.
Therefore using the results of measurement A (routine observations and measurements) and measurement B (measurements to be supplemented according to the ground condition), the authors grasped the characteristics of behavior of flat cross section tunnel.

View full abstract

This study present basic consideration to evaluate the thermal behavior in road tunnel-ground. In this study, the extended Kalman filter which was incorporated with the one-dimensional finite element thermal analysis in order to identify unknown the thermal coefficients in tunnel-ground. And then, the estimated in tunnelground temperatures from identified the thermal coefficients are compared with the observed temperatures of actual tunnel-ground. Finally, numerical examples are worked out to demonstrate the usefulness of this method in identification of the thermal characteristics and evaluation and/or estimation of thermal behavior in road tunnel-ground.

View full abstract

An experimental investigation was conducted to observe fundamental deformational behaviours of parallel tunnels as a function of central wall width B, overburden height H, and tunnel diameter D. The experimental apparatus used here simulates tunnel excavation by reducing pressure of dual air-bags which represent two adjacent tunnels constructed within alminium bars. Failure modes, pillar stresses, air-bag pressures at collapse, etc. are monitored during experments wherein pillar width and overburden height are varied for parallel tunnels having diameters of 15cm. Results are compiled with regard to a relationship between B/D and H/D, showing the existence of a transition zone which identifies the onset of a failure mode, which is characterized by collapse of pillar and subsequent formation of a loosen zone involving both tunnels.

View full abstract

TSP survey is one of the geophysical explorations for estimating geology ahead of a tunnel face by using the seismic wave.This survey has the advantage of being able to carry out in short time, so that it has been in practical use under construction.However, the survey requirement of TSP is often restricted depending on the situation in the tunnel.So we examine the requirement in regard to a method of TSP survey by on-site testing with the aim of obtaining the fundamental data to decide the source-receiver configuration in that situation.The result of this examination is as follows.(1) A better result is obtained by using a higher speed explosive at sources.(2) In case of the more shot holes or the longer offset distance, the relatively better result is obtained.

View full abstract

TSP (Tunnel Seismic Prediction) method is a kind of geophysical exploration method in tunnel, and it employs seismic wave refrections to explore fault fructure zones and giological boundaries ahead of tunnel working face. Some statisical examinations for accuracy of investigation were curried on using data which were measured in some tunnel construction sites. The distance between face and objects (ex. fault, intrusive rock or giological boundaries), the angle between objects and tunnel axis and condition of objects were discussed for cause of error on the method. The summary of the results is:
1) In the ordinary giological condition, the error range is ±5m.
2) Erorr range were influenced by the angle between objects and tunnel axis or condition of objects.
3) It will be able to estimate the giological structure from patterns of wave reflection.

View full abstract

During the excavation phase, abrupt changes of geological condition often bring about accidents which cause delay in tunnelling progress. Therefore, the tunnel engineer requires the information of geological condition ahead of the face. Ordinaly this imformation is obtained from surface investigations and face observations. But these cannot get correctly imformations ahead of the face. So it is required and investigated the prediction methods ahead of the face.
In this paper, we take two prediction methods [TSP (Tunnel Seismic Prediction), non-core horizontal boring test] and make a field experiment. In this experiment, we examine the relation between rock classification and two prediction methods, and the applicability for tunnel site.

View full abstract

The fore survey system of tunnel face using hydraulic drilling was developed to estimate the geologic conditions ahead of the tunnel face. In this study, the data of drilling composed of damping, rotation and percussion pressures have been compared with Rock Mass Classification, and physical value (strength) of rock mass or specimens.
From this comparison it has been made clear that the data of damping pressure closely correlate with the properties of rock mass. As a result that the fore survey system on the basis of this relationship has been applied in tunnel, each location of the faults in thickness about 20 cm could be estimated.

View full abstract

Ground penetrating radar has been effectively used for tunnel survey. Tunnel lining is mostly made of concrete. Huge data from the surveys have shown that the dielectric constants of lining concrete almost vary 9 to 12. However, a dielectric constant at a location for calibration has been calculatedto be incredibly small. That disagreed with our statistical common sense. After investigating repeatedly, no error has been found. It can be imagined that water content of brick must be changed more easily than concrete. Though experimental analysis is needed for proof, the actual feature of brick must be kept in mind when analysis of tunnel survey by GPR is carried out.

View full abstract

Block Theory is available to estimate the position and scale of keyblocks in rock masses and evaluate their stability for supporting to protect surrounding rock mass from progressive failure. However, in engineering practice, it is not enough for engineers to evaluate them by utilizing Block Theory because of lack of accuracy for geometrical data.
In order to solve this problem, the authors propose the assessment system of keyblock stability by using non-destructive testing method. In this paper, we demonstrate its applicability to rock engineering based on the results of two model tests. Consequently, it is quite effective to keyblock stability problems.

View full abstract

Various studies is done effect for product of grouting steel pipe forepiling. But, for it being difficult to assume behavior of ground of face front at design stage, establishment of effective design technique is late in practical use by present situation. In this report, it is described the improvement type grouting steel pipe forepiling that was developed for the purpose of not enlarging face and supporting with members of equal size. And some consideration is described with measurement results about bending behavior of the steel pipe which is the subject of the forepiling.

View full abstract

Abo ventilation shaft had been excavated in November 1995. It has 7.5m in the diameter and 450m in the depth below surface, which is one of the largest shaft in Japan. This shaft connects two horizontal tunnel at the bottom, one is for ventilation and another is for drainage. This connecting section has been expected to take a complicated mechanical behavior during excavation. So we had conducted a numerical simulation using 3- dimensional Finite Elemental Analysis. This simulation has revealed that the shaft driving during connecting section makes the significant damage for the tunnel lining and rock masses around the horizontal tunnels. And this is also required the field measurement in order to estimate the stability of this section. This paper presents the typical mechanical behavior of such complicated connection section given by field measurements.

View full abstract

Recently multiplicity of support system are applied for national highway tunnels under the orders of Japan Highway Public Corp. Therefore it becomes more important to estimate rock mass behavior quantitatively at excavation, especially it related to rock mass cracks and heterogency. Then we examined the applicability of various rock mass classification for design of the tunnel support structure based on the face observation at HIWA tunnel. The face observation was changed to numerical data by RMR, RSR, Q-system and JH estimating quantative rock mass classfication.
Consequently in order to design tunnel support structure using the numerical face observation point, we must set up different importance for rock classification element by the kind of rock or by the geological condition.

View full abstract

More than ten cases of upheaving pavement in tunnels managed by JH have been observed. It seems rational to suppose that the reason for upheaving pavement is the omission of invert concrete. In those cases, there seemed to be no problem on long-term stabilization of tunnels therefore invert concrete was not required since the displacements were very small and faces were stable during tunnel construction period.
In order to clarify which kind of physical values of ground are needed for judgment on the necessity of invert concrete and what amount of them should be adopted as the guideline, we performed a case study on the deformed tunnels as well as researching related literature and questionnaires submitted by those who had been involved in the cases.
As the relation between the physical values of ground and upheaving pavement has been studied, we report the results on this paper

View full abstract

Forepiling has found wider application recently for restraining the tunnel crown settlements. However, the working mechanism of forepiles have not yet been well understood. In the construction of a diversion channel of the Katabira River, we placed forepiles as auxiliary means in the tunneling practice by the NATM with side drifts, and evaluated their displacement-restraning effect by measurements. The bedrock of this site is characterized by the fact that almost no displacement occurred ahead of the face. This paper poses a problem about the stress relief ratio to be included in two dimensional analysis for predicting the behavior of grounds presenting such displacement characteristics.

View full abstract

Recently, cable bolts have been used to reinforce the stability in a tunnel face. However, the support effect of the cable bolts installed in the tunnel face has not been made clear quantitatively. The field measurements concerning the axial force in cable bolts and ground movement in the tunnel face followed by the excavation were carried out. In order to evaluate the measurement results, three-dimensional numerical simulation using finite difference method was also performed. This paper will quantitatively examine the behavior of the tunnel face caused by the excavation and the support effect of the cable bolts installed in the tunnel face by comparing both results of field experiments and numerical experiments.

View full abstract

As the result of the increased importance of underground openings in traffic systems and/ or energy systems, there is an increasing need for a rapid and safety tunneling method. The cable bolt is one of the capable and powerful supporting measure for its purpose. But the functional mechanism of cable bolts is very complicated. The mechanical behavior of rock masses is extremely complex. The strength and deformability of them entirely depends on the system of discontinuities, such as cracks, fissures, faults, and bedding characteristics along these discontinuities. It may be thought that installing the cable bolts makes the mechanical behavior of rock masses drastically changed. This is named'Supporting Effect' in engineering sense. Hence, the supporting effect of cable bolt depends on the behavior of rock masses around the installed cable bolt. In this paper we discussed the relative behavior between rock masses and cable bolts on the basis of the result of field measurement. The effect of cable bolting also discussed.

View full abstract

with such problems is called “Vertical Forepoling Bolt Method”. In this method, the bolting are driven at regularinterval from the surface before excavation in order to reinforce the cutting face and the ground. However, there were still no data clarifying the effectiveness of this method.
At this time, field measurements was carried out by verifying the effectiveness of this method. From the field measurement, nearly elastic behavior of subsidence was measured by “EL beams sensor”. And, it become clear that the effectiveness of vertical forepoling bolt method is different from the upper zone and the shoulder of the tunnel by “Sliding deformeter E” and axial force measurements.

View full abstract

One of the important subjects tunnel excavation to keep the stability of tunnel face. When We counter the unstable geological condition, however, it is difficult that stable estimation of judgement to do additional support systems. We carried out three kinds of in-situ mesurements, it means Schmidt hammer test, Needle, penetration test, Simple seismic prospecting about all faces on the tunnel. Based on these data, we studied the relationship of assisting methods adoption. As a result, these adoption are influenced by condition of joints and a relaxation of a tunnel face. And we saw that assisting methods adoption correlated closely with a result of a needle penetration test.

View full abstract

It is expected to develop the reliable reinforced method to decrease the surface settlement on the shallow tunnel in urban region. A new pre-lining method which can make the continuous arched body on the top of the face has been developed. A pre-lining method is effectual tunnel support by arch in a cross section.
The two dimensional model test was carried out to investigate the effect of this sturding prelining model. This paper describes the result of the model test.

View full abstract

One of the greatest advantages of applying TBMs in tunnel excavation is its rapid and continuous excavation capabilities. However, the research on the past TBM application in Japan has shown that many tunnel projects have failed to take full advantages of TBMs mainly due to the unpredictability of the underground conditions and imbalances between the efficiency of TBMs and mucking systems. In order to solve the avobe problems, this paper proposes an excavation system which combines a TBM, a TSP (tunnel seismic prediction), a mucking system using continuous conveyer, and a pilot boring machine. By studying an actual application of the proposed system to the Hakamagoshi-Johana Pilot Tunnel Project, the paper discuss its impacts on the improvement of the excavation efficiency.

View full abstract

In tunneling with the TBM, the loading test with the main grippers are often conducted to estimate the deformability of the rock mass. In this study, loading tests withgrippers ofa hooded tunnel excavation machine were performed. The elastic moduli of the rock mass were estimated from the loading-displacement curves based on the finite element analysis. The Young's moduli of the rock mass obtained from the gripper loading tests were discussed by comparison with the laboratory test results and the elastic modulus evaluated from the rock displacements mesured with an extensometer. The gripper loading test is useful in that the elastic properties of the rock mass can be approximately estimated without disturbing the tunnel excavation processes.

View full abstract

In view of the tendency for tunnels to increase in length and cross section area, the needs for efficient new excavation methods combining mechanization and rationalization are much desired.
In response to the needs, a test execution using a 3.5m diameter Tunnel Boring Machine (TBM) for a pilot tunnel was planned in the construction of a Yuda No.2 Tunnel.
We studied the effect of a pilot tunnel by TBM, referring to the results of the measurement data analysis by full face excavation.

View full abstract

This paper will compared advantages and disadvantages between the frame analysis, FEM analysis and composite structure analysis in modeling and analyzing the behavior of reinforcement structure of concrete lining of hard-rock tunnels under different conditions. The paper will find that the FEM analysis well models the development of cracks, thus providing more accurate prediction of inner reinforcement structure which increases resistance of tunnel lining by preventing cracks from developing. On the other hand, it will also find that composite structure method is more effective in modeling RC structure which potentially develops multiple number of hair cracks. Based on the comparison of the above three methods, the paper will finally propose the most effective choice of an analytical method for each of different sets of design conditions which a designer may encounter when designing a reinforcement structure of tunnel lining.

View full abstract

To clarify the deformed tunnel lining that has various countermeasures such as rock bolting, back-filling, inner reinforcing and etc., numerical analysis were carried out. Tunnel lining performance after cracking is estimated by frame analysis with assumed crack section stress flow. In the analysis, constant vertical and horizontal earth pressures were assumed and tunnel is being double truck tunnel. Consequently, estimation of deformed lining capacity with all countermeasures were successfully performed, and the increased capacity of the linings are discussed in this paper.

View full abstract

After the completion of Seikan Tunnel, maintenance at the undersea portion has been carried out by Japan Railway Construction Public Corporation.
Long term monitoring for deformation of the lining and seepage water is being per formed to assure the tunnel's safety. Three dimensional measuring system has been introduced for convergence measurement. The seepage volume that depends on pore water pressure is on the decrease since the tunnel's opening.
This paper mentions three dimensional measuring system by electro-optical distance meter, the convergence measuring results and the volume change of seepage water.

View full abstract

The large scale cavern with the maximum cross sectional area of 420m² and the length of 61m, which was used as the settling basin of sewage plant. was planned and constructed in soft rock. The cavern was excavated by side pilot drift method at the arch section and multiple bench cutting method at the rest. After arch excavation, additional reinforcing anchors were installed to support the loosened ground. In this paper, the design and construction method of cavern in soft rock is presented. Also, details of adopted reinforcing anchors and the results of field monitoring are described.

View full abstract

Recently many kind of face stabilized methods (example: forepilinng near-horizontal jet-grouting, precutting, reinforcement of the tunnel face using fibber bolts) were adapted for the tunnel excavation in the unstable face condition. Ground condition of the north portal of Miyauti tunnel was very weathered mud stone. The problems were occurred groundslide by the tunnel excavation and stabilization of the face. The reinforcement of the face using long fibber bolts was adapted. This paper was reported the results of the several measurements of the behavior of the ground.

View full abstract

Recently the umbrella-methods (example: forepilinng near-horizontal jet-grouting) were adapted for the tunnel excavation in the very difficult ground condition. Ground condition of the north portal of Nanngou tunnel was embanked 17years ago.
The problems of the tunnel excavation was stabilization of the crown. Therefore, the umbrella-method using steel pipes with cement grout was adapted.
This paper was reported the results of the several measurements of the behavior of the ground.

View full abstract

This paper reports on the construction of NATM tunnel crossing right under the existing railway tunnel on JR touhoku line.
For operating JR Touhoku line safety, we are measuring the displasement of tunnel profile, joint of lining concrete and axial stress of rock bolt during excavating new tunnel. The measurement have been controlled by limiting value determined by FEM analysis, etc. The railway tunnel does not displace harmufly now. We continue measuring on the consutruction and feed back the result of measurement to construction.

View full abstract

This will be the construction of making the two-lane highway road of the tunnel wider, which have been built for 32 years. They will demolish the existing one by the 3.8t large-sized breaker and will reconstruct to make it two-lane highwayroad of the tunnel in the current way. Before excavation, they will have grouting to reinforce the weak rock around the tunnel. And also they are going to recycle all the industrial wastes which they will produce a lot while reconstructing.

View full abstract

Shin-Sakuramachi Tunnel, 1.972km long road tunnel, is part of the 3.54km long renovation section of the national highway No.291, which connects Ojiya-shi and Oguni-cho in Niigata Prefecture. The tunnel passes through an old gas field and the emission of flammable gas was expected before starting work.
This paper describes the safety measure for methane gas emission during tunnel excavation based on the authors' observation of the relationship between atmospheric pressure and the amount of gas emission.

View full abstract

Safer tunneling can be achieved by performing the appropriate measures required for ground stability, observing tunnel face situations and grasping geological conditions precisely in parallel with excavating. We developed the new “Tunnel Face Observation Record System” contributing to efficient tunnelling and highly information-orientd tunnelling. In the system, filming tunnel face with a video camera or a digital still camera, the digital information is transmitted with the SS radio to a site office. The digital information is converted into a list of face observing record with a personal computer. In this paper, we report about the abstract of “Tunnel Face Observation Record System” and the results of radio transmission experiment on reliability of radio telecommunications.

View full abstract

We make study of a method to forecast risk of collapse of the excavated tunnel face. To measure a tunnel face displacement, a laser displacement gauge was used. Several measurement were performed and obtained data were analyzed. As the results of data analysis, it was found that the displacement behaviors were something like creep failure of the rook as obtained from laboratory tests. It was also ascertained that the time of causing such collapse could be forecasted from changing rate of displacement.

View full abstract

Tunnel face observation system is developed and is applied to a construction site. The system is reduced operation time to examine tunnel face observation and to draw geological image of tunnel face. The system is developed in a personal computer. Hardware consists of a personal computer, a image scanner and a color printer. The system consists of two programs. One is that to draw a sketch of tunnel face, maps of geological image and a tunnel geological longitudinal section, which is made by Visual Basic. The other is that to prepare a daily documentation of tunnel face and to output this documentation, which is made by Microsoft Access.

View full abstract

One of methods to evaluate stability of ground around tunnel is observation of qualitative character of its cutting face in under-construction, but evaluation for the method may be varied by the observer, so it is hard to design suitably at present. Therefore, we performed in-situ test by simple tester (ex. seismic prospecting at cutting face) to examine whether the tester, which can represent quantitative character of the ground, can use as index to evaluate the ground. And we examined the relation between the observation record of cutting face and its stability or ground deformation, and studied which items is useful to evaluate the ground.

View full abstract

In the large rock cavern excavation, it is very important for evaluating the stability of the side wall to measure not only horizontal direction displacement but also vertical direction displacement. We developed the device which measure the vertical direction relative displacement in the horizontal borehole to study the rock mass behavior in the vertical direction. In this report, the principle of the device, the accuracy of measurement and application case to a field are described.

View full abstract

In the shield tunnel for the underground river, it makes large tension on the main lings and joints. In this situation, we have been developing “composite segment with new mechanical joint system (NM segment)”. In this paper, we show the mixing ratio of the high performance concrete and the method of primary lining with it in the NM segment, it shouldn't need big plants for lining.

View full abstract

In the shield tunnel for the artificial underground river, inner pressure in addition to both earth and water pressure results in the large tension in the main lining members and the joints.“Anew composite segment with new mechanical joint system” was developed as the primary lining member (segment) suitable for the erection of shield tunnel for the artificial underground river.
In this paper, 3-dimensional F.E.M. analysis, tension tests of the joint models and bending tests of full size joints are performed as the basic research of the joint between two segments.The result of the mechanical behavior of the joint are reported in comparison with the proposed design model.

View full abstract

This developed segment for shield driven tunnel lining has curved unevenness prominence around joint, called “Key Lock”. It is able to disperse and reduce the concrete stress near the bolts effectively. On the occasion of the development of this segment, the basic shape and the effect of “Key Lock” were conducted by the contact FEM analysis, and the efficiency of this joint confirmed by basic experiments. Consequently, these conclusions were gotten;this segment has a superior distinction of shear strength, and the calculation of this segment agrees with the results of analysis using the beam-spring model.These results make us to use this segment at the construction of shield driven tunnel in Malysia.

View full abstract

In this paper, we discuss lining design method of the shield tunnel including secondary lining. In particular, we consider of the transmitted force to segment lining by the weight of the secondary lining, using beam-spring design model. Because the secondary lining in our discussion has been combined with segment lining by means of JIBEL reinforcing bar. Therefore, we estimate local bond-slip relation between JIBEL and secondary lining concrete at the non-linear spring in our analitical model.
Finally, we show that stress and deformation of segment lining due to secondary lining construction has been trend to increase, and dead load stress of secondary lining has been generate tension axial-force at crown of the tunnel.

View full abstract

This paper refers to the underpinning work, which includes two different methods on supporting the existing subway. They are called the URT beam method and PC one adopted according to the subway structure system respectively within about 260 m length of this construction site. This paper firstly in the supporting procedure related to each method, and the monitoring system. Afterwards it shows the result of the comparison between the predicted performance of the subway structure and the measured data, in which both are in the good agreement.

View full abstract