• Title/Summary/Keyword: tunnel theory

Search Result 219, Processing Time 0.021 seconds

Analysis of Tunnel Behavior Using Progressive Rockmass Failure Technique (암반의 진행성 파괴 기법을 이용한 터널거동 분석)

  • 이성민;이윤규;신성렬
    • Tunnel and Underground Space
    • /
    • v.9 no.4
    • /
    • pp.288-295
    • /
    • 1999
  • Concentrated stresses due to the underground tunnel excavation easily cause many problems such as yielding, popping, and failure at the immediate roof, wall and floor of tunnel. Therefore, it is very important to predict the possibility of these problems when a tunnel is excavated underground. There are two typical methods to predict these problems. The one is to predict problems from the analysis of field monitoring data and the other is to predict them from computer simulations using good site investment data. Using the second method, this study attempted to describe the time-dependent or progressive manner of immediate roof and wall due to the underground tunnel excavation. An iterative technique was used to represent progressive failure of rockmass with the Hoek and Brown theory. By developing and simulating three different shapes of twin tunnels, this research estimated the proper size of critical pillar width between tunnels, distributed stresses on the tunnel walls, and convergences of tunnel crowns. Moreover, results out of progressive failure technique based on the Hoek and Brown theory were compared with the results out of Mohr-Coulomb theory.

  • PDF

Roof failure of shallow tunnel based on simplified stochastic medium theory

  • Huang, Xiaolin;Zhou, Zhigang;Yang, X.L.
    • Geomechanics and Engineering
    • /
    • v.14 no.6
    • /
    • pp.571-580
    • /
    • 2018
  • The failure mechanism of tunnel roof is investigated with upper bound theorem of limit analysis. The stochastic settlement and nonlinear failure criterion are considered in the present analysis. For the collapse of tunnel roof, the surface settlement is estimated by the simplified stochastic medium theory. The failure curve expressions of collapse blocks in homogeneous and in layered soils are derived, and the effects of material parameters on the potential range of failure mechanisms are discussed. The results show that the material parameters of initial cohesion, nonlinear coefficient and unit weight have significant influences on the potential range of collapse block in homogeneous media. The proportion of collapse block increases as the initial cohesion increases, while decreases as the nonlinear coefficient and the unit weight increase. The ground surface settlement increases with the tunnel radius increasing, while the possible collapse proportion decreases with increase of the tunnel radius. In layered stratum, the study is investigated to analyze the effects of material parameters of different layered media on the proportion of possible collapse block.

A Study on Fuzzy Logic Method for the Assessment of Tunnel Concrete Lining (터널 콘크리트 라이닝의 상태평가를 위한 퍼지추론기법 연구)

  • 이성원;조만섭;이광호;이석원;배규진;안영기
    • Tunnel and Underground Space
    • /
    • v.9 no.4
    • /
    • pp.337-349
    • /
    • 1999
  • There are many difficulties to the engineers in the assessment of tunnel safety. Consequently, objective assessment of concrete lining is hard even by the experts of tunnel assessment. Of several difficulties in the assessment of tunnel safety, in this study, tunnel concrete lining was focussed iud evaluated quantitatively and objectively using the Fuzzy theory which it generally considered to be appropriate for the assessment, control and judgment. T-FLAS based on fuzzy theory was developed in this study for the quantitative and objective assessment of the concrete lining in tunnels. Based on the application of T-FLAS on the evaluated field data, it was shown that the assessment system using fuzzy theory(T-FLAS) can be the effective and objective method for the assessment of concrete lining.

  • PDF

Numerical Analysis of Tunnel Lining under Loosening Load (수치해석을 통한 이완하중에 따른 터널 라이닝의 거동 분석)

  • Park, Jung-Jin;Kim, Yong-Min;Hwang, Taik-Jean;Jeong, Sang-Seom
    • Journal of the Korean Geotechnical Society
    • /
    • v.27 no.7
    • /
    • pp.35-45
    • /
    • 2011
  • Cost effective design and construction are necessary to establish the design concept of tunnel lining. Loosening load acting on the concrete lining is compared with Terzaghi tunnel theory and numerical analysis. It is analyzed under the condition of weathered rock and soil with varying in-situ stress ratio ($K_0$). Based on the result, loosening load calculated by Tcrzaghi tunnel theory is much greater than numerical analysis results. And the load calculated in weathered soil is lager than weathered rock condition. As in-situ stress ratio increases, the stress acting on the tunnel lining decreases in Terzaghi theory rapidly, whereas there is little effect in numerical analysis.

Development of Countermeasure Expert System for Tunneling Failure (터널 붕락특성과 시공 중 보강공법 선정방법 개발)

  • 김창용;박치현;배규진;홍성완;오명렬
    • Tunnel and Underground Space
    • /
    • v.10 no.3
    • /
    • pp.418-429
    • /
    • 2000
  • Many Studies of tunnel and tunnelling safety have been developed continuously based on the increasing social interests in underground space since 1990's in Korea. Because the growth of population in metropolitan has been accelerated at a faster pace than the development of the cities, underground facilities have been created as a great extent in view of less land space available. In this study, a lot of types of tunnel failure were surveyed and the detail causes were studied after many cases of tunnel failure were collected. There were suggested brief countermeasure of tunnel failure through case study. An expert system was developed to predict the safety of tunnel and choose proper tunnel reinforcement system using fuzzy quantification theory and fuzzy inference rule based on tunnel information database. The comparison result between the predicted reinforcement system level and measured ones was very similar. In-situ data were obtained in three tunnel sites including subway tunnel under Han river. This system will be very helpful to make the most of in-situ data and suggest proper applicability of tunnel reinforcement system developing more resonable tunnel support method from dependance of some experienced experts for the absent of guide.

  • PDF

Development of Countermeasure Expert System for Tunneling Failure (터널 붕락특성과 시공 중 보강공법 선정방법 개발)

  • 김창용;박치현;배규진;홍성완;오명렬
    • Proceedings of the Korean Society for Rock Mechanics Conference
    • /
    • 2000.09a
    • /
    • pp.171-181
    • /
    • 2000
  • Many Studies of tunnel and tunnelling safety have been developed continuously based on the increasing social interests in underground space since 1990's in Korea. Because the growth of population in metropolitan has been accelerated at a faster pace than the development of the cities, underground facilities have been created as a great extent in view of less land space available. In this study, a lot of types of tunnel failure were surveyed and the detail causes were studied after many cases of tunnel failure were collected. There were suggested brief countermeasure of tunnel failure through case study. An expert system was developed to predict the safety of tunnel and choose proper tunnel reinforcement system using fuzzy quantification theory and fuzzy inference rule based on tunnel information database. The comparison result between the predicted reinforcement system level and measured ones was very similar. In-situ data were obtained in three tunnel sites including subway tunnel under Han river. This system will be very helpful to make the most of in-situ data and suggest proper applicability of tunnel reinforcement system developing more resonable tunnel support method from dependance of some experienced experts for the absent of guide.

  • PDF

Study on the stability of tunnel and rock mass classification in Danyang limestone quarry (단양 석회석 광산터널의 암반 평가 및 안정성 연구)

  • ;Choon Sunwoo;Kong Chang Han;yeon-jun Park
    • Tunnel and Underground Space
    • /
    • v.6 no.2
    • /
    • pp.131-143
    • /
    • 1996
  • In-situ survey and laboratory rock test were carried out for rating rock mass around the tunnel that some failures had been occurred in Danyang limestone quarry. For rating rock mass, several methods such as RMR, Q-system, rock strength etc. were applied. The stability analysis on tunnel was evaluated by numerical method FLAC. And The block theory using streographic projection was also applied for stability analysis. The 3-4 major discontinuity sets are distributed in rock mass around tunnel.

  • PDF

Study on tunnel geometry protecting a propeller using potential based panel method (포텐셜 기저 패널법에 의한 프로펠러 보호터널의 형상변화에 관한 연구)

  • Suh, Sung-Bu
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.31 no.5
    • /
    • pp.614-621
    • /
    • 2007
  • The fishing boat propulsion system employing the modified stern shape and the tunnel to protect a propeller is developed to increase the cruise speed and reduce he problem resulting from the open propeller accidentally catching the waste net and able on the sea. Using 3 different tunnel types, the model test was performed in the circular water channel and the panel method based on the potential theory is applied to analyze the open water performance of the propeller. In the numerical analysis using he potential-based panel method, it calculates the hydrodynamic interaction between the propeller and the tunnel and evaluates the effect of the tunnel geometry. From the numerical and experimental results differing tunnel geometries, the propulsion efficiency is increased by the larger diameter of the inlet than the outlet of the tunnel and the smaller gap between the propeller tip and the tunnel internal surface. These results provide the information of the propeller system with the tunnel and the hydrodynamic interaction between the propeller and the tunnel.

Catastrophe analysis of active-passive mechanisms for shallow tunnels with settlement

  • Yang, X.L.;Wang, H.Y.
    • Geomechanics and Engineering
    • /
    • v.15 no.1
    • /
    • pp.621-630
    • /
    • 2018
  • In the note a comprehensive and optimal passive-active mode for describing the limit failure of circular shallow tunnel with settlement is put forward to predict the catastrophic stability during the geotechnical construction. Since the surrounding soil mass around tunnel roof is not homogeneous, with tools of variation calculus, several different curve functions which depict several failure shapes in different soil layers are obtained using virtual work formulae. By making reference to the simple-form of Power-law failure criteria based on numerous experiments, a numerical procedure with consideration of combination of upper bound theorem and stochastic medium theory is applied to the optimal analysis of shallow-buried tunnel failure. With help of functional catastrophe theory, this work presented a more accurate and optimal failure profile compared with previous work. Lastly the note discusses different effects of parameters in new yield rule and soil mechanical coefficients on failure mechanisms. The scope of failure block becomes smaller with increase of the parameter A and the range of failure soil mass tends to decrease with decrease of unit weight of the soil and tunnel radius, which verifies the geomechanics and practical case in engineering.

Grouting effects evaluation of water-rich faults and its engineering application in Qingdao Jiaozhou Bay Subsea Tunnel, China

  • Zhang, Jian;Li, Shucai;Li, Liping;Zhang, Qianqing;Xu, Zhenhao;Wu, Jing;He, Peng
    • Geomechanics and Engineering
    • /
    • v.12 no.1
    • /
    • pp.35-52
    • /
    • 2017
  • In order to evaluate the grouting effects of water-rich fault in tunnels systematically, a feasible and scientific method is introduced based on the extension theory. First, eight main influencing factors are chosen as evaluation indexes by analyzing the changes of permeability, mechanical properties and deformation of surrounding rocks. The model of evaluating grouting effects based on the extension theory is established following this. According to four quality grades of grouting effects, normalization of evaluation indexes is carried out, aiming to meet the requirement of extension theory on data format. The index weight is allocated by adopting the entropy method. Finally, the model is applied to the grouting effects evaluation in water-rich fault F4-4 of Qingdao Jiaozhou Bay Subsea Tunnel, China. The evaluation results are in good agreement with the test results on the site, which shows that the evaluation model is feasible in this field, providing a powerful tool for systematically evaluating the grouting effects of water-rich fault in tunnels.