Study on Numerical Method for Failure Process and Stability Evaluation of Rock Block in Tunnel

CHEN Shijie, XIAO Ming, CHEN Juntao

Abstract

    In order to analyze the failure mode and stability of block under complex surrounding rock,a numerical analysis method for block failure was proposed based on continuum mechanics. Firstly,based on the existing geologic plane modeling method of element reconstruction and node separation method,the grid-based block identification was carried out. Then,the expressions of contact force under various contact states were derived based on the explicit contact force method,and the contact analysis method of block and surrounding rock was proposed. Afterwards,the safety factor of block was calculated based on the strength reduction method. The numerical method can simultaneously calculate the deformation of surrounding rock and the deformation of block. A simple example of a double-plane sliding block also demonstrated that,under certain conditions,the numerical results are consistent with the results of rigid body limit equilibrium method. Finally,combined with a tunnel engineering across a fault,the stability of surrounding rock and blocks was analyzed. The results indicate that the numerical method effectively reflects the influences of stress and deformation form surrounding rock when evaluating the block stability. After failure of the key blocks,the potentially dangerous blocks occur in large deformation and the safety factor is low. This numerical method provides an effective analysis method for the stability evaluation of tunnel blocks under complex geological conditions.

 

 

Keywords:  tunnel,  rock block,  contact force method,  stability analysis,  strength reduction method,  numerical method


Full Text:

PDF


References


BOYLE W J,GOODMAN R E,YOW J LI Field cases using key block theory[C]// Proceedings of the International SymposiumFinland,1986:1183—1199

GOODMAN R E,SHI G H. Block theory and Its application to rock engineering[J]. Prentice-Hall,1985,26(1):103—105.

YU Q,OHNISHI Y,XUE G,et al. A generalized procedure to identify three-dimensional rock blocks around complex excavations[J]. International Journal for Numerical and Analytical Methods in Geomechanics,2009,33(3):355—375.

LIU J,LI Z K,ZHANG Z Y. Stability analysis of block in the surrounding rock mass of a large underground excavation[J]. Tunneling and Underground Space Technology,2004,19(1):35—44.

LIU G,LI X Z,LANG C Y. Dynamic evolution and block stability analysis of surrounding rocks [J]. Rock and Soil Mechanics, 2009,30(6):1741—1746.(In Chinese)

WANG S J, YANG J F,LIU Z H, et al. Stability analysis of underground cavrn [M] . Beijing: Science Press, 1984: 172—180.(In Chinese)

HUANG Z J,WUA Q,SHENG Q. Usage of block theory in the three gorges projects [J]. Chinese Journal of Rock Mechanics and Engineering,2001,20(5):648—652.(In Chinese)

JU N P,ZHAO J J,HUANG R Q,et al. 3D stability analysis on rock slope blocks using 3DEC method[J]. Journal of Liaoning Technical University,2009,28(6):925—928.(In Chinese)

ZHU Y S,ZHU H C,SHI A C,et al. Complicated block stability analysis of Baihetan hydropower station based on distinct element method [J]. Chinese Journal of Rock Mechanics and Engineering, 2011,30(10):2068—2075.(In Chinese)

ZHANG Y T,XIAO M,CHEN J T. A new methodology for block identification and its application in a large scale underground cavern complex [J]. Tunneling and Underground Space Technology, 2010,25(2):168—180.

ZHANG Y T,DING X L,LU B. General method for stability evaluation of rock blocks based on numerical simulation[J]. Chinese Journal of Rock Mechanics and Engineering,2017,36 (1):78—92.(In Chinese)

LIU J B,SHARAN S K,WANG D,et al. A dynamic contact force model for contactable cracks with static and kinetic friction[J]. Computer Methods in Applied Mechanics and Engineering, 1995,123(1):287—298.

ZHAO J,XIAO M,CHEN J T,et al. Explicit dynamic DDA method considering dynamic contact force [J]. Shock and Vibration,2016(1):1—12.

ZHAO J,XIAO M,CHEN J T,et al. Simulation methodology of weak structural planes in large underground chamber based on element reconstruction and node separation[J]. Journal of Hunan University (Natural Sciences),2017,44(3):134—142.(In Chinese)

ZHANG A J,MO H O. Improving displacement mutation criterion of slope failure in strength reduction finite element method [J]. Rock and Soil Mechanics,2013,34(S2):332—337.(In Chinese)

LIU J H,LI Z H. The application of block theory to engineering rock mass stability [M]. Beijing:Water Resources and Electric Power Press,1988:60—80.(In Chinese)


Refbacks

  • There are currently no refbacks.