Near The Fault Stress Distribution Of Abnormalities And The Impact On The Stability Of Surrounding Rock Of Underground Works,

This paper study on abnormal distribution of stress and displacement adjacent to fault as well as how stress field of tunnel surrounding rocks and it's stability are influented by fault.According to systematic numerical simulation test,it researches the influences on four primary factors of fault thickness,fault dip,fault deformation modulus and rock stress side pressure coefficient.Using test design method of orthogonal and uniform,applying analysis method of finite difference method,analysising 16 kinds of caculated conditions,and caculating more than 300 kinds of different examples,to get regular results.At last,as tunnel approaches fault,analysises elastic and elastic-plastic changes of surrounding rocks stability state.And possibilities of brittle fracturea on surrounding rocks are typically analysised and compared.Main conclusions as followings:1.At calculating of quasi-3D,only consider the effects of fault unitary structral surface,distribtions adjacent to a fault of principal stress difference on a fault end rapidly from maxcimum to stable state.And distribtions adjacent to a fault of principal stress difference on middle position of a fault also have large reduce,but at the position that far away from the fault will again occur jumping of stress. Finally,it makes stress nearby total fault occur "flow around" phenomenon,and forms special distribution pattern that is stress concentration area of diamond.This is a new discovery.2.Because the difference of initial ground stress on distribution feature,at the special condition leads to shear stress values of conculated results of some fault dip are the minimum dimerize other fault dips(for example:S₁=75°).3.At the position of tunnel Top arch and tunnel side wall,the distribution state of principal stress difference at the special locations also due to stress concentration area of diamond appears sudden increase's phenomenon of principal stress difference.Thus increase the danger of happening rock burst or other rock instabilities.But beacause the different combinations of initial ground stress and fault dips,morphology appearing at the diamond anomaly area will occur changes.4.Using brittle splitting criterion on cave surrounding rock adjacent to a fault to analyze splitting criterion,it's result shows that splitting distribution area is related with the characteristics of principal stress difference,and also is effected by the "flow around" phenomenon.The result of elasto-plastic analysis proves that the effects of fault on the distribution of tunnel surrounding rock mass plastic zone also are significant.