Stability Analysis On Joint Rock Slope Under Earthquake Action With Numerical Simulation

Disaster survey results of Wenchuan earthquake show that earthquake slumpingmainly developed within thick-bedded or massive rock, in which local intensity isrelatively large and joints are obvious. As one outstanding problem, earthquakeslumping markedly differs from those induced by rainfall and other factors, but it doesnot still obtain enough attention. Meanwhile, numerical analysis methods of finiteelement and finite difference both based on the assumption of continuous media andsmall deformation are used in previous studies of slope stability. There have beensome limitations to study the dynamic analysis of large deformation of rock slope,which has a large number of interfaces of discontinuity.In order to overcome those shortages, the dynamic response of joint rock slopein this thesis is simulated by means of the discrete element numerical simulation,especially deformation characteristics, failure mechanism and influencing factors ofslope stability. Here, taking the rock slope which contains two groups of joints as theresearch object, UDEC is carried out and the actual earthquake records is inputted tosimulate a large number of cases for calculating the permanent displacement of thejointed rock slope under earthquake action. Furthermore, critical factors influencingpermanent displacement of jointed rock slope are respectively explored in differentfactors, i.e. slope height, seismic intensity, slope angle and joints angle. Moreover, forthe example case of jointed rock slope,109Tunnel of the Baoji-Chengdu Railway,the dynamic response and mechanism of fracture is analyzed by means of UDECunder earthquake. The creative results are summarized as follows.(1) In general, intact hard rock slope could not slump under earthquake action.However, the stability of the joint rock slope is controlled by the joint strength and itis reduced with the increase of slope height, slope angel and seismic intensity.(2) The dynamic damage of joint rock slope has relation with the inclination andangel between two joints and the slope is more stable when the angels between two joints are bigger. The cases with inclination angles greater than90°is more stablethan those ones with angle less than90°, and also so do cases of inclination angle ofjoints greater than slope angle or less than15°.(3) The tensile failure is occurred in slope surface and extended from bottom toheadpiece along the slope in the initial earthquake.(4) The tensile failure is gradually developed to inside and the lower part of thetensile failure is gradually expanded and extended to headpiece with the role of theearthquake.(5) At the end of the earthquake, the surface of the jointed rock slope isdestroyed by tensile failure and the whole through regional upper part of the slopeoccur slump destruction when the plastic destroyed areas developed a through area.(6) Take the variation tendency of the displacement/velocity time curve of keypoint to determine the critical state of the jointed rock slope. And the factor of safetyof the slope is computed under earthquake action by using the strength reductiontechnique.