Parameter Analysis Based On Random Fractured Rock Slope Stability

The stability of a rock slope is of special importance in geotechnicalengineering. Yet there is no fully satisfactory method to analysis the rock slopestability, especially when the fractures which are randomly distributed in the rockmass are taken into account. The existing slope stability analysis software could notsimulate randomly distributed network for fractures in rock mass. According toMonte Carlo method, this thesis expands the function of the discrete elementprogram UDEC in simulating the randomly distributed network for fractures, andimproves the calculation method for the factor of safety for rock slopes. Parametricstudies have been carried out in this thesis to study the influences on the safety offactor for rock slope for several influencing factors, including the geometricalparameter of the rock joints (number of joint set, density, inclination angle, tracelength), the unit weight of rock, the height and the angle of the slope. Based on thestudies performed in this thesis, the following conclusions have been reached.(1) Based on Monte Carlo method, by using FISH language, randomlydistributed fracture network simulation program in the discrete element programUDEC is coded, to make it capable of generating fracture network.(2) According to the strength reduction principle, by using FISH language, thestrength reduction program is coded. Often in standard UDEC, the number of stepsis insufficient to get the safety of factor for a rock slope, and the calculation time istoo long. In this thesis, the above mentioned two problems are also solved for therandomly distributed joint network.(3) Compared with the classic slope stability analysis example in the existingliterature, the method for calculating the factor of safety of slope based on theprinciple of strength reduction with UDEC is verified, the influences for someinfluencing factors on numerical modeling accuracy are analyzed.(4) Based on orthogonal experiment and the complementary experiment， theinfluences of various influencing factors on the slope stability are analyzed. Someconclusions are reached. For the number of joint set, the factor of safety decreasesas the number of joint set increases, when the number of joint set is equal or lessthan3. The factor of safety for the rock slope decreases as the density of joint, thetrace length of joint, rock unit weight and slope height increase. the factor of safetyfor the rock slope decreases as the angle of the slope gradually increases. Thereduction amplitude of factor of safety gradually slows down as the angle of the rock slope increases to a certain degree. The factor of safety for a rock slopeincreases as the cohesion of the joint graduate increases. Similar to the effects of theangle of the rock slope on the factor of safety, the increasing amplitude for thefactor safety due to the effects of the cohesion also slows down as the cohesion ofthe joint increases to a certain degree. the influence of joint inclination angle toslope stability are related to the slop angle, The more joint inclination angle closesto the slope angle, the smaller the reduction amplitude is. The influence of jointinclination angle variance to the factor of safety of slope does not have an obvioustrend. In addition, based on the analysis on effects of the range, the number ofjoint set, slope height and internal friction angle of fracture have significant effectson factor of safety for a rock slope. The cohesion of the joint, the density of joint,inclination angle and the trace length of joints also have strong impact on factor ofsafety. The angle variance of the joint inclination and rock unit weight has arelatively small impact on factor of safety.