Study On Slope Stability Based On Crack-Damage Model

Slope stability analysis is an important component of disaster prevention and disaster reduction research. Which is also the most difficult and emergent problem needed to be solved in slope construction and design. The strength reduction method (SRM) do not have to make any assumption, it can search for the critical slip plane and find out the minimum safety factor for the slope in an automatic way. It can be used to analyse any slope unconstrained.The strength reduction method (SRM) is a common method in slope stability analysis for the advantages of this method.There are several failure criterions that have been used in the SRM.But a consensus hasn't been got that which criterion is the best one.The fractured rock slope stability is always the emphasis and difficulty for the geotechnical engineering and engineering geology workers. The slope stability with goaf in the conversion process of underground mining and open pit is also an important problem. So the present paper has done the studies to solve these problems. The main contents and conclusions are:The fractured rock is regarded as continuum with damage. With comprehensive consideration of the branch cracks seeding, propagation and damage evolution subjected to compression stress and tension stress,the initial damage tensor and additional damage tensor is used to describe the damage evolution process. The initial damage tensor and the additional damage tensor of fractured rock under compression stress and tension stress is added to the rock flexility tensor. An user defined expanded FLAC3D constitutive model that can be used to anlysis the the damage evolution process of rock is developped with visual C++ programming language.The slope damage-degree distribution is influenced by the fractured slope geometry and slope material properties and the crack features. The maximum of stress intensity factor KImax and damage degree Dma become larger when the slope angleφand height H become larger. The maximum of stress intensity factor KImax become larger when the slope cohesion become larger. The maximum of damage degree Dmax become smaller when the slope cohesion become larger The maximum of stress intensity factor KImax and damage degree Dmax become smaller when the slope friction angleφbecome larger. The maximum of stress intensity factor KImax become larger when the initial crack length become larger. The maximum of damage degree Dmax show decreasing trend in the overall when the initial crack length become larger.Rock deformation and failure is the combined result of energy dissipation and release.The elastic-strain energy and plastic-strain energy computed function is intruduced into Mohr Coulomb criterion on the base of Mohr Coulomb criterion.The FLAC3D user defined constitutive model is developed to compute the deformation energy.The ralationship between the elastic strain energy and plastic strain energy is studied.The variation of accumulated elastic strain energy in the strength reduction process is analysized. The accumulated elastic strain energy will be increased first and then decreased with the increasing of reduction coefficient. The slope lies in limiting equilibrium state at the mutation point. This rule is used as the slope failure criterions to determine slope failure.To anlyse the affect of goaf to slope stability, many slope models are created.The slope stability will be enhanced when the goaf lies in the slope upper.The slope stability will be enhanced when the goaf located in the central of slope lies in the landslide. The slope stability decrease when the goaf located out of the landslide lies in slope central. The slope stability decrease when the goaf lies in the slope bottom.A benchmark point is established to analysize the slope dynamic response.The slope dynamic coefficient is defined.The different slopes with different height under different dynamic loads are analysized.The FISH programe is compiled to recoder the maxmium of the velocity and acceleration and the principal stress. The maximal velocity and principal stress isoline is plotted. The slope dynamic response can be found by these contours.Three monitoring points is established.The horizontal and vertical velocity and acceleration of the monitoring point is recorded. The slope dynamic response is founded through them.The slope damage is also analysized with the recorded maxmium of the principal stress.