Research On Failure Criterion And Analysis On Stability Of Complex Slope Based On Strength Reduction Method

With the rapid development of social economy and the comprehensive progress of science and technology,the level of infrastructure construction has achieved a comprehensive leap.More and more large-scale projects continue to refresh the new record.In these projects,the number of slopes is increasing,and the height is getting bigger and bigger,while the slope stability problem can not be ignored and even become the key to the success of the entire project construction.In the current slope study,the safety factor is usually used to evaluate whether a slope is stable,which reliability has an important impact on the safety of the slope and the whole project.In the field of slope stability analysis of safety factor calculation,the limit equilibrium method has a long history and a lot of application experience,because of its simple calculation and widely use.However,the limit equilibrium method makes a series of simplifications and assumptions on the slope,which is different from the actual situation of the slope.Especially,it's difficult to get reliable results by using the limit equilibrium method to analyze complex slopes with joints and weak interlayers.Since the 1970s,the strength reduction method,which is more rigorous in the theoretical system,fully satisfies the static permission,strain compatibility and the nonlinear stress-strain relationship of the rock and soil,has been developed rapidly.Instead of dividing the model or making assumption that the shape and position of the sliding surface before the calculation,the strength reduction method gets widely applied.While,the strength reduction method has not yet formed a uniform standard of uniformity in determining the instability criterion(the termination condition of the safety factor calculation process)when the slope reaches the critical instability state.The influence mode and degree are not clear,which restricts the further development and application of the strength reduction method in the engineering field.In this paper,the FLAC3D software is used to analyze the slope stability with Mohr-Coulumb yield criterion.First,based on the plane strain model of a rock slope,considering the simple homogeneous slope,weak sandwich with and without support three different slope conditions,the slope stability and the safety factor of stability is analysed through the limit equilibrium method that combined with the Finite difference strength reduction method.By comparing and discussing the rationality and reliability of each method and criterion,it is considered that the strength reduction method should be used to analyze the slope safety factor regarding to the stability of the complex slope and the complex slope.And the convergence criterion and the characteristic point displacement mutation criterion(taking the small value)shall also take into consideration for calculating the slope safety factor.Furthermore,based on the principle of control variables,the elastic modulus,Poisson's ratio,dilatancy angle,tensile strength of slope rock mass and the c and ? of weak sandwich are discussed respectively.The influence on the combined criterion of convergence criterion and characteristic point displacement mutation criterion of strength reduction method is offered,as well as the accuracy of the parameters in the engineering application.Finally,the stability analysis on the large 3D complex slope,integration of the combined criterion of convergence criterion and characteristic point displacement mutation criterion of strength reduction method,verifies the rationality of the calculation method.