Research On Slope Search For Potential Slip Surface And Stability Analysis Method Under Earthquake

Slope stability under earthquake action has always been a key topic in geotechnical engineering research.In the quantitative analysis of slope stability,the potential slip surface and safety factor are the basis of analytical research,and the evaluation criteria are often the basis of engineering design and decision-making stage.Due to the horizontal inertial force of the seismic load,a large area of tensile damage will occur at the top of the slope.In the past,it was thought that the instability of the slope was only caused by shear failure,and this view will overestimate the stability of the slope.In this paper,the instability of the slope is divided into two parts: tensile failure and shear failure.Based on the discussion of slope state,mathematical function and anti-slip vector,the method of potential slip surface and stability analysis of slope is proposed.The main conclusions are as follows:(1)The definition of the potential slip surface is discussed,and the unit state is used to judge the strength condition of the slope material that forms the potential slip surface.The shear-strain increment and the tensile yielding unit are used to search for the tension-shear slip surface coordinate point of the slope under earthquake action;(2)The mathematical function model of the complete slip surface is constructed,and the Logistic function is selected as the basis function of the slip surface curve.According to the mathematical properties of Logistic,the theoretical methods for determining the parameters are proposed by using the jumping,symmetry of the function and actual engineering precision.(3)According to the failure mechanism of slope under earthquake action,the theoretical points of vector sum method to define safety factor are discussed.Considering the tensile strength of rock and soil,the formula for solving the safety factor is improved,and the calculation formula of tension-shear vector sum safety factor is derived.(4)For the slope stability,the multi-factor sensitivity analysis of the three important strength parameters(cohesion,internal friction angle and tensile strength)in the tensionshear vector sum method was carried out by orthogonal test.In this paper,the overall sliding angle and safety factor are discussed.The sensitivity coefficients of the three strength parameters are: internal friction angle > cohesion > tensile strength,indicating that the internal friction angle is the dominant parameter of slope stability;(5)The time-history analysis of the slope engineering example shows that as the duration of the earthquake increases,the potential slip surface of the slope will move toward the interior of the slope,and the original shallow damage will transform into deep damage;the tension-shear vector sum method obtains the safety factor time-history map to clearly reflect the dynamic change of slope stability.