Large Deformation Finite Element Analysis On The Stability And The Failure Mode Of Soil Slope

The stability analysis of soil slope is one of the important subjects of disaster prevention in Hydraulic engineering.As an effective analysis method,the finite element（FE）method can reasonably distinguish the stability and predict the safety factor of slope.Now the analysis of slope stability generally adopts the small deformation finite element method,and the safety factor of slope is calculated by Strength Reduction Method.However,the failure criterion of slope controversially and the error caused by the non-convergence of finite element analysis of small deformation are still the problems.In addition,there are few studies on the empirical formula of slope safety factor and the discriminant method of slope failure mode.Based on this,some studies are carried out as bellow:（1）Analysis of slope stability based on large deformation FE methodFor the stability analysis of slope,an analytical model of soil slope is established based on coupled Eulerian-Lagrangian（CEL）method.The effects of mesh size,step time,Young’s Modulus,Poisson’s ratio and initial geostatic stress on the calculating results were quantified.By comparing with the published numerical results,the effectiveness of the CEL model was verified.（2）Calculation of slope safety factor with new criterionThe applicability of energy mutation criterion and plastic zone coalescence criterion in CEL method is discussed.It is suggested to adopt energy mutation criterion in CEL method through comparative analysis with different criteria.For the plastic failure zone criterion,the critical cumulative plastic strain（P_c）was proposed,which quantifies the determination of safety factor.（3）An empirical formula for calculating the safety factor is proposedThe influences of friction angle,cohesion,soil mass density,slope height and slope angle are investigated,and the influences and the trend of increase or decrease are analyzed.The results were divided into 15°～60°and 60°～75°according to the slope angle.The validity of the empirical formulas was verified by the supplemental calculated results and the numerical results of other researchers,and the maximum error was controlled at about 10%.（4）Studying the discrimination method of slope failure modeThe influences of friction angle,cohesion,soil mass density,slope height and slope angle on the location of failure surface,the range of plastic penetration zone and the equivalent plastic strain are investigated.The critical failure parameters λ₁ and λ₂ are defined to distinguish shallow failure,middle failure and deep failure.The critical failure parameters of the slope with different slope angles were calculated,and it was found that the critical failure parameters and tangent values of slope angles were approximately linear.The results were fitted,and the empirical formulas for calculating the critical failure parameters λ₁ and λ₂were established.