The Research On The Effects Of Yield Criterion For Slope Stability Analysis

Slope stability analysis is a basic problem which has theoretical and practicalvalue in the geotechnical engineering and it is also a difficulty and hotspot in today’sacademia and engineering. Traditional slope stability analysis uses the limitequilibrium method which has clear concept and is easy to understand. But limitequilibrium method can only calculate the most dangerous sliding surface of slopeand its safety factor, but cannot get the strain and displacement distribution on slope,and its results are conservative. Through using finite element method to calculateslope stability, we can analyze heterogeneous soil under complex boundary conditionsand loading conditions and obtain the displacement field and stress field. Progressivefailure process of the slope is reflected, the plastic zone of slope is searched at thesame time, the most dangerous surface in failure is found which is more reasonable.There are two important issues in applying finite element method to calculateslope which are the determining of the most dangerous slip surface and the selectionof yield criterion. Using finite element method to analyze slope stability, we use theideal elastic-plastic constitutive model and choose the appropriate yield criterion. Thecalculation accuracy of this method is not satisfying which is caused by improperselection of yield criterion. This paper uses finite element method to analyze theeffects of choosing yield criterion on slope stability analysis. Conclusions are asfollows:1．The finite element method applied, equivalent plastic strain contours wereused to determine the slip crack surfaces of slope. Compared with the traditionalmethod, the analysis results showed that the two methods were consistent.2．This paper selected five kinds of commonly used D-P principles in slopestability analysis and described the derivation of the five yield criterions. Thetransformation of strength parameters among different yield criterion was finishedand their proper implementation in the software of Marc was completed.3．Through the application of finite element method, the stress and straindistribution of the slope, displacement field and slip surface location under differentyield criterion were analyzed. The effects of yield criterion on the analysis resultswere studied and its influence on the calculation accuracy of slope stability safetyfactor was also analyzed. It showed that the outside circle yield criterion analysis and compromise round, in the numerical value and distribution of strain and displacementfield area, the difference is bigger than the other three kinds of yield criterions, whichshould not be commonly used. On the slope stability safety factor value, comparedwith the traditional method, the difference of external circle yield criterion wasaround25%. Such as inscribed circle, inside circle, the difference between the otherthree yield criterions and the traditional methods was about10%.4． Finite element models of reinforced soil slope under different yield criterionswere established to calculate the increasing stability of the slope in reinforcement.The results showed that large value distribution area of strain and displacement wassignificantly decreased after reinforcement. The increments value of slope stabilitysafety coefficient under different yield criterions was around10%.