Study On Failure Criteria For Soil-similar Cutting Slope

The soil-similar cutting slope is one of the primary and important types of cutting slopes at present,its engineering properties are obviously different from the well-known soil slopes or rock slopes,so it's deformation and failure is the most difficult in geotechnical engineering.To resolve the numerous problems about stability analysis etc during the process of constructing expressways,the research on failure criteria of soil-similar cutting slopes was worked out by finite element method ANSYS in this paper based on shear strength reductionve methods.The investigation contents invovle slope type,deformation and failure mode,and its characteristics,the law of development.In view of two common destructive ways of slope,the research contact project examples,based on three main criterias for evaluating instability:the convergence of equation's solution,the abruptness of the displacement or deformation at a certain characteristic,location and the connectivity of plastic zone,in order to determine the safety factor and deformation of slope's failure criteria.The main results and conclusions of the thesis are as follows:(1)The soil-similar cutting slopes have different distructive ways,different types of slope slip surface shear export position has different characteristics;(2)This paper presents the conversion relationship between two different yield criterion.Combine two project examples,compared with three most frequently used yield criterion for the calculation of results,and with the limit equilibrium method. The results show that it's the most appropriate yield criterion to analyse soil-similar cutting slopes with the equal-area circle D-P criterion under the conditions of plane strain and non-associated flow rule(ψ=0).(3)This paper discusses the slope commonly used three criterion(the convergence of equation's solution,location and the connectivity of plastic zone,the abruptness of the displacement at a certain characteristic),propose it's better accuracy to use the largest horizontal displacement or maximum value of plastic strain of the slope as the main criterion,and supported by calculating the convergence criterion and the plastic zone through the criterion for analysis.Finally,the safety factor of instability criterion and deformation instability criterion are obtained in the examples.(4)This paper analyzes the impact factors of such slope instability criterion, obtain:it is not better that it is the greater calculating range,it should be studied in accordance with concrete analysis of concrete problems;The grid spacing should be appropriate,encrypt the part in slipping the range will improve and calculate the time and precision;Cohesion and internal friction angle have the greatest impact in slope stability.The safety factor of the slopes decrease with the cohesion(or internal friction angle) decrease,the critical displacement values of the slopes decrease with the cohesion(or internal friction angle)increase;Elastic modulus and poission's ratio of the impact factor of safety can be neglected,the condition is that the elastic modulus value of rock and soil should not be too small,if small,it's likely to result in part of soil deformation is too large to converge,eventually to have a significant impact on the safety factor;Elastic modulus have a great impact on deformation of slope; Consider the effects of shear angle will enable the calculation results more in line with the actual.And obtained the relational expression between influence factor and failure criteria values through quadratic curve fitting.