Study On Progressive Failure Mechanism And Stability Analysis Method Of Excavated Soil Slope

The instability of the slope is not a one-step failure,but the result of years of gradual destruction.In this paper,the finite element software is used to simulate the process of slope instability.The process of shear zone development and expansion is analyzed from the stress state of shear zone soil element,and the mechanism of progressive failure of slope is revealed.Based on this,the finite element element destruction criterion is proposed to simulate the process of progressive failure of the slope.The deficiencies of the traditional finite element strength reduction method and the displacement mutation criterion are optimized,and a new finite element dynamic strength reduction method is proposed.The single factor sensitivity analysis of slope geometry,physics and model parameters affecting the displacement of slope feature points is carried out.Based on the grey correlation analysis method,the criterion of the normalized deformation of the excavation slope is studied.And its rationality is verified through engineering cases.The main research contents and results of this paper are as follows:(1)By summarizing the law of soil unit failure,the unit failure criterion S is proposed,and based on this,the unit yield criterion S' is proposed.(2)Through the stress analysis of the monitoring unit on the shear band,the mechanism of progressive failure of the slope is revealed.According to the unit failure criterion,the process of development and extension of the shear band is reproduced,and the law of progressive failure of the slope is vividly simulated.(3)In order to optimize the traditional finite element reduction method,the modified Sekiguchi-Ohta model and the mutation criterion of displacement change rate is introduced.On the basis of considering the softening of the shear band strength,the reduction range and method are improved,and the dynamic strength reduction method is proposed.(4)The single factor sensitivity analysis of the slope geometry,physics and model parameters affecting the displacement of the apex of the slope is carried out.On the basis of this,the criterion of the instability of the normalized deformation of the excavated soil slope is summarized by the grey correlation analysis method.And the rationality is verified through engineering cases.