Reliability Analysis Of Slopes Considering Anisotropy Of Undrained Strength

Under the influence of long-term and complex geological evolution,the parameters of the soil slope show obvious variation characteristics in space,which will have a certain impact on the safety and stability of the slope.However,at this stage,most slope reliability studies that consider the spatial variability of parameters focus on isotropy,and rarely consider the differences in the variability of parameters in various directions.In order to make up for this shortcoming,this paper will,on the basis of the stochastic finite element method,consider the spatial anisotropy of the undrained strength of the three clay slopes with different distribution of the mean undrained strength in the depth direction,and establishment the slope reliability analysis method,which explores the influence of undrained strength anisotropy on slope reliability.The main research contents and results are as follows:(1)This article first briefly introduces the stochastic finite element method.Based on this,the clay slope whose average undrained strength does not change with depth is used as the research object,and a random field that can characterize the anisotropy of undrained strength is established.The analysis is based on the calculation results.According to the calculation results,the influence of undrained strength anisotropy on slope reliability is analyzed.It is found that if the anisotropy is ignored,the actual failure probability of the slope will be underestimated;secondly,the slower the slope,the less the influence of the anisotropy on the reliability of the slope can be ignored.(2)Based on the stochastic finite element method,aiming at the clay slope whose mean undrained strength increases linearly with depth,an undrained strength anisotropic random field is established to calculate the failure probability of the slope under the conditions of different safety factor averages and undrained strength variation coefficients.According to the results,the influence law of undrained strength anisotropy on slope reliability is explored.The analysis of the results found that when the mean value of the safety factor satisfies the design conditions,the failure probability increases with the increase of the anisotropy coefficient;the larger the coefficient of variation,the larger the failure probability increases.(3)Based on the stochastic finite element method and considering the anisotropy of undrained strength,the reliability of two-layer clay slopes with different average undrained strength values of the upper and lower layers is studied.Through analysis,it can be concluded that for a two-layer slope,when the undrained strength is isotropic(the anisotropy coefficient is 1),if the slope failure probability is equal to the upper limit 1,the failure probability decreases slowly with the anisotropy coefficient increasing.In addition,when the slope undrained strength variation coefficient is greater than or equal to 0.4 and the undrained intensity mean ratio continues to increase,the change curve of the failure probability with the increase of the anisotropy coefficient gradually tends to coincide,and at the same time,it shows a continuous increasing trend and the probability of slope instability becomes higher.(4)While the random finite element program is used to calculate the failure probability of three different slopes,the instability failure mode diagram of the slope can also be obtained.Through observation,it is found that the higher the degree of undrained strength anisotropy,the slope sliding surface changes from irregular to curved,and the range of soil sliding also becomes wider,and the damage position changes from shallow to deep,gradually moving toward the bottom of the slope models.