Creep Test Of Sliding Zone Soil And Long-term Stability Numerical Analysis Of Xiapa Landslide

As a common type of landslide,the deformation of ancient landslide has obvious time effect.Sliding zone is a relatively weak zone in landslide.There exists the typical creep phenomenon for sliding zone soils,which affects or even directly determines the long-term deformation and stability of landslide.The determination of model parameters and the method of long-term stability analysis are the key factors affecting the reasonability of the numerical simulation results.Therefore,based on laboratory test and numerical simulation,it is of theoretical value and engineering significance to carry out the analyses of the creep law,model parameters and long-term stability of the landslide.In this paper,the creep properties of Xiapa landslide zone soils are studied by triaxial creep tests.An empirical creep model is put forward,and the sensitivity of the parameters was analyzed.The numerical simulation without considering and considering the creep of the sliding zone is carried out to analyze the long-term deformation and stability of the landslide.The main contents and conclusions are as follows:（1）The triaxial creep tests of sliding zone soils were carried out under the confining pressures ofσ₃=100、200、300 and 400k Pa and stress levels of s=0.30,0.45,0.60 and 0.75.The stress-strain-time relationship of the sliding zone soil is obtained.Test results show that the sliding zone soil has typical creep characteristics.With the development of time,the axial deformation goes through the transient deformation stage,the decay creep stage and finally reaches the uniform creep stage.The axial deformation of sliding zone soil increases with the increase of stress level and confining pressure.The empirical creep model was presented,the strain–time and stain–stress behaviors being expressed by the power and exponential functions,respectively.The creep test results can be expressed well by the empirical creep model.（2）The Burgers model parameters are obtained by the direct method and the least squares based on the laboratory test data.The feasibility of applying the parameters to Burgers-Mohr model is verified by numerical simulation,and the sensitivity of model parameters is analyzed.The results of numerical simulation verify the feasibility of this method.The effect of parameters of Burgers model on axial strain is studied.The results show that the Maxwell shear modulus G_Mand Kelvin shear modulus G_K have a great effect on axial strain.The larger the G_M and G_K are,the smaller the axial strain is.The Maxwell viscosity coefficientη_M and Kelvin viscosity coefficientη_K have little effect on the axial strain in the range of 0.5～2 times of the reference value.The main influence parameter on the axial strain at the steady creep stage isη_M.（3）Based on the Burgers-Mohr creep model,the creep deformation of Xiapa landslide was simulated for one year,and the influence of the creep in sliding zone on the long-term deformation and stability of the slope was studied.The results show that the displacement-time curve of each monitoring point accords with the general creep law,and mainly experiences two stages of decay creep and uniform creep.The displacement of each monitoring point increases rapidly in the first 7 days,and then the growth rate gradually slows down.The distribution of stress field changed little with time.（4）The strength reduction command flow for Flac3D6.0 is developed.The safety factors of the slope are 1.18 and 1.06 respectively when the creep of the sliding zone is not taken into account and when the creep of the sliding zone is taken into account.