Stability Analysis Of Slope Considering The Influence Of Principal Stress

With the rapid development of transportation infrastructure in northwest China,under the influence of geological environment,climatic characteristics,human factors and other reasons in the region,landslide accidents arc common,which not only cause huge losses to the national economy,hinder social and economic development,but also endanger the lives and property of people in northwest China.As we all know,slopes and landslides have certain differences.Slopes are generally natural and artificial slopes,such as:the boundary of the mining area excavated by open-pit mines,the roadbed slopes in road engineering,the cutting slopes formed by the excavation of cuttings,etc.,and landslides refer to natural slopes in a creeping or sliding state induced by natural factors,as well as large-scale landslides caused by slope excavation that cause the revival of ancient landslides or the aggravation of natural landslides.Taking the Lijie Beishan landslide as the actual engineering background,this paper studies the soil mechanical characteristics of the crushed rock soil samples taken at the site through on-site investigation,indoor experiment,theoretical analysis and numerical simulation,and analyzes the slope deterioration process and failure mode of slope landslide under static and dynamic conditions.Considering the gradual process of slope instability failure,according to the existing theoretical basis of soil dynamics,ABAQUS numerical simulation software was used to study the stability of slope under static dynamic state and the influence of principal stress coefficient on slope stability in static state by using ABAQUS numerical simulation software and displaying finite element dynamic large deformation analysis method.Most of the traditional slope stability analysis methods do not consider the influence of intermediate principal stress on the stability of slope and landslide,and this paper uses the ABAQUS secondary development function to use the dynamic viscoelastic-plastic constitutive model subprogram that introduces the middle principal stress coefficient factor b to change the user-defined parameters to study the influence of the principal stress coefficient on the stability of slope displacement in the static state.The main research results are as follows:1、Based on the existing soil dynamics theory and the theory of unified strength of double shear,a dynamic viscoelastic-plastic constitutive model suitable for the sampling of gravel soil obtained in this paper was constructed.By connecting the damper and the spring in parallel as the viscoelastic part in the dynamic constitutive model,the plastic element is used as the plastic part in the dynamic viscoelastic-plastic constitutive model,and then the two parts are connected in series to form the dynamic viscoelastic-plastic constitutive model in this paper.The Fortran language is used to compile the subprogram,and the algorithm is implemented through the Vumat subprogram interface in the finite element numerical simulation software ABAQUS,and finally the model prediction results are compared with the indoor dynamic triaxial test results to verify the correctness of the proposed method.2、According to the on-site drilling sampling to carry out indoor routine test and dynamic triaxial test,the static and dynamic parameters of soil samples are obtained,and basic material data are provided for numerical calculation.The ideal two-dimensional slope model is established,and the dynamic viscoelastic-plastic constitutive model of crushed rock soil is combined with the finite element calculation method of displaying large deformation to solve the safety factor of the ideal two-dimensional slope,and the obtained results are compared with the results of the finite difference and implicit finite element calculation,which verifies the reliability and correctness of the display finite element calculation method used in this paper to calculate the safety factor of the slope.3、When analyzing the stability of slopes using the strength reduction method,the commonly used Mohr-Coulomb criterion does not consider the influence of intermediate principal stress on the strength of geotechnical materials,so that the calculation of stability coefficient is biased towards safety,and does not give full play to the strength reserve of slope soil.By modifying the user-defined parameters,the static and dynamic conditions of the homogeneous slope were simulated under the five values of b=0,b=0.25,b=0.5,b=0.75 and b=1.0,and FLAC 3D and ABAQUS numerical software were used to compare and analyze the static state,and the influence of the principal stress coefficient b value on the stability of the slope was considered under different flow rules.Similarly,the stability analysis of the landslide in the north mountain of Lijie was carried out under the condition that the mechanical parameters of soil materials were consistent,and with the increase of the B value of the principal stress coefficient,the displacement of the slope showed a decreasing trend,and the safety factor of the slope showed an increasing trend.4、The proposed stability analysis method showing finite element large deformation slope is used to study the stability of the slope in the static and dynamic state.A homogeneous two-dimensional slope model is established,and the strength reduction method is used to calculate the safety factor under static and dynamic conditions,and it is compared with the calculation results of FLAC 3D and Geo-studio numerical software,and the calculation shows that the maximum difference between the results obtained with the other two methods is less than 2%,which confirms the rationality of the proposed method.According to the calculation results of two-dimensional homogeneous slope in static and dynamic states,the corresponding slope velocity and slope displacement curves are obtained,and the results show that the landslide has a farther sliding distance and is more destructive in the dynamic state.Finally,by taking Lijie Beishan as the actual engineering background,according to the project site survey mountain profile and field monitoring of elevation points,a two-dimensional landslide and a three-dimensional landslide model of the mountain profile are established,and the static and dynamic calculations are carried out by the calculation method in this paper,and the gradual failure process and failure mode of the two-dimensional three-dimensional landslide are analyzed.The sliding distance and threat range of slope damage are given,which provides an effective basis for landslide protection and disaster prevention.