| The landslide instability induced by seismic conditions is a gradual failure process and its failure mechanism is very complex.Seismic slope stability analysis under the condition of existing research results,ignoring the strongly weathered layer of gravel soil dynamic properties of the impact on the stability,and the earthquake as statics problem under the condition of slope,the implicit finite element method or the pseudo-static method solving the safety coefficient,unable to effectively analyze the seismic landslide stability and in the process of gradual failure process;Or the discrete element method is used to get the progressive failure process of landslide,but this method can not solve the safety factor,so it is difficult to evaluate the stability of landslide under earthquake conditions.At present,there is a lack of a method which can simultaneously calculate the landslide safety factor and progressive failure process under seismic conditions.So in this paper,considering the mountains strong weathering rock,on the basis of soil dynamics characteristics,combined with the dynamic explicit finite element large deformation analysis method,to carry out the earthquake conditions down the mountain area of strongly weathered layer landslide stability research,put forward in the process of earthquake strong weathering landslide stability analysis method of deep overburden,the seismic effect on strong weathering of landslide stability of deep overburden evaluation model,The progressive failure process and threat range of landslide under earthquake condition are given.Taking beishan landslide in Lijie Town,Zhouqu County,Gansu Province as the research background,the stability of landslide of strongly weathered overburden in down-mountain area under seismic conditions is systematically analyzed in this paper.The main research results are as follows:1、The earthquake-induced instability of strongly weathered and deep overburden slopes in mountainous areas is calculated and analyzed as a dynamic large deformation problem.An explicit large deformation numerical analysis method suitable for earthquake conditions affecting slope stability is proposed.Based on the research results at home and abroad,the research status,development level and corresponding deficiencies of the slope stability of strongly weathered overburden in mountainous areas under earthquake conditions are expounded.2、Based on the existing theory,a dynamic viscoelastic-plastic constitutive model of strongly weathered gravel soil is established.The damper and spring are connected in parallel to form the viscoelastic part of the dynamic constitutive model of gravel-soil.The Mohr-Coulomb strength theory is used in the plastic stage of the constitutive model,which is connected in series with the viscoelastic part to jointly establish the strongly weathered gravel.Dynamic viscoelasticplastic constitutive model of soil.The algorithm is realized by the VUMAT subroutine interface of ABAQUS finite element simulation software.The results of stress-strain predicted by this model are compared with the results of dynamic triaxial test in laboratory,and the rationality of the proposed model is verified.3、The static and dynamic parameters of the highly altered residual soil sheet were obtained by drilling soil samples at the engineering site for routine laboratory testing and dynamic triaxial testing.The dynamic modular offset and soil moisture coefficient at different limit pressures and dry densities are described in comparative experiments,and the influence of the initial shear load on the dynamic behavior of the soil is indicated.Using the dynamic constitutive model of residual soil established in this paper,combined with the explicit large deformation finite element method,through the ideal two-dimensional numerical simulation of the slope,the explicit finite element method under explicit conditions is used to calculate the static slope safety factor,and the implicit finite element method and the explicit finite difference method are used to verify the safety factor.The results show that the proposed explicit finite element method can still calculate the safety factor under seismic conditions and that it has the same accuracy as existing methods.4、The stability analysis method of explicit finite element slope with large deformation is applied to study the stability of landslide with strong weathering and deep overburden under seismic conditions.Taking the Beishan landslide in Lijie Town,Zhouqu,Gansu Province as the engineering background,combined with the engineering site geology,topography survey report data and the rock and soil physical and mechanical test data obtained in this paper,the static and dynamic parameters of the rock and soil mass were determined.Two-dimensional model is established according to the engineering field section,using strength subtraction and explicit finite yuanta deformation calculation program is compiled in order to calculate the safety coefficient of slope under the condition of static and earthquake,and comparing the calculation results with Geo-studio software validation,two kinds of software calculation result is very close,proves the rationality of the method in this paper.The gradual failure process of the slope in the sliding process is calculated,the curves of displacement and velocity change with time are obtained,and the maximum displacement of each area of the landslide is given.According to the point cloud obtained from the field survey data,a 3D model of the slope was established by Rhino modeling software,and the safety factor of the slope under static and seismic conditions was calculated by using the explicit large deformation method,and the progressive failure process and influence range of the slope after sliding failure were given.Combined with the site investigation and calculation report,the actual and final threat range of landslide is obtained,which provides a basis for the construction of landslide disaster prevention and control project. |
PDF Full Text Request