Study On Post-buckling Behavior And Its Stability For Side Slope With Bedding Rock Mass

There exists a lot of layered slope rock mass in the southwest mountainous area of China.The geological disasters caused by the instability mainly include the whole buckling failure of the slope in the early stage and the shear failure of the slope toe in the later stage.In this paper,according to the occurrence and buckling deformation characteristics of layered slope rock mass,the initial post buckling theory is applied to study the buckling and post buckling behavior of rock mass structure in different deformation stages,and the stability criteria and buckling failure criteria of slope rock mass in elastic stage,plastic stage and damage stage are established.The main research contents of this paper are as follows:1.Applying the initial post-buckling theory and catastrophe theory,taking the sufficiently small neighborhood near the bifurcation point of the rock structure as the research object,the critical buckling equation and bifurcation buckling equation of the rock mass at the elastic stage are given.The Upper and lower limits of slope rock mass buckling under different displacement boundary conditions;the differential relationship between the modal amplitude of the rock structure near the bifurcation point and its independent related parameters is given,and the post-buckling of the slope rock mass is determined Extreme points on the path.2.Based on the plastic yielding conditions of the rock mass material and the plastic mechanism of the rock mass structure,the elastic initial post-buckling theory is extended to the elastic-plastic initial post-buckling of the rock mass structure,and the initial plastic buckling of the rock mass of the slope is given.The stability value of ultimate plastic buckling is determines when the rock mass structure does not show unloading and neutral loading.3.Based on the damage weakening characteristics of the heterogeneous rock mass,a physical model of the weakening inflection point of the rock mass damage modulus is the value of the residual rock modulus.The residual strength of the rock mass is determined by the asymptote of the Weibull distribution curve.It is pointed out that the residual damage modulus and damage factor under the limit state can be used as universal physical self-similar constants for brittle materials with softening characteristics.4.The damage residual modulus of the bearing rock mass is correlated with the critical buckling point and bifurcation buckling point of the layered rock mass,and the critical damage buckling equation and bifurcation of the rock mass under damage are given.The damage buckling equation points out the applicable conditions and scope of the damage bifurcation equation,and determines the extreme point on the post-buckling path of the slope rock mass under the damage buckling failure state.The results show that the critical buckling load and bifurcated buckling load of the structure are determined by the load defect characteristics of the slope rock mass,the separated buckling of the structure is determined by the critical load of the slope rock mass,the bifurcated buckling of the slope rock mass is determined by the bifurcated load,and the buckling failure of the rock mass structure is determined by the extreme point on the post buckling path;The initial plastic buckling is related to the yield strength of rock mass material.The ultimate plastic buckling depends on the loading characteristics of the slope structure section.After the plastic buckling,the initial load slightly increases is the stable equilibrium,and after reaching the extreme point,the load decreases,and becomes the unstable equilibrium;The inflection point of damage weakening of slope rock mass is only related to the shape parameter of rock mass.The self similar constant of rock mass is determined by the limit value of its shape parameter.When describing the brittle failure behavior of rock mass,the reasonable value of distributed shape parameter is 6.According to the stability behavior and stability criterion of layered slope rock mass,the paper also gives the calculation and analysis of engineering example of bawangshan slope in the lower reaches of Yalong River.