Numerical Simulation Of Progressive Failure Of Soft And Hard Interbedded Anti-dip Rock Slope

Anti-dip slope is a common type of slope in Southwest China,and toppling deformation is the most common form of failure.In recent years,with the development and utilization of water resources in Southwest China,the impact of anti-dip slope on people’s production activities is increasing.During the construction of water conservancy projects,landslide accidents caused by the deformation and instability of anti-dip slopes are also common,which not only bring incalculable economic and property losses to people,but also seriously threaten the life safety of residents downstream of the slope.At the same time,in the engineering example of anti-dip slope toppling deformation,the proportion of anti-dip slope with weak interlayer type is larger.Compared with homogeneous hard rock anti-dip slope,the failure strength of anti-dip slope with weak interlayer type is lower,and the failure form is also different.Therefore,it is very important to study the toppling deformation process and reinforcement method of soft and hard interbedded anti-dip slope.In this paper,a numerical model of soft and hard interbedded anti-dip slope is established by continuous-discrete coupling numerical simulation analysis method.The validity of the numerical model is verified by comparing with the centrifuge physical model test carried out by predecessors.On this basis,the slope failure modes under different centrifugal loads are analyzed,and the slope failure stages are divided according to the change of slope displacement.By changing the shape parameters of different slopes,the influence of different parameters on the failure mode of soft and hard interbedded anti-dip slopes was studied.Through orthogonal test design,the sensitivity of different slope parameters to the failure mode of soft and hard interbedded anti-dip slope is analyzed.Finally,the slope with small failure load and large toppling range is reinforced by bolt,and the influence of anchorage length and anchorage angle on the stability of anti-dip slope is further explored.The optimal anchorage length and optimal anchorage angle are determined by analyzing the change of slope safety factor.The specific work carried out is as follows :(1)Based on FDEM(Finite-Discrete Element Method)method,a numerical model of soft and hard interbedded anti-dip slope is established.The numerical simulation results are compared with the physical model experiments of anti-dip slope carried out by predecessors to verify the effectiveness of the model.According to the deformation and displacement of slope in numerical simulation,combined with the internal stress of slope,the failure process of slope is divided into slope stability stage,crack development stage,toppling deformation stage and failure stability stage.(2)Two slope shape parameters,slope angle and rock dip angle,are selected to analyze the failure characteristics of anti-dip slope.The results show that the failure displacement of slope is linearly positively correlated with rock dip angle and slope angle.The slope failure load is roughly linearly negatively correlated with the slope angle and negatively correlated with the slope angle.The slope failure mode changes from ’ toppling-bending ’ to ’ toppling-breaking-block ’ and ’ toppling-breaking-collapse’ with the increase of rock dip angle and slope angle.The angle between the fracture surface and the layer of the slope has little correlation with the slope angle and the dip angle of the rock layer.The angle between the fracture surface and the slope surface is linearly positively correlated with the slope angle and the dip angle of the rock layer.The results show that the slope angle and the slope height are the two factors that have the greatest influence on the slope failure load.(3)The orthogonal test is designed to study the sensitivity of the slope influencing factors with the slope angle,the dip angle of the rock layer,the slope height,the thickness of the rock layer and the thickness ratio of the soft and hard rock layer as the influencing factors,and the slope displacement,the displacement change of the slope,the failure load and the angle of the fracture surface as the evaluation index.The slope angle has the greatest influence on the slope failure displacement and displacement change rate.The angle of the fracture surface of the slope is only sensitive to the slope angle,and the influence level is small with other influencing factors.(4)Anchor reinforcement model of soft and hard interbedded anti-dip slope is established.Anchor reinforcement analysis of anti-dip slope with small failure load and large toppling range is carried out.The influence of different anchorage length and anchorage angle on the failure load and safety factor of anti-dip slope is studied.On this basis,the optimal anchorage length and anchorage angle of bolt reinforced slope are studied.The results show that the safety factor of the slope increases with the increase of the anchorage length.When the length of the bolt is 8m,the stability of the slope is obviously improved.The safety factor of the slope increases first and then decreases with the increase of the anchorage angle.When the angle between the anchorage angle and the rock stratum is 40°-50°,the bolt has the greatest improvement on the safety factor of the slope.