Numerical Simulation On Toppling Deformation And Failure Mechanism Of Steep Bedding Rock Slope

According to the angle's relation of stratum and slope, the stratified rock slope can be divided into four parts: horizontal,transverse, reversal incline and bedding slope. Among these, the bedding slope is most likely to slide.Along with the development of the construction,the bedding rock slope problem is more extrude.The bedding rock slope'instabllity is the most familiar problem in rock slope engineering.Generally speaking,it is believed that slip-rupture and slip-bending are main characteristics of deformation and failure of bedding rock slope.However,based on the collection of systemic references and plenty of situ surveys,it is found that there is another particular form of deform ation and failure for steep bedding rock slope,namely,toppling deformation.On the basis of former experience,toppling deformation is one peculiar deformation mode belonging to reversal incline and vertical stratified slope .The bedding slopes are different from the counter-tilt slopes completely in mechanical properties. So it is necessary for us to do some research on the tilting deformation failure mechanism.Taking two typical landslides of Bikou reservoir close to the dam for an example,on the basis of clarifying geological environment conditions in the region and basic characteristics factors of the landslides, this paper summarizes basic characteristics and structural characteristics of the bedding slopes where the landslides come into being,and the formation mechanism of the landslides and the rule of the effect of the factors controlling deformation of slope is been carried out mainly by numerical simulation.Through this research,the following rules and conclusions drawn:(1)On the base of the detailed investigation of geological environment and basic characteristics factors of landslides,structural characteristics and deform ation and failure characteristics of landslides are deeply studied , and the basic characteristics and structural characteristics of the steep bedding rock slopes with toppling deformation are summarized and analyzed.(2)Based on the analysis of material composition,structure characteristic genetic mechanism,and other engineering geological characteristics of landslides of Bikou reservoir in Bailong River,the 3D numerica1 models of the geological prototype are established by estimating the ancient topographic and morphologic characteristics and reinstating the glided mass.Using the Distinct Element Method to simulate each evolved stage in the deformation process of the slopes,the results showed that in the process of valley evolution and slope formation and under the maximum principal stress of slope,which is parallel to the surface of slope,rock stratum bends from frontal edge gradually to the inner part of the slope as a cantilever beam.At last its root will be broken off,and a toppling body comes into being. On condition that the maximum shear stress exceed the shear strength in the cracked zone of the slope,it will slide and landslide happens.(3)The displacements of Meng Jiagangou landslide are calculated by distinct element method. Comparison between the simulation results and the field values of earthquake induced displacements shows that the displacements simulated by 3DEC are close to the field values.(4)Then,the deformation and failure rule of slope is researched by the way of numerical simulating deformation and destruction of bedding rock slope with three-dimensional rogram of 3DEC.By taking into account and changing geometric shape,height and angle of bedding slope and angle of interface separately,the influences on toppling deformation of bedding slopes are analyzed. Finally get the following conclusions:①Compared with planar sloped and concave slope, the toppling deformation of convex slope is easier to happen.②In general,it is easy for rock stratum to topple over when bedding dip is more than 60°.③It aggravates slope deformation with the increase of the slope angle. It is more likely for stratum to topple at the condition of the slope angle above 30°.④The deformation increases with height. When the slope is higher than 100m with particular geological environment,bedding dip increasing from 45°to 85°,slope failure mode will transit from sliding-bendin mode to toppling mode.The calculated results accord with the situation of toppling deformation in situ .