Stability Analysis Of Three-Dimensional Cracked Slope And Relations Between Landslide Volume And Area

Slope stability analysis is an important research in the field of geological engineering.The slope disaster has always brought great threat to the engineering construction,so it is particularly significant to research the failure characteristics of slope,which can provide advice for landslide disaster prevention and slope reinforcement.Previous studies focused on shear failure mode without considering the effect of tensile strength in slope.The influence of tensile stress on slope stability had been confirmed in field survey and model test.In recent years,the tension-shear failure mechanism of slope based on plane strain has quantitatively discussed the variation of slope stability with tensile stress,however,in three-dimensional slope,the influence of tensile stress on slope stability and failure mechanism is still needed to research.In this study,pre-existing tensile crack was introduced into the tensile stress zone of the rear part of the slope to consider the effect of tension failure.Based on the upper limit theorem and combined with Monte Carlo method and Sequential Quadratic Programming,the stability and failure mode of three-dimensional cracked slope under static and seismic load were studied respectively.Taking the critical failure surface of the slope as the sliding surface,the relationship between the volume and area of the landslide was analyzed,and a prediction model for evaluating the volume of the landslide through the area was constructed.The following results were obtained:（1）The constraint width has an important influence on the stability,failure surface and failure mode of three-dimensional cracked slope.The stability reduces with the increase of constraint width,but the decrease does not show a uniform change.With the increase of the constraint width,the depth of the slip surface is gradually increasing,and the position of the crack is gradually away from the crest of slope.Toe failure is the main failure mechanism of three-dimensional cracked slope,however,when the constraint width is small（B/H<0.8）the face failure will occur and when the constraint width enlarge（B/H>1.5）the base failure will also occur.（2）The internal friction angle and slope angle have influence on the stability and failure surface of three-dimensional cracked slope.The reducing rate slows down with the increase of the slope angle.The larger the internal friction angle is,the greater the reduction of the stability is.The depth of the crack is positive correlation to the slope angle and negative correlation to the internal friction angle.（3）The seismic load has a significant influence on the three-dimensional cracked slope.The larger the seismic load is,the greater the reduction of the stability is.The increasing internal friction angle strengthens the reducing effect,while the increasing slope angle weakens reducing effect.At the same time,the seismic load will amplify the influence of constraint width on the stability.With the increase of seismic load,some cracks that could not have been considered will become part of the failure surface,and the situation of face failure and base failure mechanism will increase.（4）Empirical model is an effective method to evaluate the volume of landslide.The best volume-area fitting formula obtained in this study is V=0.138As^1.453（R²=0.9939）,which is proved correct by comparing with the field surveys empirical formula.It can be found through parameter analysis that depth of sliding surface,slope angle,constrain width and friction angle have great influence on the volume-area relationship,while seismic load and crack have little influence.