An Analytical Method Of Stability For Soil Slope Based On The Unified Slip-line Theory

Along with the increasing progress of infrastructure construction,all kinds of slope problems are inevitably.In practical engineering practice,it is necessary to make an accurate evaluation of the slope stability safety coefficient,If the slope is not guaranteed enough stability safety coefficient,the slope is easy to be unstable under the influence of various internal and external factors such as slope excavation and rainfall.Whats more,in the less-stable slope treatment engineering,the study of slope stability is the premise of slope treatment for solving less-stability is the first thing to do.Therefore,the study of slope stability analysis method is of great practical significance,and the accurate evaluation of slope stability safety coefficient in engineering practice can take appropriate and effective reinforcement measures,which will improve the economic benefits of the project.First of all,this paper expounds the basic principle of the theory of slip-line,then combining with the unified strength theory introduces the process of soil slopes and unified ultimate slope curve using a graph method.And on this basis,this paper comes up with a method of soil slope stability coefficient with unified limit slope curve and the positional relationship of the slope lines,which is named as unified limit slope curve method.The unified limit slope curve method does not presuppose the sliding surface of the slope,and has qualities as simplicity and feasibility.For homogeneous soil slopes,the graph method can be used to obtain the unified limit slope curve quickly and accurately.The unified limit slope curve method was used to calculate the stability coefficient of the homogeneous soil slope in the literature,and the results obtained are consistent with those obtained by the existing methods,indicating that the results obtained by the present method are reliable.The safety status of several homogeneous soil slope samples was also judged,the results obtained by the unified limit slope curve method are more accurate than those obtained by other methods such as the stress state method and the limit curve method,which indicates that the unified limit slope curve method can accurately determine the state of the homogeneous slope.Taking the roadside slope project of Panzhihua airport as an example,the judgment result of the unified limit slope curve method is consistent with the slope state in the actual project,which indicates that the unified limit slope curve method can be well applied in the practical project.The sensitivity analysis of five main factors affecting the stability coefficient of homogeneous soil slope is carried out by using the grey correlation method,and the influence curves of each factor are drawn.The results show that among the six factors,the intermediate principal stress coefficient is the most sensitive to the slope stability safety coefficient,followed by cohesion,internal infraction angle,slope height,and the less sensitive factor is slope angle.The intermediate principal stress coefficient has a great influence on the slope limit curve and the safety coefficient.For layered soil slope,the traditional method of treating the boundary surface of soil layer is to treat it as a special stress break line,and the stress break occurs through the slip line of the boundary surface of soil layer.On this basis,the method for the simplified processing,namely,taking the points near the boundary surface of soil as calculation points of interface stress discontinuity in the graph method,reduced the stress discontinuity calculation steps after extending slip-line to soil boundary surface,and greatly reduces the work of using graph method to calculate unified slip line field and limit slope curve.As long as the calculation distance is small enough,the error can be controlled within a reasonable range.A case study of layered soil slope in the literature was selected to calculate the stability safety coefficient by using the unified limit slope curve method,the calculated results are in good agreement with the calculated results of the existing methods,and can accurately judge the state of the slope.By using particle follow code numerical simulation software PFC to simulate Xigeda soil compression indoor test the microscopic parameters of Xigeda soil are obtained.According to these microscopic parameters,numerical simulation software PFC was used to study and analyze the stability of homogeneous Xigeda soil slope,and the simulation results of the slope stability of particle follow code are consistent with the judgment results of the unified limit slope curve method.The numerical simulation software PFC can directly observe the whole process of the failure of the Xigeda soil slope and its sliding surface.