Used To Search For New Methods Of Three-dimensional Complex Slope Stability Analysis Of The Sliding Surface

This article puts forward a new method of using random angle to generate random sliding surface, and by studying generation law of random curves search of two-dimensional random sliding surface was simplified into search of approximate curve generated by combination of delineation of different angles and vertical soil slices.Some basic solutions were provided under a number of different circumstances of slopes with complicated shape,a variety of heterogeneous layered soil and water encountered (including the general stability and local stability) in new method. And the new method of search of sliding surface is applied to homogeneous soil slope, stratified slopes and slopes under action of seepage.Then, considering three cases of slope geometry, soil parameters and change of water level in slope, possible of local stability of slope was studied.At the same time,for expanding application of the new method of two-dimensional sliding surface search, through improving new method of a single curve sliding surface search the new methods of multi-segment curve sliding surfaces search and line sliding surfaces search was proposed, and apply them in stratified soil and soil slope with complex shape respectively.As a basic of the new method of a single curve sliding surface, a new method of arbitrary sliding surface generated by mother line and standard line is proposed.For the sliding body of asymmetry in the engineering (including the case of standard line of asymmetric and length of asymmetric) and mother line being not in the largest cross-section of the sliding body along the sliding direction, and slopes with weak interlayer, some solution measures are used.Then these are applied to three-dimensional simple homogeneous slopes and four examples of common excavation and filling compound slope in the engineering, filling embankment at form of hierarchical Level,vertical section of road with flat and oblique slope and the slopes with weak interlayer.By contrast and analysis of calculating, the following conclusions can be obtained. (1)Through comparison and analysis of various examples, it can be obtained that in homogeneous soil, layered soil or soil under steady seepage (including the overall slope stability or local stability), factor of safety calculated by using new method is quite close to previous research, and the critical sliding surface got by using new method is consistent with the actual situation. Therefore those demonstrate the feasibility of the new method.(2) On stability analysis of slope under effect of seepage,the calculated results with non-circular sliding surface are more reliable than with circular sliding surface, and with increase of groundwater level in slope factor of safety of slopes were sharply decline, so effect of seepage is an important factor for occurring of slope instability.(3) In general stability and local stability of slopes,changes of slope geometry, difference between soil, water level in outside and inside of slope and soil material parameters y, c andφchanges may impact occurrence of local instability of slopes, but decrease of dimensionless ratio ofφand c may turn to general stability of slopes.(4) In the layered soil,comparing with factor of safety, the result of multi-segment curve sliding surface method is minimum, followed by single curve sliding surface method, and that of circular sliding surface method is the largest, at the same time from the results of critical sliding surface obtained, while physical properties between soil have large difference, sliding surface performs non-circular arc, and sliding surface between soil is also not entirely consistent, so those can illustrate that multi-segment curve sliding surface method could get closer to actual situation of the critical sliding surface.(5)Research on problems of three-dimensional slope showed that firstly three-dimensional stability is higher than two-dimensional stability in the same slopes and secondly when the fill material and excavation material is inconsistent in excavation and filling compound slope, the sliding instability occurs easier at poor stability of materials, but at the case of material of filling and excavation with same severe y, whetherφ/ c of two materials is equal impacts symmetry and size of the sliding body on a certain extent, and thirdly for the slope of vertical section of road with flat slope, the most potential dangerous sliding surface is more inclined to flat slope section of the slope and oblique slope section of the slope have some positive impact on the slope stability, and fourthly in slope with weak interlayer, when the length of sliding body reaches infinite length its three-dimensional stability tends to two-dimensional stability.In this article there are some innovations as follows:(1)The method of this article is relatively new, and that can not only be applied to stability analysis of two-dimensional and three-dimensional slope,but also easily calculate factor of safety and draw graphics sliding surface through programming in computer.(2) An example of soil slope containing soft interlayer (existence of weak interlayer impact the choose of type of sliding surface) is discussed and analyzed in type selection of sliding surface by using new method, and obtain general calculations model of sliding surface in this case.(3)When considering the effect of seepage, soil slices was seen as three kinds of division and conducted mechanical analysis to derive the formula of buoyancy and penetration of slices in simplified Janbu method respectively.