Multiscale Computation For Mechanical Properties Of Expansive Soil With Cracks And Study On Slip Path Of The Slope

A large number of primary structural planes were found in the expansive soil slopes.The length of these primary structural planes covers a large span,ranging from a few centimeters to tens of meters.The stiffness and strength of the primary structural planes are much lower than the surrounding soil,which will affect the stability of the slope.At present,in the analysis of stability of expansive soil slope,only the deterministic weak interlayer has been taken into consideration,and the primary structural planes are treated as homogeneous body,which causes it difficult to reflect the influence that the primary structural planes have on slope stability.Therefore,the study on the influence that the primary structural planes have on macro mechanical parameters of expensive soil from microcosmic view has an important significance on the analysis of slope’s stability and the prognosis of slip band of expansive soil slope.In this paper,the author takes advantage of statistical model of expansive soil with primary structural planes,then studies the influence that minute primary structural planes have on macro mechanical parameters of expansive soil from microcosmic view,and gets the macroscopic stiffness and strength parameters in view of the minute primary structural planes.Then the author takes these parameters as the calculated parameters of finite element numerical simulation,takes the deterministic weak interlayer and hydro-mechanical coupled effect into consideration,analyzes the sliding mechanism of expansive soil slope with random primary structure planes,and puts forward the searching method of the sliding path of expansive soil slope with random primary structure planes.Firstly,a systematical and full statistical work in the field is done to a large number of appeared primary structural planes from different dimensions during slope excavation.The distribution laws of each morphological feature character of the primary structural planes are analyzed in corresponding scales,based on which the primary structural planes are reproduced with computer,and the random structure plane statistical models of corresponding scales are set.Secondly,stiffness and strength parameters of non-crack soil and primary structural planes are captured according to a series of stiffness and strength tests.Based on swelling text under load,formula of linear expansion coefficient is captured.Thirdly,based on the idea of double scale asymptotic expansion,the author designs multiscale computational method of macroscopic stiffness parameters of swelling soil with primary structural planes.Taking this slope for specific numerical example,the author homogenizes the stiffness parameters of the primary structural planes whose length bellow 4m from multiple scales,thus gets corresponding homogenized stiffness parametersFourthly,based on multi-scale analysis method and indoor triaxial test,combined with finite element numerical simulation,multiscale numerical text method of macroscopic strength parameters of swelling soil with primary structural planes is put forward.Taking this slope for specific numerical example,the author homogenizes the strength parameters of the primary structural planes whose length bellow 4m from multiple scales,thus gets corresponding homogenized strength parameters.At last,homogenized stiffness parameters,strength parameters and expansion coefficient are taken as finite element numerical simulation parameters of the slope.Considering hydro-mechanical coupled effect and the primary structural planes whose length are more than 4m,collapse mechanism of swelling soil slope with random primary structure planes is studied.According to the result of finite element stress field of swelling soil slope with random primary structure planes,two sliding path search algorithms based on Dijkstra algorithm and Floyd algorithm are proposed respectively.Through statistics of multiple slipping path searching results of expansive slopes with random primary structure planes,the slip bands based on two different search algorithms are obtained.Through comparative analysis,the differences between two kinds of slope sliding path search algorithms are obtained.