Multiscale Analysis For Slope Stability

Stability of slope is a multi-scale problem,and the slope model can be simplified into three different scales: microscopic particle scale,mesoscopic material scale and macroscopic place scale.In the study of slope stability,the existing results are only based on the theories of continuous medium mechanics or discontinuous medium mechanics to research the scale or cross-scale,which is lack of systematacially comparative analysis.Simultaneously,the traditional PFC-FLAC coupling interface transfers two software data by means of a simple Socket I / O communication interface,and the calculation process is complex.Combining with strength reduction method in this paper,FLAC and PFC are respectively used for stability analysis of the slopes,and the continuous-discrete coupling algorithm based on gravity difference method is used to analyze the slope stability.The main research results as follows:1.Using the software of FLAC to numerically simulate the stability of the slope by the means of continuous elements.The variation of displacement,shear zone and the plastic zone in the slope under the different reduction coefficients are recorded to reveal process of the failure of the slope.At the same time,interconnected shear zone and the characteristic point of displacement mutation can be used as the criterion of instability slope,and the sensitivity of the continuous grid element is analyzed and discussed.2.Based on the triaxial consolidation draining numerical tests of PFC and two parameter matching methods of macroscopic shear strength(Mohr circle of stress envelope)and material constitutive standard value(stress-strain curve),the control variate method is used to summarize the relationships between the mesoscopic Parameters and the macroscopic parameters,and the given macroscopic parameters are demarcated in the form of mesoscopic Parameters.3.Using the software of PFC to numerically simulate the stability of the slope by the means of discrete elements.The macroscopical phenomena of the whole process of instability slope are analyzed from the aspects of displacement field,velocity field and corner field.The formation and evolution of slope shear zone are analyzed in detail,as well as the mesoscopic mechanism changes of the sliding body and the stable body,such as the evolution of the corner,force chain,contact and porosity.Revealing the changes of the internal mechanism in the process of the instability slope.At the same time,the similarities and differences as well as the advantages and disadvantages of the discrete elements slopes and the continuous elements slopes are analyzed and discussed.4.The continuous-discrete coupling algorithm based on gravity difference method is used to analyze the slope stability,which verifies the validity of the coupling algorithm in FLAC3 D.At the same time,coupling algorithm is applied to the three-dimensional slope model and the stepwise coupling concept is put forward,which effectively solves the problem of grid dependency in the existence of continuous elements.