A Multi-shear Bounding Surface Model For Granular Soil-structure Interface

There are a large number of soil-structural materials in the construction of civil engineering,water conservancy,transportation and other projects,which have very important engineering application value.Reasonable description of the mechanical properties of the interface between soil and structure is of great significance for the correct evaluation of the interaction between soil and structure.Because the interface between soil and structure is affected by both structure and soil,its mechanical properties are different from those of soil and much different from structural materials.The interface has more complex mechanical properties,including strain localization,stress concentration,large shear deformation,and closure,slip and other complex conditions.In order to establish a reasonable constitutive model of the interface between granular soil and structure and correctly analyze the strength and deformation characteristics of the interface and carry out numerical simulation,this paper presents a three-dimensional multi-mechanism boundary surface model of the interface between granular soil and structure and numerical simulation with multi-group the interface between granular soil and structure contrast,the specific research work and results are as follows:(1)During the deformation of soil-structure systems,the interface zone usually with a very thin width between granular soil and structure may experience the concentration in stress and strain,and its behavior is quite different from that of adjacent materials.The interface may significantly affect the global response of soil-structure systems.This paper presents a multi-shear bounding surface model for simulating the constitutive response of interfaces between granular soil and structure subjected to different types of loadings.Following the slip theory of plasticity,the model is formulated by decomposing the macro response of interfaces into a macro normal response and a set of orientated micro shear responses associated with virtual micro shear structures in the shear plane.This discrete approach provides a simple and effective means to predict the macro shear response of interfaces by superposition of individual responses from all micro shear structures.Each micro shear structure characterizes an individual micro shear response and an individual micro normal response produced by dilatancy.Two relationships on stress-strain and stress-dilatancy at a micro level are established for each micro shear structure.By introducing a state parameter dependent on the critical state of soils,the model is suitable for predicting the constitutive response of interfaces under various normal stresses and soil densities with a single set of model constants.(2)The monotonic and cyclic shear tests of different granular soils and structural interfaces including coarse-grained soil structural interfaces and sand structural interfaces under two-dimensional and three-dimensional conditions were simulated and the model simulation results were compared with the experimental results.The model simulation results of the coarse-grained soil and the structural interfaces under different experimental conditions with different relative compactness and different positive pressure are in good agreement with the experimental results.The model can reasonably describe the nonlinear mechanical behavior of the interface between granular soil and structure.(3)Based on the three-dimensional multi-mechanism boundary surface model of the interface between granular soil and structure,this paper introduces plastic work to consider the particle breakage energy of the material to consider the effect on critical state lines to improve simulation accuracy of the original boundary surface model.The simulation results of the improved model are in good agreement with the experimental results.The model can reasonably reflect the particle crushing characteristics of the interface between granular soil and structure,and the plastic effect can be better considered by the plastic work.It can simulate the particle crushing and mechanical properties under full load of material.