A Unified State-Dependent Constitutive Model For Granular Soils And Clays

Granular soils,clays and their mixtures are widely used as fillers in the field of civil engineering.The strength and deformation related problems will cause many disasters such as deterioration,instability and even failure of structures.It is of great engineering value and theoretical significance to study the mechanical properties of granular soils,clays and the mixtures.In view of the similarities and differences of strength and deformation characteristics of granular soils and clays,a unified statedependent constitutive model of granular soils and clays was established in this paper.The main work as follows:(1)A new particle breakage index was proposed,a simple and clear evolution law of critical state line was established considering the influence of particle breakage,and state parameters was modified.Based on the statedependent constitutive model proposed by Li et al.,the state-dependent constitutive model of granular soil considering particle breakage was established.(2)The sub-loading surface was used to improve the yield function,and a new state parameter was proposed based on the sub-loading surface.Furthermore,the limit void ratio was introduced to describe the phenomenon of the existence limit of particle breakage under high stresses.Based on these two points,a sub-loading surface constitutive model under high stress of sands was established with consideration of particle breakage.(3)According to the similarity of mechanical properties of granular soils and clays,a unified description of critical state line and normal consolidation line for both granular soils and clays were established,and test data of granular soils and clays were selected for verification.On the basis of the loading surface,the overconsolidation parameters of overconsolidated clays were introduced into the newly established state parameters,and the state-dependent constitutive model of overconsolidated clays was established.The established state parameters can take into account both particle breakage and overconsolidation.Finally,the parameters of the established constitutive model were analyzed,and a preliminary discussion on the constitutive model in describing the mechanical properties of the mixtures is discussed.This thesis includes 46 figures,8 tables and 88 references...