Study On Compression Curve And The Coefficient Of Earth Pressure At Rest For Cohesionless Soil Based On Hypoplastic Constitutive Model

This paper presents a hypoplastic constitutive model and hypoplasticity. These models are based on nonlinear tensorial functions and are developed without recourse to concepts of elasto-plasticity theory such as yield surface, plastic potential, flow and hardening rules and decomposition of deformation into elastic and plastic parts. The paper also presents the hypoplastic model that is capable of capturing the salient features of granular materials, in particular, for problems involving extremely low stress levels or extremely high stress.This paper investigates the determination of granulate hardness hs and exponent n in a hypoplastic constitutive model, and presents a hypoplastic constitutive model and hypoplasticity.According to hypoplasticity and optimization , we put forward a modificatory method of determination of n and hs using iterative operation .According to the hypoplastic constitutive model, the stress-strain equation of granular materials can be presented in oedometer test. The further investigation of the equation shows that it can be used to determine stress-strain relation in oedometer test.On the basis of general principles of mechanics and critical state soil mechanics theory , a theoretical formula determining the coefficient of earth pressure at rest for cohesionless soil is derived by means of combining hypoplasticity with critical state soil mechanics. The formula has a simple form and is only related to the effective angle of internal friction of soil . There is a slight difference between the calculated value of the formula and that of other formulae. The further investigation of the formula shows that it can be used to determine the coefficient of earth pressure at rest of cohesionless soil.