An elastic-viscous-plastic structured UH model

Zhu Enyang,Wang Yihe,L Wang,V Yepes

doi:10.1051/e3sconf/202124801033

Abstract

On the basis of the structured unified hardening model (structured UH model) considering soil structured collapse, the time effect is take into account, and an elastic-viscous-plastic structured UH model is extended. In the presented model, the moving normal compression line (MNCL) is extended to a moving instant normal compression line (MINCL) for simulating both soil structure effect and time effect. Then the instance plastic strains irrespective of time effect are calculated by referring the MINCL, and the plastic strains due to time effect are calculated by referring the traditional instant normal compression line. Comparisons between test data and model simulation indicate that the presented elastic-viscous-plastic structured UH model is qualified to simulate the combined actions of soil structure and time effects both in compression and in shearing.

Highlights

Soil structure is widely existed in natural soils, which leads two main effects on the mechanical properties: (1) existence of soil structure leads greater strength than the corresponding reconstituted soils. (2) Decay of soil structure cause greater volumetric deformation than the corresponding reconstituted soils
In constitutive model expression, it is necessary to take into account the influence of both the soil structure and the time dependence
By introducing a moving normal compression line (MNCL), the unified hardening model(UH model) for reconstituted soil was extended to a structured UH model mainly considering soil structure collapse[7]

Summary

Introduction

Soil structure is widely existed in natural soils, which leads two main effects on the mechanical properties: (1) existence of soil structure leads greater strength than the corresponding reconstituted soils. (2) Decay of soil structure cause greater volumetric deformation than the corresponding reconstituted soils. The stress-strain relationships of soils are usually considered to be time-dependent, especially for soft clays. According to the microscopic deformation mechanism of natural clay, the deformation of structured soil is divided into three phases as elastic, structural strength damage and rebounded soil, and an elasto-viscoplastic damage model was developed[1]. Taking into account the non-linear feature of semi-logarithmic compression curves for natural clays as well as the variation behavior of creep rate related to the stress level and consolidation duration time, a modified elastic visco-plastic model was proposed[5]. After proposing a new concept of viscoplastic strain rate lines and a new description for the progressive destruction during one-dimentional loading on structured clays, a one-dimentional elastic visco-plastic model considering destruction effects was established[6]. The structured UH model is attempted to be extended to an elastic-viscous-plastic structured UH model (EVP structured UH model)

EVP structured UH model

Model Evolutions

Model prediction