Non-linear elastic model incorporating temperature effects

Yang Xiao,Hanlong Liu,Hong Liu,Yufeng Gao,Qingsheng Chen,Jing Peng

doi:10.1680/jgere.17.00015

Abstract

The objective of this paper is to present a non-linear elastic model, considering temperature effects, that engineers can readily use to predict the mechanical behaviours of soils in geotechnical applications. Instead of using hyperbolic and exponential models, a non-linear equation is first formatted to describe the tangent moduli for saturated clays by introducing only one additional parameter (i.e. θ). By extending the non-linear equation, a new simplified non-linear elastic model is obtained that is capable of capturing well the stress–strain relationship of saturated clays at room temperature. Thereafter, based on experimental results, the relationships between cohesion, internal friction angle, index, tangent bulk modulus and temperature are developed and incorporated in the non-linear elastic model. A revised semi-regression method is also developed to determine the relationship between the additional model parameter θ and temperature. In this model, all of the eight parameters for the model have clear physical meanings and could be readily obtained by performing temperature-controlled triaxial tests. The accuracy and general applicability of the proposed method was checked by comparing its predictions with experimental results on saturated clay under various stress-path and temperature conditions as well as existing solutions proposed elsewhere.

Highlights

Graham et al (2001) revised the Cam-clay model to consider the effects of temperature on the volume changes, pore water pressures and shear strengths for both normally consolidated and overconsolidated clays
The main objective of this paper is to propose a new non-linear elastic model to capture the mechanical behaviours of saturated clays incorporating effects of temperature based on the general framework of the power function and the regression analysis method
A new isotropically thermal mechanical constitutive model for normally and lightly overconsolidated clays was developed in present work by extending the existing hyperbolic model (Duncan and Chang, 1970) and exponential model (Gitau et al, 2006)

Summary

Introduction

The volume change for saturated soils performs a transition from contractive to expansive behaviour during drained heating or the temperature cycle with increasing overconsolidation ratio (OCR) (Abuel-Naga et al, 2006; Baldi et al, 1988; Cekerevac and Laloui, 2004; Romero et al, 2005) or relative density (Ng et al, 2016). Many advanced thermo-mechanical constitutive models have been proposed to evaluate the mechanical behaviours of saturated and unsaturated soils undergoing temperature changes (Coccia and McCartney, 2016; Modaressi and Laloui, 1997; Najari and Selvadurai, 2013; Wang et al, 2016). Graham et al (2001) revised the Cam-clay model to consider the effects of temperature on the volume changes, pore water pressures and shear strengths for both normally consolidated and overconsolidated clays. By employing the framework of the modified Cam-clay model, Cui et al (2000) proposed a temperaturedependent model, which could be capable of predicting well the plastic strains at higher OCR values. Graham et al (2001) revised the Cam-clay model to consider the effects of temperature on the volume changes, pore water pressures and shear strengths for both normally consolidated and overconsolidated clays. Hamidi et al (2014) used the relationships of the isotropic compression curves for saturated clays at various temperatures to find a new thermal–elastic–plastic mechanical model incorporating the stress history influence

Objectives

Findings

Conclusion