State parameter–based thermomechanical constitutive model for saturated fine-grained soils

Abstract

This paper presents a two-surface constitutive model for describing thermomechanical behaviour of saturated fine-grained soils at both normally consolidated and overconsolidated states. A thermal-dependent stress ratio-state parameter relation is adopted to account for the effects of temperature on the shape of the state boundary surface (SBS) of soils. In the model, both the size and the shape of the SBS are allowed to vary with temperature, which is evidenced by thermal variation of the mechanical yield loci and the shifts of the normal consolidation line (NCL) and the critical state line (CSL) upon heating and/or cooling. A thermal yield surface is added for modelling the isotropic thermal deformation of soils more accurately, in particular at overconsolidated states. The mechanical and thermal yield mechanisms are coupled by the temperature-dependent preconsolidation pressure which is controlled by a volumetric hardening law. Based on experimental observations, a nonlinear relationship between the spacing ratio and temperature changes is defined and a simple thermal dependent non-associated flow rule is proposed. The model is validated against some selected experimental results of several soils tested under various mechanical and thermal paths such as drained isotropic heating and cooling, drained and undrained triaxial compression at non-isothermal conditions.

Thermo-elasto-plastic constitutive model of saturated clay considering state-dependent

“…考虑正常固结线和临界状态线随 温度升高向下移动的特点, Zhou 和 Ng [16] 建立了小应 变下饱和黏土的边界面热力学模型, 但模型不能模 拟超固结土的应变软化特性. Zhu 等 [17] 将荷载屈服面 和温度屈服面进行耦合, 采用温度相关的非关联流 动法则, 建立了状态相关的饱和细粒土双面热力学 模型. 基于热力学原理, Golchin 等 [18] 提出了一个新 的耗散势函数, 并将屈服应力和临界状态应力比作 为温度的函数, 建立了细粒土的热力学本构模型.…”

“…2.5 本构关系 在热弹塑性理论框架中, 通常假设温度变化只 引起弹性体积应变，而弹性剪切应变不受温度的影 响。总应变增量可以分为三部分 [15][16][17][40][41][42] : 弹性应变 增量 ( , )…”