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首先建立了反映温度对非饱和土前期固结压力影响的加载-升温(loading thermal,LT)屈服线,而后基于真强度概念并结合潜在强度的确定方法推导出不同温度下非饱和黏土临界状态应力比的理论计算公式;将LT屈服线与反映常温下吸力对土体前期固结压力影响的加载-湿陷(loading collapse,LC)屈服线结合,建立了加载-升温-湿陷(loading thermal collapse,LTC)屈服面,该屈服面综合考虑了温度和吸力对土前期固结压力的影响;最后在临界土力学框架内建立了一个考虑温度影响的正常固结非饱和土本构模型,并将其扩展到超固结非饱和土。与巴塞罗那模型相比,所提出的模型仅增加了一个参数来反映非饱和土的前期固结压力随温度升高而降低的特性。模型能够综合描述温度、吸力以及不同超固结程度对土应力、应变的影响,方便于数值计算和有限元分析。模型预测和试验分析表明,某一固定吸力下升温会使正常固结非饱和土强度提高;对于超固结非饱和土,升温或湿化均会破坏土体超固结,降低软化和剪胀的效果。
First, a loading thermal (LT) yield line, which reflects the influence of temperature on the consolidation pressure of unsaturated soil, was established. Based on the concept of true strength and the determination method of latent strength, the critical stress of unsaturated clay under different temperatures Than the theoretical calculation formula. The combination of LT yield line and loading collapse (LC) yield curve, which reflects the effect of suction at normal temperature on the consolidation pressure of soil, establishes a loading thermal-collapse- , LTC) yield surface. The yield surface comprehensively considers the effect of temperature and suction on the consolidation pressure of the soil in the early stage. Finally, a constitutive model of normal consolidated unsaturated soil considering temperature is established in the framework of critical soil mechanics. It extends to overconsolidated unsaturated soil. Compared with the Barcelona model, the proposed model adds only one parameter to reflect the decrease of the pre-consolidation pressure of unsaturated soils with increasing temperature. The model can comprehensively describe the influence of temperature, suction and different degree of overconsolidation on soil stress and strain, which is convenient for numerical calculation and finite element analysis. The model predictions and experimental analyzes show that the strength of normally consolidated unsaturated soils increases with the increase of temperature under a certain fixed suction. For overconsolidated unsaturated soils, temperature increase or humidification will destroy the overconsolidation of the soil and reduce the softening and dilatancy Effect.