不同养护条件下黏土热力学性质试验

温度对土的物理力学特性有较大影响,对黏土开展了不同养护条件下的温控三轴试验,研究了黏土在不同温度、不同时间下的热力学特性。试验结果表明：黏土具有热固结性质,随着温度的增加,黏土的固结速度加快,试验固结时间呈下降趋势;在临界温度以下,土体应力-应变曲线呈现软化特性,为脆性破坏;在临界温度以上,土体应力-应变曲线呈现硬化特性,为塑性破坏;黏土具有类似于混凝土“养护温度”的性质,即同一温度作用下,养护时间越长,主应力差越大;黏聚力在临界温度范围以内,随温度升高而降低,而在临界温度以上,随温度升高而增大;内摩擦角在临界温度范围以内,基本不受温度变化的影响,而在临界温度以上,内摩擦角随温度增加而增大;黏土强度随养护时间的增长过程分为快速增长阶段、较快增长阶段、缓慢增长阶段,其最佳养护时间为快速增长阶段和较快增长阶段。

Experimental study on thermomechanical behaviour of clay under different curing conditions

The physical and mechanical properties of soil are greatly influenced by temperature. Triaxial tests under different curing conditions were carried out on clay to investigate its thermomechanical behavior. This paper presents the findings of a laboratory investigation into the thermomechanical behavior of clay. Experimental results show that clay exhibits thermal consolidation properties. As temperature increases, the consolidation speed of clay accelerates, and the consolidation time shows a decreasing trend. Below the critical temperature, the stress-strain curve of the soil presents softening characteristics and brittle failure. Above the critical temperature, the stress-strain curve shows hardening characteristics and plastic failure. Clay exhibits a behavior similar to the “curing temperature” of concrete, where a longer curing time results in a greater principal stress difference. Within the critical temperature range, cohesion decreases with increasing temperature, while above the critical temperature, cohesion increases with temperature. Within the critical temperature range, the internal friction remains unaffected by temperature changes. However, above the critical temperature, the internal friction increases with temperature. The strength development of clay with curing time is divided into rapid growth, followed by a stage of less rapid growth and slow growth. The optimal curing time occurs during these rapid growth stages.