石灰改良膨胀土的应力-应变-强度特征与本构描述

为探讨石灰改良膨胀土的变形特征与破坏机制，以压实度为95 %的荆门石灰改良膨胀土为研究对象，开展了单轴、侧限、三轴压缩应力状态下的力学性质试验。试验结果表明：即使湿化饱和后石灰土也具有较高的刚度与强度；单轴压缩状态下，无论饱和还是非饱和状态，石灰土的破坏都为典型的脆性破坏；三轴压缩状态下石灰土破坏前剪缩，同时伴随应变强化，即将破坏时开始剪胀，随后表现为应变软化；围压对石灰土的脆性破坏与破坏后的剪胀有一定的抑制作用，但即使在200 kPa围压下，试样仍发生脆性破坏。在辨明石灰土应力、变形机制的基础上，选用Duncan模型描述其脆性破坏前表现出的压硬性、剪缩性与应变强化特性，标定了相应模型参数，通过数值模拟与平行试验的对比验证了模型的适用性与参数的可靠性。

Stress-strain-strength behaviour and constitutive description of lime-treated expansive soil

This paper investigates the deformation characteristics and damage mechanism of the lime-treated expansive soil.A series of mechanical property tests under uniaxial compression,one-dimensional consolidation,and triaxial compression are carried out for Jingmen expansive soil.The results show that the lime-treated soil remains fairly stable stiffness and shear strength even after saturated.Under uniaxial compression,whether unsaturated or saturated,the brittle failure occurs for the lime-treated expansive soil,whereas the untreated expansive soil has considerable plastic deformation capacity.On the other hand,under triaxial compression,the lime-treated samples present shear contraction and strain hardening before failure,with the shear dilatancy when the sample was about to failure and strain softening after failure.Moreover,it is observed that the confining pressure had an inhibitory effect on the brittle failure and the shear dilatancy,but even under the confining pressure is 200 kPa,the deformation of the sample is very small at the failure time,which demonstrates the brittle failure.Based on the mechanism analysis,the Duncan model is selected to describe the stress-strain-strength behaviour of the lime-treated expansive soil.The model parameters are calibrated from the aforementioned tests.The comparisons between the parallel tests and predicted results validate the selected model.