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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。
In order to investigate the deformation characteristics and failure mechanism of lime-treated expansive soils, the mechanical properties of Jingmen lime-treated expansive soils with compaction degree of 95% were studied under uniaxial, lateral and triaxial compressive stress conditions. The experimental results show that limestone has high stiffness and strength even after saturated wetting. Under uniaxial compression, the failure of limestone is typical brittle failure in either saturated or unsaturated state. Under the condition of triaxial compression, lime The soil is sheared before shrinkage and accompanied by strain hardening. The dilatancy is about to rupture and then appears as strain softening. The confining pressure has a certain inhibition effect on the brittle failure of lime soil and the dilatancy after failure, but even at 200 kPa Press, the sample is still brittle damage. On the basis of identifying the stress and deformation mechanism of lime soil, the Duncan model was used to describe the properties of compression hardening, shearing shrinkage and strain hardening before brittle failure. The corresponding model parameters were calibrated and verified by numerical simulation and parallel experiments The applicability of the model and the reliability of the parameters.