一种考虑黏聚强度的改良土弹塑性本构模型

An elastoplastic constitutive model incorporating cementation effect of stabilizer-treated soils

改良土中土颗粒和水化物形成具有一定结构的聚合体而表现出较强的结构性。与重塑正常固结土相比,改良土的结构性更强且具有一定的超固结比。在变形发展过程中,由于聚合体结构逐渐破坏,黏聚强度逐渐损失,土体表现出应变软化的力学特性。基于适用于超固结重塑黏土的统一硬化模型,引入改良土黏聚强度及其随塑性变形的演化规律,对统一硬化参数进行了修正,并采用更适用于改良土的非关联的流动法则,建立了一个可以较好地描述改良土力学特性的弹塑性本构模型。通过与水泥改良土和石灰改良土的三轴剪切排水试验的结果进行对比,该模型能够较为合理地描述改良土加载过程中黏聚强度损失对其力学特性的影响。黏聚强度的存在导致土体表现出超固结土的特性,当黏聚强度损失时会加剧土体的软化速度。

Stabilizer-treated soil possesses unique structures due to the cementation of soil particles and cement-hydrate. Compared with remolded normally-consolidated soil, treated soil usually holds a strong structure and overconsolidation ratio. Treated soil exhibits softening behavior due to the loss of cementation induced by the decay of bonded structure during the development of deformation. An evolution rule of cementation effect is proposed to consider the change of cementation strength with shear strain. The hardening parameter in UH model is modified and an elastoplastic constitutive model incorporating cementation effect for stabilizer-treated soils is proposed, in which non-associated flow rule is used. The comparison between predicted mechanical behaviors of cement-treated soil and lime-treated soil with triaxial compression test results indicate the validation and accuracy of the proposed model. Consideration of the contribution of cementation effect can describe the mechanical behaviors of stabilizer-treated soils. The soil behaves like overconsolidated soil due to the cementation strength, while the softening is faster with the decrease of cementation strength during deformation.