未冻结和冻结粗砂的本构模型研究

Constitutive modelling of a coarse sand under unfrozen and frozen states

在寒区进行基础设施建设,需要了解土体在未冻结和冻结状态下的力学特性.为研究粗砂在未冻结和冻结状态下的本构行为,本文首先将颗粒破碎率引入砂土的弹性定律和硬化规律中,建立砂土的临界状态模型,对加载过程中的变形和破碎情况进行了研究.同时,采用广义双曲线模型描述了冰夹杂相的力学行为.在基质体和夹杂体本构方程基础上,通过在细观应力和宏观应力之间引入简化的应力集中张量,建立了基于细观力学的冻结砂土模型.通过与不同温度和不同应力路径下的三轴试验结果对比,验证了本文所建立的冻结粗砂宏细观本构模型.

Construction of infrastructure in cold regions requires an understanding of the mechanical characteristics of soils under unfrozen and frozen states.For investigating the constitutive behaviors of a coarse sand under unfrozen and frozen states,a critical state model considering the effect of particle breakage was developed,followed by the establishment of a mesomechanical-based frozen soil model based on homogenization theory.The relative breakage,defined by grain size distributions(GSDs)and evaluated by modified plastic work,was introduced into the elastic law and hardening rule of sandy soil.The deformation and relative breakage properties of sandy soil during the loading process were examined by the developed particle crushing model.Meanwhile,the behavior of the ice inclusion phase was described by a generalized hyperbolic model.On the basis of constitutive equations of the sandy matrix as well as ice inclusions,a mesomechanical-based model of the frozen sandy sample was established by introducing a simplified stress concentration tensor between meso and macro stresses.Compared with triaxial test data,the mesomechanical-based model developed in this study reproduced the constitutive behavior of frozen sandy sample at different temperatures and at various stress paths well.It is hoped that the results of this work can serve as a reference for the constitutive simulation of soils in cold regions.