基于Hoek-Brown准则的岩体冻融-荷载耦合损伤模型及其算法研究

A Coupling Damage Model Under Freeze-thaw Cycles and Loading Based on Hoek-Brown Criterion and Its Algorithm Research

针对北方寒区岩体在冻融循环和外荷载作用下产生的耦合损伤问题,基于广义Hoek-Brown准则及连续损伤力学理论,引入冻融-荷载耦合损伤因子,建立了可以表征耦合损伤对岩体强度参数mb、s和弹性模量E产生弱化效应的弹塑性损伤模型;为解决模型在数值实施过程中的奇异点问题,推导了其在主应力空间中的隐式返回映射算法,包括弹性预测、塑性修正和损伤修正30个计算步骤;通过ABAQUS软件的用户子程序接口Umat,实现了模型的有限元求解过程,并利用室内冻融循环试验对模型进行了验证.最后将模型应用于吉林某边坡工程当中,计算了不同冻融次数下边坡安全系数的变化规律.研究结果表明:所建模型能够较好地描述冻融循环与塑性损伤对材料强度和刚度的弱化效应,所编程序能够用于寒区岩土工程安全性评价,对施工设计起到指导作用.

Aiming at the coupling damage problem of rock mass caused by freeze-thaw(F-T)cycles and external load in northern cold region,the elastoplastic damage model introducing F-T and load coupling damage factor was established based on generalized Hoek-Brown criterion and continuum damage mechanics.The model can represent the weakening effects of coupling damage on rock strength parameters mb、s and elasticity modulus E.In order to solve the singularity problem in numerical implementation of the model,the fully implicit stress mapping algorithm in principal stress space was deduced which included three steps of elastic trial,plasticity correction and damage correction.The numerical procedure was implemented by subroutine interface Umat in ABAQUS.Then the model was verified by a triaxial F-T compression test in laboratory.Finally,the model was applied to a slope stability analysis in Jilin province.The results indicate that the model can describe the weakening effect on the strength and stiffness of material caused by F-T cycles and plastic damage.The compiled program can be used for safety evaluation and guidance to the construction design of geotechnical engineering in cold region.