影响因子修正的新型岩石损伤统计本构模型

Newly modified damage statistical constitutive model of rock based on impact factor

建立能够体现岩石的初始损伤以及损伤部分仍能承受一定应力的新型岩石损伤模型.基于损伤演变过程提出新的损伤定义,将损伤部分分为损伤材料和因材料损伤而变化的微缺陷,提出损伤材料与因材料损伤而变化的微缺陷之间的影响因子γ,给出其确定方法,并研究其基本性质;通过岩石微观受力分析,建立岩石损伤模型;深入探讨岩石有效应力与名义应力的关系,引进岩石微元强度,服从对数正态分布,建立考虑损伤阈值影响的岩石损伤统计本构模型,并提出确定分布参数的方法.结果表明:该模型能够充分反映岩石损伤阈值的影响及应变软化特性,且参数物理意义明确,应用较为方便;与试验结果比较,本文模型理论曲线与试验曲线匹配度达87.2%,高于前人模型曲线的81.3%,说明该模型更为合理、可行.根据本文理论得出的损伤演化曲线符合S型曲线规律,能够很好地反映岩石压缩过程中的变形阶段划分.

The paper aims to establish a new rock damage model which could simultaneously represent the initial damage and the damage part under stress.Based on the rock damage process,a new definition of damage was proposed,and the damage was classified into two types：the damage material and micro defects due to the change of damage material.An impact factorγrepresenting the relationship between the two types of damage and the method of determining the parameters were put forward subsequently.Then,a new rock damage model was established through the analysis of microscopic stress of rock.Moreover,on the basis of analyzing the relationship between effective stress and nominal stress,the micro-unit strength which obeys lognormal distribution was introduced;a statistical damage constitutive model of rock which considers the influence of damage threshold was established,and the method of determining the distributed parameters were presented.The results show that the model can fully reflect the influence of damage threshold and the strain softening characteristics of rock mass,and the physical meanings of the model parameters are explicit.This model is more convenient for application.Finally,through the comparative analysis of existing research results,the compatibility between modeling theoretical curve and experimental curve is up to 87.2%,higher than the previous model,whose matching rate is 81.3%,indicating that the proposed model is more rational and feasible.Besides,damage development curve derived from this paper accords well with S curve,and can well reflect deformation stages of the compression process of rock.