摘要
Four key stress thresholds exist in the compression process of rocks,i.e.,crack closure stress(σ_(cc)),crack initiation stress(σ_(ci)),crack damage stress(σ_(cd))and compressive strength(σ_(c)).The quantitative identifications of the first three stress thresholds are of great significance for characterizing the microcrack growth and damage evolution of rocks under compression.In this paper,a new method based on damage constitutive model is proposed to quantitatively measure the stress thresholds of rocks.Firstly,two different damage constitutive models were constructed based on acoustic emission(AE)counts and Weibull distribution function considering the compaction stages of the rock and the bearing capacity of the damage element.Then,the accumulative AE counts method(ACLM),AE count rate method(CRM)and constitutive model method(CMM)were introduced to determine the stress thresholds of rocks.Finally,the stress thresholds of 9 different rocks were identified by ACLM,CRM,and CMM.The results show that the theoretical stress−strain curves obtained from the two damage constitutive models are in good agreement with that of the experimental data,and the differences between the two damage constitutive models mainly come from the evolutionary differences of the damage variables.The results of the stress thresholds identified by the CMM are in good agreement with those identified by the AE methods,i.e.,ACLM and CRM.Therefore,the proposed CMM can be used to determine the stress thresholds of rocks.
岩石在压缩过程中存在4个关键应力阈值,即裂纹闭合应力(σ_(cc))、裂纹起裂应力(σ_(ci))、裂纹损伤应力(σ_(cd))和抗压强度(σ_(c))。前三个应力阈值的定量识别对于表征岩石在压缩作用下的微裂纹扩展和损伤演化具有重要意义。本文提出了一种基于损伤本构模型的岩石应力阈值定量测量方法。首先,考虑岩石的压实阶段和损伤单元的承载能力,基于声发射计数和Weibull分布函数建立了两种不同的损伤本构模型;然后,引入累积声发射计数法(ACLM)、声发射计数率法(CRM)和本构模型法(CMM)确定岩石的应力阈值;最后,利用ACLM、CRM和CMM识别了9种不同岩石的应力阈值。结果表明,两种损伤本构模型的理论应力-应变曲线与试验数据吻合较好,两种损伤本构模型的差异主要来自损伤变量的演化差异。CMM法确定的应力阈值与声发射方法(ACLM和CRM)确定的应力阈值吻合较好。因此,所提出的CMM法可用于确定岩石的应力阈值。
作者
DU Kun
YI Yang
LUO Xin-yao
LIU Kai
LI Peng
WANG Shao-feng
杜坤;易阳;罗鑫尧;刘凯;李鹏;王少锋(School of Resources and Safety Engineering,Central South University,Changsha 410083,China;Zhongnan Engineering Corporation Limited,Power Construction Corporation of China,Changsha 410014,China)
基金
Projects(2021RC3007,2020RC3090)supported by the Science and Technology Innovation Program of Hunan Province,China
Projects(52374150,52174099)supported by the National Natural Science Foundation of China。
作者简介
Corresponding author:WANG Shao-feng,PhD,Professor,E-mail:sf.wang@csu.edu.cn,ORCID:https://orcid.org/0000-0001-9870-6463。
