摘要
压缩作用下岩石内部细观裂纹扩展导致岩石产生损伤,其对岩石变形、强度等力学特性有着重要影响;然而,岩石内部裂纹扩展与剪切特性(黏聚力、内摩擦角及剪切应力)动态演化关系很少被研究。基于裂纹扩展机制推出的岩石应力-应变本构模型,并结合摩尔-库仑失效准则,推出了在岩石应力-应变关系峰值应力(对应岩石压缩强度)状态时,本构模型细观力学参数与岩石黏聚力、内摩擦角及剪切强度之间的状态关系。然后,引入岩石应力-应变本构关系塑性变形阶段服从摩尔-库仑屈服准则的力学流动规律,进而将已推出的应力-应变关系峰值状态点所满足的细观力学参数与黏聚力、内摩擦角关系,推广到岩石进入塑性变形后,岩石内部裂纹扩展(或应变)与黏聚力、内摩擦角及剪切应力动态演化的理论关系。随着裂纹扩展或应变增加,黏聚力、内摩擦角及剪切应力先增大,达到一个峰值点后减小,该结果与应力-应变本构曲线变化趋势相对应。通过试验结果验证了所提出理论结果的合理性。并讨论了初始裂纹之间摩擦系数对黏聚力、内摩擦角及剪切应力随裂纹扩展或应变演化规律的影响。
The damage of brittle rock is induced by its microcrack growth which significantly affects the deformation and strength of rocks subjected to the compressive loadings.However,the relationships between microcrack growth and the variable shear properties(cohesion,internal friction angle,and shear stress)are rarely studied.In this study,the relationships between internal friction angle,cohesion,shear strength and micro-parameters at the peak point of stress-strain relationship are proposed,according to the stress-strain relationship triggered by crack growth and the Mohr-Coulomb failure criterion.By introducing the Mohr-Coulomb yield criterion,the theoretical expression is established for dynamic variations of cohesion,internal friction angle and shear stress along with microcrack growth or strain at plastic deformation phase of brittle rocks.Cohesion,internal friction angle,and shear stress firstly increase until to maximum values,and then decrease with the increasing crack growth or axial strain in brittle rocks under compressive loading,which is corresponding to the stress-strain constitutive curves in triaxial compressive tests.Finally,the rationality of the proposed theoretical expression is verified by comparing with the experimental results.Besides,the effects of friction coefficient between microcrack interfaces on the relationships between cohesion,internal friction angle,shear stress and crack growth or axial strain are discussed.
作者
李晓照
戚承志
邵珠山
屈小磊
LI Xiao-zhao;QI Cheng-zhi;SHAO Zhu-shan;QU Xiao-lei(Beijing Advanced Innovation Center for Future Urban Design,School of Civil and Transportation Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China;School of Civil Engineering,Xi’an University of Architecture and Technology,Xi’an,Shaanxi 710055,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第4期1358-1367,共10页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.51708016
No.51774018)
中国博士后科学基金项目(No.2017M610755)
北京建筑大学科学研究基金项目(No.KYJJ2017006)
973国家重点基础研究发展计划(No.2015CB0578005)~~
关键词
岩石力学
细观机制
三轴压缩
剪切特性演化
损伤
rock mechanics
micro-mechanism
triaxial compression
variable shear properties
damage
