摘要
针对硬岩的脆性破坏问题,利用真三轴和声发射(AE)试验系统研究了灰岩试样在不同应力路径和应力水平下的力学特征与变形破坏机理、AE活动特征及能量释放规律。试验研究表明:(1)开挖卸荷应力路径下,试样强度受卸荷作用影响较大,且随中间主应力呈区间性变化,试样以脆性劈裂破坏为主;(2)开挖卸荷+支护的应力路径下,支护力显著改善了岩石的力学性质,破坏形式以张剪性破坏为主;(3)试样AE活动过程可以分为三个活跃期(裂隙压密阶段、卸荷阶段和失稳-破坏阶段)和两个相对平静期(弹性变形阶段和微破裂稳定发展阶段),AE信号表征参数"absolute energy"作为能量度量指标能够较好地定量描述和研究硬岩的脆性破坏过程。试验结果和许多工程开挖和支护过程中岩体的力学行为和支护作用类似,可为工程现场开挖支护设计提供试验依据和有益指导。
Aiming at brittle failure of hard rock(taking limestone for example),true triaxial and acoustic emission experiments are adopted to study the mechanical characteristics,deformation and failure mechanisms,characteristics of acoustic emission(AE)activities and law of energy release.The experimental results indicate:(1)Under the unloading stress path,strength of specimens is apparently effected by unloading,and varies in intervals along with the intermediate principal stress.Failure modes of most specimens are splitting.(2)Under the unloading-supporting stress path,the mechanical properties of rock are significantly improved by supporting force.The main failure mode is tensile shear failure.(3)The whole process of AE activity can be divided into 3 active stages(crevasse crack closing stage,unloading damage stage and destruction stage)and 2 relatively quiescence stages(elastic stage and fracture stable development stage).The characterization parameter"absolute energy"of AE can quantitatively describe the brittle failure of hard rock.The results of experiments are similar with rock mass behaviors and support effect in project field so as to provide test basis and guide instruction for engineering practice.
作者
向天兵
冯夏庭
陈炳瑞
江权
XIANG Tian-bing;FENG Xia-ting;CHEN Bing-rui;JIANG Quan(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2008年第S01期500-506,共7页
Rock and Soil Mechanics
基金
国家高技术研究发展计划(863计划)项目(No.2006AA06Z117)
国家自然科学基金委员会、二滩水电开发有限责任公司雅砻江水电开发联合研究基金项目(No.50539090)。
关键词
岩石力学
脆性破坏
真三轴试验
岩石声发射
应力路径
rock mechanics
brittle failure
true triaxial experiment
acoustic emission of rock
stress path
