摘要
为研究冷热交变岩石的力学性能和损伤演变规律,对冷热交变后的花岗岩进行单轴压缩试验和巴西劈裂试验,利用声发射监测和电镜扫描技术分析花岗岩加载过程中的声发射信号特征和试样破坏后的微观形态特征。结果表明,在不同冷热交变次数下,花岗岩的抗压强度与抗拉强度都明显降低,且两者呈显著的线性关系。在单轴压缩条件下,花岗岩的破坏模式以轴向劈裂破坏和剪切破坏为主;在巴西劈裂条件下,随着热处理温度的升高,花岗岩的破坏表现为径向破坏、径向弧形破坏和沿弱结构平面的混合破坏。两种实验条件下试样破坏过程中的声发射计数变化与应力−应变曲线变化基本一致。归一化累积声发射计数可以较好地反映试样加载过程中的损伤演变特征。试样的初始损伤随着温度和冷热交变次数的增加而增加,导致花岗岩在加载过程中的损伤率持续增长。此外,基于力学参数定义了三个损伤变量,其中基于抗拉强度的损伤变量对冷热交变次数最为敏感。
To explore the static mechanical and damage evolution characteristics of hot dry rock,groups of uniaxial compression test and Brazilian splitting test were performed on granite after cyclic heating-cooling treatment.Acoustic emission(AE)monitoring and scanning electron microscopy(SEM)techniques were utilized to analyze the AE characteristics and the micro-morphological characteristics of granite samples.The results show that the compressive strength has a significant linear relationship with the related tensile strength of the granite after different heating-cooling cycles.In both tests,the changes in AE counts basically agree with those in stress−strain curves.The normalized accumulated AE counts can well reflect the damage evolutions during complete loading of the granite.The initial damage to the granite increases with increasing temperature and number of heating-cooling cycles,resulting in a constant increase in the rate of damage to the granite.In addition,three damage variables were defined,of which the damage variable based on the tensile strength is the most sensitive to the number of heating-cooling cycles.
作者
彭康
任基
王元民
罗松
龙坤
PENG Kang;REN Ji;WANG Yuan-min;LUO Song;LONG Kun(School of Resources and Safety Engineering,Central South University,Changsha 410083,China;State Key Laboratory of Green and Low-carbon Development of Tar-rich Coal in Western China,Xi’an University of Technology,Xi’an 710048,China;School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China)
基金
Project(2023YFC2907400)supported by the National Key Research and Development Program of China−2023 Key Special Project
Project(SKLCRKF1908)supported by the Open Fund of the State Key Laboratory of Coal Resources in Western China,Xi’an University of Science and Technology
Project(51974043)supported by the National Natural Science Foundation of China
Project(2023JJ10072)supported by the Hunan Provincial Natural Science Foundation for Distinguished Young Scholars,China
Project(2022RC1173)supported by the Science and Technology Innovation Program of Hunan Province,China。
关键词
单轴压缩
巴西劈裂
岩石损伤
声发射
扫描电镜
冷热交变
uniaxial compression
Brazilian splitting
rock damage
acoustic emission
scanning electron microscopy
heating-cooling cycles
