三点弯曲试验条件下的岩石声发射演化特征  

Acoustic Emission Evolution Characteristics of Rock Under Three-point Bending Tests

作　　者：赵慧子 梁正召 刘祥鑫[3] ZHAO Huizi;LIANG Zhengzhao;LIU Xiangxin(State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,Dalian,Liaoning 116024,China;Center of Rock Instability and Seismicity Research,Dalian University of Technology,Dalian,Liaoning 116024,China;School of Mining Engineering,North China University of Science and Technology,Tangshan,Hebei 063210,China)

机构地区：[1]大连理工大学土木工程学院,海岸和近海工程国家重点实验室,辽宁大连116024 [2]大连理工大学岩石破裂与失稳研究中心,辽宁大连116024 [3]华北理工大学矿业工程学院,河北唐山063210

出　　处：《水利与建筑工程学报》2020年第2期6-12,共7页Journal of Water Resources and Architectural Engineering

基　　金：国家自然科学基金项目(41977219,51779031)。

摘　　要：开展16个辉绿岩试样在三点弯曲加载条件下的声发射试验,得到含有不同切口位置的应力-应变曲线、断裂模式与声发射特征参数,研究在不同拉-剪应力条件下的岩石声发射特性,基于归一化方法研究试样损伤演化规律,运用分形分析方法计算声发射信号的关联维数D,研究不同拉伸与剪切共同作用下试样的分形前兆特征。结果表明:三点弯曲条件下,试样以微破裂为主,发生张拉脆性断裂。随着预制裂纹距离左端支撑距离d的增加,岩石抗弯强度降低,断裂能耗逐渐降低。由声发射参数表征的脆性岩石损伤前兆特征显现时间先后顺序为:事件率前兆时间<振铃计数前兆时间<能量计数前兆时间。随着试样弯曲应力增加,关联维数变化模式呈"降-升-降"的变化规律,与单轴压缩的"波动-持续下降"具有明显不同。关联维数的二次降低预示岩石最终失稳破裂即将发生,可以作为岩石失稳的前兆信息。Stress-strain curves, fracture modes and acoustic emission characteristic parameters of 16 diabase samples containing different notch positions were obtained under three-point bending loading conditions monitored by acoustic emission system to analyze acoustic emission characteristics of rocks under different tensile-shear stress conditions. Based on the normalization method, the damage evolution law of the sample was investigated. The fractal analysis method was used to calculate the correlation dimension D of the acoustic emission signal. The characteristics of the fractal precursor of the sample under the action of different tensile-shear stress were discussed. The results are as follows. Under the three-point bending condition, microcracks dominate and the tensile brittle fracture occurs. As the offset notch distance from the left-end support distance d increases, the bending strength decreases and the fracture energy consumption of the rock gradually decreases. Damage precursor occurrence time characterized by acoustic emission parameters: event rate < ringing count < energy count. As the stress of diabase increases, the correlation dimension changing mode is "down-up-down", which is significantly different from the "fluctuation-continuous descent" of uniaxial compression. The second decrease of correlation dimension indicates that the failure is about to occur, which can be used as precursor information for rock failure.

关 键 词：三点弯曲 分形特征 损伤演化 声发射 前兆信息 

分 类 号：TU453[建筑科学—岩土工程]