不同应力路径及围压下煤岩损伤能量演化

Study on Damage Energy Evolution of Coal Rock Under Different Stress Paths and Circumferential Pressures

为研究煤岩体损伤演化过程中能量的转化机制,以王庄煤矿9105工作面原煤为研究对象,利用HC-SPT-100型高压三轴试验机、HC-U7型非金属超声波探测仪、4K科研相机等仪器,采用非接触式数字图像处理技术开展了不同应力路径及围压下三轴加载试验.研究结果表明:(1)不同应力路径及围压下三轴加载过程中煤岩损伤能量演化可分为压密、弹性与脆性跌落3个阶段;(2)试件在不同加载路径与不同初始围压下各阶段能量值相差较大,表现为在同一初始围压下,常规三轴加载路径下试件的弹性能、耗散能、总能量均大于三轴循环加载路径下试件的弹性能、耗散能、总能量;(3)三轴加载过程中,不同加载路径下试件轴向应变从压密到破坏阶段表现为整体波动与局部集中→局部集中→局部集中→整体波动与局部集中的发展规律;(4)不同加载路径及围压下破坏阶段试件的应力集中不同,常规三轴加载路径下破坏阶段试件的应力集中在低围压下以新生应力集中为主、高围压下以继承应力集中为主,三轴循环加载路径下破坏阶段试件的应力集中在高、低围压下主要以继承应力集中为主.

In order to study the transformation mechanism of energy in the process of damage evolution of coal and rock body,triaxial loading tests are carried out for the raw coal of 9105 working face in Wangzhuang coal mine under different stress paths and peripheral pressures,using HC-SPT-100 high-pressure triaxial tester,HC-U7 non-metallic ultrasonic detector,4K scientific research camera and other instruments,and adopting the non-contact digital image processing technology.The results show that:(1)the energy evolution of coal rock damage during the triaxial loading under different stress paths and circumferential pressures can be divided into three stages:compression,elasticity and brittle fall;(2)the energies of the specimens vary significantly in different loading paths and under different initial circumferential pressures,which means that the elastic,dissipative and total energies of the specimens under the conventional triaxial loading paths are greater than the corresponding energies of the specimens under the triaxial cyclic loading paths for the same initial circumferential pressures;(3)during the triaxial loading process,the axial strain of the specimen under different loading paths exhibits evolution of overall fluctuation and localization→localization→localization→overall fluctuation and localization in the densification-to-destruction stage;(4)the stress concentration in the destructive stage of the specimen is different in different loading paths and peripheral pressures.Under the conventional triaxial loading path,the stress concentration mainly takes on the newborn type under the low peripheral pressure,and inherited type under the high peripheral pressure,while under the triaxial cyclic loading paths the stress concentration is mainly the inherited type for both low and high peripheral pressures.