含水承载煤岩损伤演化过程能量释放规律及关键孕灾声发射信号拾取

不同含水状态对煤岩样损伤演化过程有重要的影响,为了研究不同含水状态煤岩样单轴压缩全过程煤岩样损伤演化过程能量释放规律,并基于能量贡献率与振铃计数贡献率共同准则拾取关键孕灾声发射信号,以指导声发射技术在岩体工程监测和灾害预警中的应用。利用岩石力学试验系统和全信息声发射信息分析仪,开展不同含水状态煤岩样的单轴压缩试验,主要对不同含水状态下煤岩样的力学特性、能量释放规律、破坏模式以及关键部位孕灾声发射信号进行拾取。试验结果表明,不同含水状态煤岩样力学性质各不相同,含水率的增大能有效弱化煤岩样强度。不同含水状态煤岩样能量释放规律各不相同,水在软化煤岩基质的同时,也对弹性应变能进行大量吸收,进一步导致含水煤岩受载屈服阶段弹性应变能占比增大,耗散应变能迅速降低,对应蓄能期(声发射平静期),待其孔隙水压力增大到对裂隙进行了扩展与贯通,即试样马上进入破坏阶段。不同含水状态下煤岩样单轴压缩破坏模式均为剪切形式,且含水率增大,剪切裂纹趋于复杂。同时验证了基于能量贡献率和振铃计数贡献率计算准则的声发射信号拾取方法可行,并与其他常规声发射参数形成对应关系,可为具体分析前兆特征分析和灾变预警提供参考。

Energy release law during the damage evolution of water-bearing coal and rock and pick-up of AE signals of key pregnancy disasters

Water-bearing state has an important influence on the damage evolution process of coal and rock samples.In order to study the l energy release law in the whole process of damage evolution of coal and rock samples with different water-bearing states under uniaxial compression,to pick up the AE signals of key pregnancy disasters based on the common criteria of energy contribution rate and ringing count contribution rate and hence to guide the application of AE technology in rock mass engineering monitoring and disaster early warning,uniaxial compression tests of coal and rock samples in different water-bearing states are carried out by using rock mechanics test system and full-information AE information analyzer.The mechanical properties,energy release law,failure modes and key parts of disaster AE signals of coal and rock samples under different water-bearing conditions are mainly analyzed.The test results show that the mechanical properties of coal and rock samples are different in different water-bearing states and the increase of water content can effectively weaken the strength of coal and rock samples.The energy release law of coal and rock samples in different water-bearing states is different.While water softens the coal-rock matrix,it also absorbs a large amount of elastic strain energy,which further leads to an increase of the proportion of the elastic strain energy and a rapid decrease of the dissipative strain energy in the loading yield stage of water-bearing coal and rock corresponding to the energy storage period(AE quiet period).When the pore water pressure increases to expand and penetrate the cracks,the sample immediately enters the failure stage.Under different water-bearing conditions,the uniaxial compression failure modes of coal and rock samples are in the form of shear,and the shear crack tends to be complex as the water content increases.The AE signal picking method based on the energy contribution rate and ring count contribution rate calculation criterion is verified to be feasible,and a corresponding relationship with other conventional AE parameters is established.The research results can provide reference for the specific analysis of precursory characteristics and disaster early warning.