红砂岩单轴压缩条件下震源时空演化特征及破裂机制实验研究

Experimental study on the characteristics of the temporal and spatial evolution of the source and the rupture mechanism of red sandstone under uniaxial compression

为建立岩石工程灾害精准预测预报体系,本文进行了红砂岩试件震源时空演化特征及破裂机制实验研究。采用单轴加载方式,以声发射技术和数字散斑相关方法进行实验数据的采集,基于矩张量反演方法,分析岩石变形局部化带相对位移速率和震源体积参数、裂纹能量的对应关系,探讨岩石破裂机制及前兆特征。研究结果表明:(1)岩石承载力受变形局部化结构演化控制,变形局部化带的变形集中是引起岩石应力-应变曲线非线性演化的主要原因;(2)声发射信息与岩石的拉伸和错动变形具有相关性,当变形局部化带相对拉伸和错动位移速率突增时,声发射裂纹体积参数和对应破裂类型的裂纹能量随之发生突增;(3)在裂纹错动阶段,变形局部化带相对拉伸和错动位移速率曲线幅值突增后,对应的张拉和剪切破裂占比上升;(4)微裂纹发育以混合破裂为主,在裂纹发生扩展、交汇和贯通时,裂隙的位错运动以剪切和张拉裂纹为主。

In order to establish an accurate prediction and forecasting system for rock engineering disasters,experimental studies on the temporal and spatial evolution characteristics and failure mechanism of red sandstone test sources have been carried out.The uniaxial loading method is used to collect experimental data combined with the acoustic emission technology and the digital speckle correlation method.The moment tensor inversion method is used to analyze the relationship between the relative displacement rate of the rock deformation localization zone and the source volume parameters and crack energy,and to explore the rock failure mechanism and precursor characteristics.The results show that:(1)The rock bearing capacity is controlled by the deformation localization structure evolution,and the deformation concentration of the deformation localization zone is the main reason for the nonlinear evolution of the stress-strain curve of the rock;(2)The acoustic emission information of rock is correlated with the change of the relative displacement rate of the deformation localization zone.When the relative extension and the dislocation displacement rate of the deformation localization zone suddenly increase,the acoustic emission crack volume parameter and the crack energy corresponding to the rupture type increase suddenly;(3)After the amplitudes of the relative tension and displacement rate curves of the deformation localization zone increase suddenly,the proportion of the corresponding tension and shear fracture increases;(4)The development of microcracks is dominated by the mixed rupture.When the cracks propagate,meet and penetrate,the dislocation movement of the cracks is dominated by the shear and tension cracks.