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岩石单轴加载破坏全过程波速变化特征研究

Study on variation characteristics of wave velocity in whole process ofrock uniaxial loading failure

  • 摘要: 岩石力学性质是声波监测技术的基础,可通过观测声波在岩石内部传播变化过程判别岩石的稳定性和发育状况。为了解赵庄二号井岩石载荷受力下声波于介质传播过程中变化状况,单轴加载试验采用岩石力学试验机和声波测试系统,对晋城赵庄二号井典型层位的砂岩、泥岩、灰岩加工成标准试样,在单轴加载条件下,采用不同加载方法进行比对,获取方法适用性。然后,利用观测声波对岩石裂隙发育程度、不同岩性的纵、横波波速及应力-应变全过程的变化特征进行了研究。研究结果表明:选用位移控制法可以更好获取全应力-应变曲线;在加载过程中,试样压密、弹性阶段波速呈线性上升的趋势;到达应力峰值后,试样破损,承受力降低并出现软化特征,应力与波速呈非线性变化;波速变化趋势与应力-应变曲线基本一致,不同的应力-应变阶段均发生不同的波速响应特征。通过对岩石加载声波变化特性的测试观察,可对岩体的稳定性或内部裂隙发育程度做出预测预判。

     

    Abstract: Mechanical properties of rock is the basis of the acoustic wave monitoring technology. The stability and development of rocks can be studied by observing the propagation process of sound waves inside the rock. In order to understand the variation of acoustic waves in the medium propagation process under the rock load of No. 2 Zhaozhuang Mine, the uniaxial loading test adopted the rock mechanics experimental machine and the acoustic testing system to test the sandstone, mudstone and limestone of the typical strata of No.2 Zhaozhuang Mine in Jincheng under the condition of uniaxial loading, different loading methods were used to compare and obtain the applicability of the method. Then, the observed acoustic waves were used to study the development of rock fissures, the longitudinal and transverse wave velocities of different lithologies and the changes of stress-strain processes. The test results show that the displacement control method can obtain the full stress-strain curve better. During the loading process, the sample velocity is linear and the wave velocity increases linearly; when the stress peak is reached, the specimen is damaged and the bearing capacity is reduced, the softening characteristics appear, and the stress and the wave velocity change nonlinearly. The variation trend of wave velocity is basically consistent with the stress-strain curve, and different wave velocity response characteristics occur in different stress-strain stages. Through the test observation of the acoustic wave loading characteristics of rock loading, the stability of rock mass or the development of internal fractures can be predicted, which has important guiding significance for the response characteristics analysis of acoustic emission monitoring technology.

     

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