不同类型砂岩基于多物理场监测的损伤特征与裂纹演化特性研究

Study on damage characteristics and crack evolution properties of different types of sandstones based on multi-physics field monitoring

摘要

完整岩石与裂纹岩石在循环荷载作用下会产生不同形式的新生裂纹，研究不同类型岩石的裂纹演化过程对于保障岩体结构的安全与稳定具有重要意义。基于声发射、电阻率与DIC监测技术，从声学、电学与光学等多物理场角度监测岩石裂纹的演化过程。研究结果显示：完整岩石在单轴压缩与单轴循环加卸载作用下的峰值强度基本一致，前者的破裂模式为张拉破坏而后者为剪切破坏。预制裂纹岩石在循环荷载作用下的峰值强度随裂纹数量的增多而减小，单、双裂纹岩石的破裂模式均为张拉破坏。在循环过程中，声发射计数从微观角度反映岩石裂纹的萌生状态，其在加载阶段较多而在卸载阶段较少，这表明微裂纹的萌生基本发生加载阶段。岩石电阻率从宏观角度反映岩石裂纹的连通状态，其与岩石应变具有一定的相关关系，即电阻率的峰值对应应变的谷值而电阻率的谷值对应应变峰值。同时，基于DIC监测获取了不同类型岩石的新生裂纹演化过程。基于多种监测角度探究了岩石在循环荷载作用下的裂纹演化过程，对后续研究岩石的损伤特征具有积极意义。

Abstract

Complete rock and cracked rock will produce different forms of new cracks under cyclic loading. It is of great significance to study the crack evolution process of different types of rock to ensure the safety and stability of rock mass structure. Based on acoustic emission(AE), resistivity and DIC monitoring technology, the evolution process of rock cracks is monitored from the perspective of acoustic, electrical and optical multi-physical fields. The results show that the peak strength of intact rock under uniaxial compression is basically the same as that under uniaxial cyclic loading and unloading. The failure mode of the former is tensile failure and the latter is shear failure. The peak strength of pre-cracked rock under cyclic loading decreases with the increase of the number of cracks. The failure mode of single and double crack rock is tensile failure. In the cyclic process, the acoustic emission count reflects the initiation state of rock cracks from a microscopic point of view. It is more in the loading stage and less in the unloading stage, which indicates that the initiation of microcracks basically occurs in the loading stage. Rock resistivity reflects the connectivity state of rock cracks from a macro perspective, which has a certain correlation with rock strain, that is, the peak value of resistivity corresponds to the valley value of strain and the valley value of resistivity corresponds to the peak value of strain. At the same time, the evolution process of new cracks in different types of rocks was obtained based on DIC monitoring. Based on a variety of monitoring angles, the crack evolution process of rock under cyclic loading is explored, which is of positive significance for the subsequent study of rock damage characteristics.

关键词

裂缝岩石 / 裂缝发展 / 电阻率 / 声发射(AE) / 数字图像相关(DIC)

Key words

cracked rock / crack development / resistivity / acoustic emission(AE) / digital image correlation(DIC)

Author summay

江 浩(1982—), 男, 高级工程师, 博士, 从事岩土工程勘察与设计工作。E-mail: [e-mail]

基金资助

国家自然科学基金项目(52279117)