单轴及双轴加载下含裂隙岩石的破裂行为研究

Rupture Behavior of Fractured Rock under Uniaxial and Biaxial Loading

摘要: 探索在工程力作用下岩石裂隙的起裂扩展行为及裂隙岩体的强度变形特性是极其必要的。本文针对含预制双裂隙的立方体岩石试样开展单轴及双轴加载试验，基于DIC岩石表面应变场演化、声发射振铃计数及声发射事件时间间隔函数对单轴、双轴加载下裂隙岩石的破裂行为进行研究，结果表明：(1) 声发射事件率函数可以很好地表征岩石的破坏过程，其能提供相较于声发射振铃计数更多的信息；(2) 加载过程中，裂隙岩石表现出较强的渐进破裂特性，峰后阶段轴向承载能力缓慢丧失，相对于单轴加载，双轴加载下裂隙岩石试样的峰值强度增加9.6%；(3) 相对于单轴加载，双轴加载下试样破坏后相对更完整，主要宏观破裂面减少，这是由于横向围压约束抑制了破裂面的产生。

Abstract: Exploration in engineering force under the action of rock fracture crack propagation and the strength of the fractured rock mass deformation characteristics is very necessary. In this paper, uniaxial and biaxial loading tests are carried out on cubic rock samples with prefabricated double fractures. This study investigates the rupture behavior of fractured rocks under uniaxial and biaxial loading based on the evolution of surface strain fields using Digital Image Correlation (DIC), acoustic emission ring count, and the inter-event time function of acoustic emission events. The results show that: (1) the acoustic emission event rate function can well characterize the failure process of rock and can provide more information than the acoustic emission ringing count. (2) During the loading process, fractured rocks exhibit strong progressive fracture characteristics, with a slow loss of axial bearing capacity in the post peak stage. Compared to uniaxial loading, the peak strength of the two types of fractured rock samples under biaxial loading increased by 9.6%. (3) Compared with uniaxial loading, the sample under biaxial loading is relatively more complete after failure, and the main macroscopic fracture surface is reduced, which is because the lateral confining pressure constraints inhibit the generation of the fracture surface.