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为研究交叉双裂隙岩体在剪切过程中的力学响应机制,利用颗粒流程序PFC2D模拟了含交叉双裂隙试样直剪试验,分析了次裂隙倾角和法向应力对交叉双裂隙试样剪切应力、破坏模式、微裂纹发育及演化、能量转化和接触法向方位角演化规律的影响。试验结果表明,法向应力为1、5、15 MPa时,试样破坏受主次2条裂隙的共同控制,大部分交叉双裂隙试样剪切峰值强度高于单一裂隙试样;法向应力为30 MPa时,试样破坏主要受主裂隙影响,表现为各试样强度相近,由于微裂纹扩展速度不均致使剪应力曲线在峰后呈“台阶”状;剪切过程中,裂隙试样所做边界功和黏结能与峰值强度具有相同的变化趋势,裂隙周围颗粒接触矢量方向向剪切方向发生显著偏转。研究成果有助于理解双裂隙岩体在剪切过程中的力学响应机制,是对双隙岩体力学行为研究的补充。
In order to study the mechanical response mechanism of the cross-fractured rock mass during shearing, the direct shear test of the cross-fractured double-fractured specimen was simulated by the particle flow program PFC2D. The effects of the secondary shear stress and normal stress on the cross-double- Shear stress, failure modes, development and evolution of microcracks, energy transformation and the law of contact azimuth evolution. The experimental results show that the specimen failure under the normal stress of 1, 5 and 15 MPa is controlled by the second and second cracks, and the shear peak strength of most of the specimens with cross and double cracks is higher than that of a single fracture specimen. The normal stress At 30 MPa, the failure of the specimen was mainly influenced by the main fracture, which showed that the strength of each specimen was similar, and the shear stress curve was “stepping” after the peak due to the uneven propagation speed of the microcracks. During the shear process, The boundary work and bond energy made by the sample have the same trend with the peak intensity, and the direction of particle contact vector around the fracture is significantly deflected to the shear direction. The research results help to understand the mechanical response mechanism of double-fractured rock mass during shearing, which is complementary to the study of mechanical behavior of double-gap rock mass.