State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University

为研究起伏角和法向刚度对结构面剪切力学特性的影响，利用自主研发的煤岩剪切−渗流耦合试验系统，开展了常法向刚度(CNS)条件下人工结构面的直剪试验。结果表明：当起伏角为15°和30°时，剪切应力呈现周期性震荡衰减趋势，在剪切结束时，随着法向刚度的增加，峰值剪切应力的降低量分别是1.78、1.42、1.36和1.27 MPa，逐渐减小。当起伏角为45°时，在剪切应力达到峰值后逐渐趋于残余强度；法向位移演化和剪切应力具有一一对应关系。随着起伏角的增加，剪切刚度逐渐增加。随着法向刚度的增加，起伏角15°和45°结构面的峰值剪切应力基本上线性增加；当起伏角为30°时，峰值剪切应力呈现出分段函数的特征，但是峰值剪胀角却逐渐降低。通过分析剪切前后结构面的质量损失、碎屑粒径占比和三维形貌参数演化得到结构面的破坏模式，当起伏角为15°和45°时，破坏模式较为单一，分别为磨损破坏和切齿破坏；当起伏角为30°时，其破坏模式对试验条件的依赖性较强较为复杂，主要为齿尖剪断破坏和全切齿破坏。通过将结构面三维空间点云数据和对应剪切位移处的法向位移值相结合的方法，得到特定剪切位移处的结构面隙宽演化云图，从而分析结构面在剪切过程中的动态演化过程，得到其破坏机理。

To study the influence of asperity angle and normal stiffness on the shear mechanical properties of the structural plane, a direct shear test of the artificial structural plane with constant normal stiffness (CNS) was carried out using the self-developed coal rock shear seepage coupling test system. The results show that the shear stress presents a periodic oscillation attenuation trend when the asperity angles are 15° and 30°. At the end of shearing, the reduction in peak shear stress with the increase of normal stiffness is 1.78, 1.42, 1.36 and 1.27 MPa, respectively, which is gradually decreasing. While the asperity angle is 45°, the shear stress gradually tends to residual strength after reaching the peak shear stress, and there is a one-to-one correspondence between normal displacement evolution and shear stress. With the increase of the asperity angles, the shear stiffness increases gradually. With the increase of normal stiffness, the peak shear stress of structural planes with 15° and 45° asperity angles increases linearly, and when the asperity angle is 30°, it presents the characteristic of piecewise function, but the peak shear dilatancy angle gradually decreases. The failure mode of the structural plane is obtained by analyzing the mass loss before and after shearing, the proportion of debris particle size, and the evolution of three-dimensional morphology parameters. When the fluctuation angles are 15° and 45°, the failure modes are relatively single, namely wear failure and tooth cutting failure. When the fluctuation angle is 30°, the failure mode has a strong and complex dependence on the experimental conditions, mainly including tooth tip shear failure and full tooth cutting failure. By combining the three-dimensional spatial point cloud data of the structural plane with the normal displacement values at the corresponding shear displacement, a simulated cloud map of the structural plane gap width at a specific shear displacement is obtained, which analyzes the dynamic evolution process of the structural plane during the shear process and obtains its failure mechanism.

国家自然科学基金面上资助项目(51874055，52074047，52274147)

焦峰，许江，彭守建，等. 常法向刚度条件下人工结构面剪切力学特性及损伤演化规律试验研究[J]. 煤炭学报，2023，48(11)：4065−4077.

JIAO Feng，XU Jiang，PENG Shoujian，et al. Experimental study on shear mechanical properties and damage evolution ofartificial structural plane under constant normal stiffness[J]. Journal of China Coal Society，2023，48(11)：4065−4077.