Based on the stress redistribution analysis of rock mass during the deep underground excavation, the unloading process of pre-flawed rock material was simulated by distinct element method (DEM). The effects of unloading rate and flaw inclination angle on unloading strengths and cracking properties of pre-flawed rock specimens are numerically revealed. The results indicate that the unloading failure strength of pre-flawed specimen exhibits a power-function increase trend with the increase of unloading period. Moreover, combined with the stress state analysis on the flaws, it is found that the unloading failure strength increases with the increase of flaw inclination angle. The cracking distribution of pre-flawed specimens under the unloading condition closely depends on the flaw inclination angle, and three typical types of flaw coalescence are observed. Furthermore, at a faster unloading rate, the pre-flawed specimen experiences a sharper and quicker unloading failure process, resulting in more splitting cracks in the specimens.%基于深部开挖过程中的应力重分布分析,利用离散元方法(DEM)对卸载过程进行模拟,揭示卸载条件下卸载速度和裂隙倾角对含裂隙岩体的强度和裂纹特性的影响.结果表明:随着卸载周期的增大,含裂隙岩体的卸载破坏强度呈幂函数增大.同时,结合缺陷上的应力分析发现,含裂隙岩体的卸载破坏强度随着裂隙倾角的增大逐渐增大;卸载条件下含裂隙岩体的裂纹分布主要取决于裂隙倾角,并总结了3种不同的裂隙搭接方式;此外,卸载速度越快,含裂隙岩体的卸载破坏过程越剧烈,岩体内部形成的劈裂裂纹越多.
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