Granite is often encountered in underground engineering, and its mechanical properties and failure behavior directly determine its stability and seepage characteristics. Unlike other rocks, granite is usually considered heterogeneous. Based on the Weibull distribution, this paper proposes a novel modeling method for heterogeneous granite via the combined finite-discrete element method (FDEM), and the mechanical properties and failure behavior of granite under uniaxial and triaxial compression, Brazilian splitting, and direct tension, as well as the influence of the loading rate, were investigated. The research results indicate that (1) the new modeling method can be used to construct a heterogeneous granite numerical model that includes three types of randomness (mineral spatial distribution randomness, mineral size randomness, and mineral shape randomness) and can quantitatively change the mineral composition; (2) uniaxial and triaxial compression simulation tests reveal that as the content of weak minerals (biotite) increases, the uniaxial compressive strength and equivalent cohesion decrease as a power function, and Young's modulus decreases as a linear function, while the equivalent internal friction angle decreases as an exponential function; (3) heterogeneous granite exhibits different mechanical properties and failure behaviors under Brazilian splitting and direct tension due to their different failure modes; typically, the tensile strength obtained from direct tension testing is lower than the value obtained from Brazilian splitting testing; and (4) as the loading rate increases, the strength, stiffness, and number of cracks of the specimen first stabilize and then increase as a power function, with a critical rate of =1 m/s.

中文翻译：

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非均质花岗岩的力学性能和破坏行为：基于威布尔的新 FDEM 数值模型的见解


花岗岩在地下工程中经常遇到，其力学性能和破坏行为直接决定其稳定性和渗流特性。与其他岩石不同，花岗岩通常被认为是异质的。基于威布尔分布，本文提出了一种新颖的异质花岗岩联合有限离散元法（FDEM）建模方法，研究了花岗岩在单轴和三轴压缩、巴西劈裂和直接拉伸作用下的力学性能和破坏行为，以及加载速率的影响进行了研究。研究结果表明：（1）新的建模方法可以构建包含三种随机性（矿物空间分布随机性、矿物尺寸随机性和矿物形状随机性）并能定量改变矿物成分的非均质花岗岩数值模型。 ; (2)单轴和三轴压缩模拟试验表明，随着弱矿物(黑云母)含量的增加，单轴抗压强度和等效内聚力呈幂函数下降，杨氏模量呈线性函数下降，而等效内摩擦角作为指数函数减小； (3)异质花岗岩由于破坏模式不同，在巴西劈裂和直接拉力作用下表现出不同的力学性能和破坏行为；通常，直接拉伸试验获得的拉伸强度低于巴西劈裂试验获得的值； (4)随着加载速率的增加，试件的强度、刚度和裂纹数量先稳定后呈幂函数增加，临界速率=1 m/s。