矿物颗粒形状的岩石力学特性效应分析

岩石作为矿物颗粒的集合体，其宏观力学特性主要影响因素为矿物的细观形态特征。基于颗粒流理论，建立了4种代表颗粒形状用于模拟石英砂岩的矿物颗粒，并采用球度指标对矿物颗粒形状进行参数量化。通过石英砂岩的室内三轴试验校准了颗粒流模型的细观参数，在此基础上进行四种矿物颗粒形状试样的岩石三轴力学模拟试验。研究结果表明：颗粒的球度越大，试样的启裂强度、损伤强度和峰值强度均越低。随着颗粒球度的增加，试样的弹模降低，泊松比增大。内摩擦角和黏聚力则随球度的增大而下降。根据岩样数值试验中的变形数据，研究了不同颗粒形状剪胀角随着塑性剪切应变的演化规律。

Mechanical behaviors of rock affected by mineral particle shapes

The effect of mineral microstructure on macroscopic mechanical behaviors of rock as aggregates of mineral particles is remarkable. Four representative particles based on the basic theories of particle flow code are created to simulate the mineral particles in quartz sandstone. Then, sphericity is used as a particle shape factor to quantify the particle shapes. With the aid of triaxial compression tests on quartz sandstone, calibration of model parameters is performed. Then triaxial tests are performed on four kinds of rock samples formed by different particle shapes. The results show that the crack initiation stress, crack damage stress, and peak stress of samples decrease with the rising sphericity. Increasing sphericity leads to smaller elastic modulus and larger poisson ratio. And decreasing sphericity results in higher cohesion and internal friction angle. As for the rock samples made of different particle shapes, the evolvement laws of dilatancy angle with plasticity parameter are studied.