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.