土石混合体单轴压缩试验的三维颗粒流数值模拟

为探究不同含石量土石混合体在单轴压缩荷载下的变形破坏机理,在不规则颗粒三维离散元精细建模技术的基础上,提出了一种不规则块石三维离散元模型随机生成技术,并建立了符合宏观统计规律的土石混合体三维颗粒流数值模型。进行了低、中、高不同含石量(0,10%,30%,50%,70%,90%)的土石混合体单轴压缩试验颗粒流数值模拟,获得了各种含石量的土石混合体在单轴压缩荷载下的应力应变特征和变形破坏特征,并对其变形破坏的细观机理进行了深入的分析探讨。结果表明:随着含石量的增加,土石混合体试样单轴抗压强度和弹性模量随之减小;中低含石量(0,10%,30%,50%)土石混合体的应力-应变曲线表现出典型的应变软化特征,而高含石量(70%,90%)土石混合体在达到峰值应力后表现出一定程度的塑性流动特征;中低含石量土石混合体试样中形成的微裂纹主要是张拉裂纹,宏观上表现出来的是拉裂破坏,而高含石量土石混合体试样中微裂纹很少,主要是剪切裂纹,宏观上表现出来的是剪切破坏。

Three-Dimensional Particle Flow Simulation of Uniaxial Compression Tests on Soil-rock Mixture

In order to study the deformation failure mechanism of soil-rock mixture under uniaxial compression in the presence of different rock block proportions,on the basis of the refined method for constructing discret element method(DEM) model of irregularly shaped particles, a random technique to constructing DEM model of irregularly shaped rock block is proposed and 3-D particle flow models of soil-rock mixture which conform to the macroscopic statistical rule are established. Then, particle flow simulations of uniaxial compression tests are conducted. It is noteworthy that with the increment of rock block proportions, the uniaxial compressive strength and the elastic modulus both decrease. Stress-strain curves of soil-rock mixture with medium-low rock block proportions (0, 10%, 30%, 50%) show a typical feature of strain softening; whereas stress-strain curves of soil-rock mixture with high rock block proportions (70%, 90%) show some degree of plastic flow characteristics after peak stress. Micro-cracks in the specimens of SRM with medium-low rock block proportions are mainly tensile cracks, resulting in macroscopic tensile rupture; while few micro-cracks develop in the specimens of soil-rock mixture with high rock block proportions, which are mainly shear cracks, resulting in macroscopic shear failure.