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土石混合体的抗剪强度在很大程度上取决于其块石的含量、空间分布、形态等参数。该文采用球体单元模拟土颗粒,通过组合颗粒单元构造非规则形态的块石,对不同含石量和块石空间分布下土石混合体的直剪过程进行了离散元数值模拟。计算结果表明,在低含石量下,土石混合体的抗剪强度随含石量的增加而增加;在中含石量下,受块石空间分布的影响,其抗剪强度呈现很强的波动性;在高含石量下,其抗剪强度显著增强,波动性相对较小。抗剪强度在中高含石量下波动现象的细观机理是块石空间分布影响下的力链结构特性。当块石的空间分布使其形成较强力链结构时,抗剪强度较高;反之,块石间的力链结构不稳定,抗剪强度相对较低。以上研究有助于从细观尺度揭示土石混合体变形和剪切强度特性的内在机理。
The shear strength of soil-rock mixture depends greatly on the content, spatial distribution, morphology and other parameters of rock and stone. In this paper, the spherulites are used to simulate the soil particles. By combining the granular units to construct the irregularly shaped rock, the discrete element numerical simulation of the direct shear process of the soil-rock mixture under different stone content and rock mass spatial distribution is carried out. The calculated results show that the shear strength of soil-rock mixture increases with the increase of rock content at low stone content, and the shear strength of stone-rock mixture increases with the stone content under the influence of spatial distribution of rock mass At high contents of rock, the shear strength is significantly increased and the volatility is relatively small. The meso-scale mechanism of the fluctuation of shear strength at medium and high stone content is the structural characteristics of the force chain under the spatial distribution of rock mass. When the spatial distribution of rock mass makes it form stronger chain structure, the shear strength is higher; on the contrary, the chain structure between rock and stone is unstable and the shear strength is relatively low. The above research is helpful to reveal the intrinsic mechanism of the deformation and shear strength characteristics of the rock-soil mixture from the meso-scale.