基于颗粒离散元的土石混合体强度影响研究

土石混合体是一种具有复杂结构的非连续介质，其细观结构对强度特性具有重要影响。基于随机生成多边形块体技术，生成土石混合体概念模型，引入形状系数衡量块石凹凸程度。通过东岭信滑坡堆积体室内试验标定颗粒流数值模拟的细观参数，开展双轴试验模拟，研究块石凹凸性、块石分布倾角、边界条件和含石量4种因素对土石混合体强度特性的影响，探讨块石形状的凹凸性对土石混合体强度产生影响的主要原因。结果显示：块石凹凸程度和含石量越大，块石之间容易相互接触咬合，形成稳定的受力骨架，导致强度提高；块石的分布倾角对强度特性亦有较大影响，在不考虑块石破损时，块石长轴与主应力方向平行或垂直时试样强度较大，块石长轴与主应力方向斜交时强度较小；边界效应随着试样尺寸的增大，对模拟结果的影响逐渐减弱。

Research on strength of soil-rock mixture based on particle discrete element method

 Soil-rock mixture is a kind of discontinuous media, whose mesostructure has a major impact on the strength characteristics. The conceptual model of soil-rock mixture is formed by using the technique of randomly generating polygon block. The shape coefficient is introduced as an index to measure the concave and convex degree of the block stone. The appropriate parameters are selected for the simulation by the laboratory test method of Donglingxin deposit. The influence of rock concavity, rock inclination and boundary conditions on the strength characteristics of soil-rock mixtures is studied by numerical biaxial test. The results show that the greater the degree of concavity and stone content, the easier the rocks contact with each other. Thus a stable skeleton will be formed and lead to an increase in strength. If the effect of rock breaking on the simulation results is ignored, when the long axis of the block stone is parallel or perpendicular to the direction of the principal stress, the strength of the specimen is larger, while when the long axis of the block stone is oblique to the direction of the principal stress, the strength of the specimen is smaller. With the increase of specimen size, the influence of boundary effect on simulation results decreases.