基于直接生成法的土石混合体三维随机模型构建与数值仿真研究

3D stochastic model and numerical simulation of soil-rock mixture based on direct method

通过对土石粒径界限、块石分布规律与粒径分布频度的研究,基于直接生成法建立了土石混合体的三维随机模型,形成了一套较为完整的、操作性强的三维随机模型构建方法。在此基础上,将三维随机模型构建方法与FLAC^(3D)随机建模方法相结合,建立与真实土石混合体具有相同统计规律的有限差分模型,开展室内直剪数值仿真试验研究,获取了不同垂直压力下的剪应力-位移曲线和相应的剪切带分布,探讨了土石混合体的剪切破坏特性与土石相互作用机制。剪切过程中由于土体产生的不同程度的剪切变形以及块石在摩擦作用下发生的水平或旋转运动,导致土石混合体的剪切带表现出明显的不规则和不连续特点,其剪应力-位移曲线具有应变硬化特点。研究表明,三维随机模型能够反映土石混合体的宏观力学性质和细观破坏机制,可作为力学性质研究的有效载体。

From the study of the particle size boundary, rock distribution and particle frequency, a three-dimensional （3D） stochastic model of soil-rock mixture is generated by using the direct method. A set of relatively complete and easily operational method is developed for building the 3D stochastic model. Moreover, a finite-difference model is established with the same distribution as natural soil-rock mixture by combining the newly developed building method and FLAC30 random modeling method. Then, direct shear tests and its numerical simulations are performed to obtain shear stress-displacement curves under different vertical pressures, which is fiLrther applied to explore shear failure characteristics of soil-rock mixture and the interaction mechanism between soil and rock. Due to different levels of shear deformation of soil and the horizontal or rotational motion of stone under the friction action, the shear band of soil-rock mixture shows obviously irregular and discontinuous features in the shear process, and the shear stress-displacement curve exhibits significant strain hardening behavior. This study shows that the 3D stochastic model can be used to well represent macroscopic mechanical properties and microscopic failure mechanisms of soil-rock mixture, which can be served as a model to explore the mechanical property.