胶结土石混合体力学特性的块石形状效应细观机理分析

考虑块石形状为球体、正方体和长方体三种情况,通过正方体与球体相比较来探究块石不同棱角度对胶结土石混合体力学特性的影响,通过长方体与正方体相比较来探究块石不同球度对胶结土石混合体力学特性的影响.首先,基于不规则颗粒三维离散元精细模拟技术实现了正方体和长方体块石数值模型的建立;然后建立含石量为30%和80%的块石形状分别为球体、正方体和长方体的胶结土石混合体三维离散元随机结构模型;最后,对土石混合体大三轴试验进行颗粒流数值模拟,获得了不同含石量、不同块石形状下胶结土石混合体的强度特征和变形特征,并分别就低、高两种含石量下块石形状对土石混合体力学特性影响的细观机理进行了深入地分析.结果表明:块石含量和形状均会显著影响胶结土石混合体的力学特性,并且两者间具有复杂的交互作用;微裂纹、块石颗粒平均旋转量、应变能和摩擦功等的演化规律能够很好地从细观水平上反映块石形状影响的作用机理.

Analysis on meso-mechanisms of influence of rock block shape on mechanical properties of cemented soil-rock mixture

In order to explore the meso-mechanisms of influence of rock block shape on mechanical properties of cemented soil-rock mixture (SRM), Spherical, cubic and cuboid-shaped rock blocks are taken into consideration. SRM with cubic rock blocks are compared with that with spherical rock blocks to explore the influence of block angularity. SRM with cuboid-shaped rock blocks are compared with that with cubic rock blocks to explore the influence of block sphericity. Firstly, numerical models of cubic and cuboid-shaped rock blocks are constructed based on a 3-D DEM refined modeling technology for irregularly shaped particles. Then, 3-D DEM stochastic models of cemented SRM with 30% and 80% rock block proportion (RBP) are established, whose block shape is spherical, cubic and cuboid-shaped respectively. Then, a particle flow simulation of large scale triaxial tests of SRM is conducted to obtain strength and deformation characteristics of SRM with different rock block shape and RBP. Finally, Meso-mechanisms of influence of rock block shape on mechanical properties of cemented SRM with low and high RBP is intensively analyzed. The results show that RBP and rock block shape both significantly affect the mechanical behaviors of SRM and there is complicated interaction of the two factors. The evolution of micro-crack, mean rotation of rock blocks, strain energy and frictional work can well reflect the meso-mechanisms of influence of rock block shape.