块石空间定向性对土石混合体力学性质的影响

Effects of Rock Block Orientation on the Mechanical Characteristics of Rock and Soil Aggregate

土石混合体作为一种土和石的特殊混合体,其宏观变形破坏及力学性质与块石的空间定向性密切相关。为了研究块石定向性对土石混合体变形破坏机理的影响,采用二维颗粒流软件中FISH语言编写算法生成不同角度的椭圆形块石,建立土石混合体二维颗粒流数值模型,分别进行了单块石和多块石条件下土石混合体双轴试验数值模拟,对其变形破坏机理进行了深入分析。结果表明:块石角度不同时,土体中裂纹萌生位置不同;随着块石短轴方向与最大主压力轴夹角增大,土石混合体黏聚力先减小后增加,内摩擦逐渐减小;在应力峰值前的应力平缓增长阶段,土体中裂纹迅速增长,在试样强度达到峰值后进入残余强度阶段,裂纹的增速也逐渐降低;块石角度不同时,土石混合体的剪切带破坏形式不同。

Rock and soil aggregate(RSA)is a complex mixture of soil and rock,and its macroscopic deformation and mechanical characteristics are closely related to the spatial distribution of rocks.To study the deformation and failure mechanism of RSA with different directional distributions of rock blocks,a two-dimensional numerical RSA model was constructed using the FISH language in the particle flow code(PFC).Different directions of oval shaped rock blocks were generated and,then,numerical simulation of biaxial compression tests were conducted with single rock block and multi rock blocks,followed by a discussion of the deformation and failure mechanism.Results indicated that the location of crack initiation in the soil was different when the angle of rock blocks were different.With the increase of the degree between rock blocks’ short axis and the direction of minimum principal pressure axis,the cohesion of the RSA decreased firstly and then increased,and the angle of internal friction decreased gradually.The crack in soil increased rapidly at the stage of gentle stress growth before reaching the peak strength,while the increase rate decreased gradually when the residual strength was reached.The pattern of shear failure zone was often different if the degree between rock blocks’ long axis and the maximum principal pressure axis are different.