粗粒土组构二维模型试验研究

粗粒土的宏观力学性质取决于粗粒土的初始组构及剪切过程中的组构变化。为研究组构对粗粒土应力应变关系的影响，通过制取不同初始组构的试样，进行了粗粒土二维模型平行试验。应用计算机图像测量系统，对颗粒的运动进行量测，从而获得受力变形过程中组构的变化。通过分析组构与应力应变的关系，得到如下认识①平行试验的粗粒土的应力应变曲线有一定差异，说明组构对应力应变起决定作用;②在试样破坏之前，枝向量和颗粒长轴的定向性随着应力的增长逐渐增强;③峰值偏应力随着枝向量初始组构主值比的增大而增大;④平均枝长随体变的增大而略有减小;⑤平均配位数并未随着孔隙比的减小而增大，可能与模型试验中采用多边形颗粒及颗粒偏少偏大有关。

Two-dimensional Model Tests on Fabric of Coarse-grained Soils

The macro-mechanical properties of coarse-grained soils depend on its initial fabric and fabric variation in deformation process. Specimens of different initial fabric structures were prepared and two-dimensional parallel tests were conducted to investigate the influence of fabric on stress-strain relationship of coarse-grained soils. Particle movement was measured by computer image measure system, and fabric change in deformation process of coarse-grained soils was evaluated. Results show that (1) the stress-strain curves of parallel tests were different, which means fabric plays an important role in stress-strain relationship; (2) the orientations of branch vector and particle’s long axis enhanced with the increase of stress in the shear process before failure happened; (3) the peak deviatoric stresses increased with the increase of principal values of initial fabric; (4) the average branch length decreased slightly with the increasing of volumetric strain; (5) the average coordination number did not increase with the diminish of void ratio, which was probably related with polygon particles and big particles in small numbers.