关键词: 粗粒土, 三轴试验, 颗粒运动, 应力应变关系, 组构, 颗粒破碎, 抗剪强度

Abstract: Coarsegrained soil is the main material constructed in rockfill dams, and the research of mechanics properties is a focus of soil mechanics, which is generally obtained by triaxial test. Particle movement is difficult to observe in triaxial test due to shortcomings of test means. Twodimensional model test for coarse grained soil was designed and carried out in order to get particle movement laws in test process and to research the mesodeformation mechanism of coarsegrained soil. This paper primarily deals with twodimensional tests. Particle movement can be observed clearly in test process, and the deformation characters of specimen can also be analyzed qualitatively. The test results indicate:(1) the peak deviatoric stress increases with the increase of lateral pressure, the soften phenomenon occurs after peak stress, the specimen is compressed at first stage and then dilates, and the dilatancy property decreases with the increases of lateral pressure; (2) the MohrCoulomb failure envelope shows good linear relationship; (3) the particle breakage increases with the increase of lateral pressure, and particle breakage occurs even at very low lateral pressure; (4) the shear zone occurs when the specimen comes to failure. The above laws on stress strain relationship, shear strength, particle breakage and specimen failure mode are in good agreement with the results of triaxial test, which indicates that the model test can reflect triaxial test process.