为研究土的复杂的变形机理 ,采用适用于不连续体问题的数值分析方法—— DDA (discontinuous deform ationanalysis)对土的平面应变试验进行了模拟。结合对颗粒间相互作用的理论分析揭示了土的弹塑性、剪胀性、应变软化、卸载 -再加载时的滞回圈、卸载体缩以及剪切带的形成等独特的应力变形现象和特性的微观机理。试验结果与数值模拟的对比表明 ,这是一种研究土的本构关系的强有力的工具 In order to study the complex deformation mechanism of soil, the plane strain test of soil was simulated by using the numerical analysis method applied to discontinuity problem (DDA). Combined with the theoretical analysis of the interaction between particles, the unique stress deformation phenomena and characteristics of soil such as elasto-plasticity, dilatancy, strain softening, hysteresis loop during unloading-reloading, unloading shrinkage and formation of shear band are revealed The micro-mechanism. A comparison of experimental results with numerical simulations shows that this is a powerful tool for studying the constitutive relationship of soils