为深入认识土体的变形与破坏规律和合理设计土体的承载能力 ,根据密砂的三轴试验数据 ,建立了反映土的应变软化的弹塑性模型。用有限元法对密砂的厚壁筒内压扩张问题进行了计算 ,结果表明密砂的厚壁筒的内压扩张问题具有整体软化和突然崩塌式的破坏特性 ,说明所建立的应变软化模型有较好的适用性 In order to understand deeply the law of deformation and failure of soils and to design the bearing capacity of soils reasonably, according to the triaxial test data of sand, the elastic-plastic model to reflect soil softening is established. The finite element method was used to calculate the pressure expansion in the thick-walled cylinder of sand. The results show that the internal pressure expansion of the thick-walled cylinder with sand has the characteristics of overall softening and sudden collapse, indicating that the strain softening model Has good applicability