中砂侧向变形特性的真三轴试验研究

Lateral Deformation Characteristic of Medium Sand by True Triaxial Test

保持小主应力、中主应力不变，在大主应力方向加荷是实际工程中可能存在的一种应力路径，该应力路径分别对粉砂、细砂和中砂进行了几组真三轴试验。针对中砂的真三轴试验结果，对其应力应变关系及反映侧向变形变化规律的泊松比进行了特定条件下的研究，结果表明，在特定的应力路径下排水剪切，小主应力方向膨胀，泊松比可以大于０ ．５ 甚至大于１ ，中主应力方向首先压缩，之后膨胀，泊松比可以小于０，这是现代土力学和有限元分析中不曾考虑的现象和结果。

Keeping minor principle stress and medium principle stress fixed and loading in the direction of maxinum principle stress is a potential stress path in practical projects under which several groups of true triaxial tests about silt,fine sand,medium sand are studied.The true triaxial test results of medium sand indi cate that Poisson's ratio can be greater than 0.5 so far as to l in the direction of minor principle stress,and less than 0 in the direction of medium principle stress.These phenomena and results have not been considered in modern soil mechanics and finite element method analysis.