初始应力各向异性的边界面方程

由于初始应力状态的非对称性，土体的边界面形状不应该像剑桥模型那样是关于平均球应力轴对称的．根据土体受力后将发生剪切和压缩2部分组合变形的现象分别给出由摩擦引起和由体积压缩引起的塑性功，引入塑性功权系数C，以塑性能量平衡方程为基础，导出了初始应力状态非对称条件下的边界面方程．通过与试验结果的对比分析，得到土体受压时塑性功中摩擦为主和拉伸时体积塑性功为主的规律．并提出确定权系数的初步建议．

Bounding surface equation of initial stress anisotropy

Since the initial stress state in a soil is non-symmetrical,the shape of the bounding surface of the soil is not symmetrical about the axis of the mean normal stress in p-q space,unlike that in the Cam-clay model. The plastic works induced respectively by the volumetric and deviatoric (frictional) deformations are defined in this paper. A weighted coefficient C is introduced to derive the bounding surface equation of the soil under non-symmetrical initial stress condition,based on the equilibrium equation of plastic energy. By comparing the calculated results with the experimental results,it has been found that friction and volumetric plastic work are the main theme in contraction and extension of the soil respectively. Suggestions for determining the weighted coefficient are also proposed.