椭圆-抛物线双屈服面模型参数灵敏度分析

利用两种土石料三轴CD试验数据确定两组椭圆-抛物双屈服面模型参数，研究了模型参数? 、KG、n、h、m、M1、M2和pr分别单独变化（而其他参数保持不变）对模型所反映的土的应力-应变关系的影响。结果表明，土体的体积应变对参数h、m比较敏感；? 、KG、n对剪胀性土的体变影响较大，而对剪缩性土体变影响不明显；? 、KG、n、h和m对模型反映的强度没有影响；pr变化对体变和强度影响均较小。M1和M2对强度和体变均有显著影响，且M1和M2中的小值决定模型的强度。定义了灵敏度，即一种用于表示模型参数对其所反映的应力-应变的影响程度的参数。分析表明，不同的参数，其灵敏度差异很大；不同的土类，参数灵敏度差异也较大。实际应用时，对灵敏度大的参数取值应特别慎重。

Analysis of parameter sensitivity of ellipse-parabola double yield surface model

Two groups of parameters of ellipse-parabola double yield surface model from consolidated drained triaxial tests are used to study the influences of stress-strain relationship by changing one of parameters ? , KG, n, h, m, M1, M2 and pr (keeping other parameters constant). It is found that the volume strain is evidently sensitive to the parameters of h and m. On the other hand, ? , KG and n have significant influence on the volume strain for a dilative soil but little influence for a compressive soil. Parameters of ?, KG, n, h and m have no influence on shear strength that is reflected by the double yield surface model. The parameter pr has little influence on the volume strain and shear strength. In the opposite, parameters M1 and M2 affect the volume strain and shear strength dramatically; and the smaller one determines the strength in the double yield surface model. A parameter, called sensitivity which reflects the influence of model parameter on the stress-strain relation, is defined. It is found that different parameters give quite different sensitivities; and different soils also result in different sensitivities. It is pointed out that more attention should be paid to the parameters with high sensitivity to stress-strain of soil.