中文摘要：

适用性较好的土体模型除了能较好地模拟土体的应力-应变关系外,还应该能较好地反映土体的侧向变形,即合理计算广义泊松比。在椭圆-抛物双屈服面模型的基础上,建立了反映侧向变形特性的广义泊松比公式,并利用广义泊松比来研究砂-聚苯乙烯颗粒轻质填料的变形规律。文中研究了包括材料配比在内的主要参数对广义泊松比的影响,发现与剪胀有关的参数对广义泊松比的影响较大。基于砂-聚苯乙烯颗粒轻质填料的三轴固结排水剪切试验数据,给出了相关模型参数,结合该材料的剪切强度、变形特性与建立的广义泊松比公式,对该泊松比能否恰当反映土体的变形特性（剪缩、剪胀和侧向变形）进行验证,结果表明广义泊松比可以反映土体的变形特性,尤其是侧向应变及体积应变规律。

英文摘要：

A well established constitutive model not only confidently simulates the stress-strain characteristics of geomaterials,but also properly reflects the lateral deformation of geomaterials;specifically,the generalized Poisson’s ratio shall be reliably figured out by using the constitutive model.Based on elliptic-parabolic yield surfaces model,a generalized Poisson’s ratio was derived to reflect the characteristics of geomaterials’ lateral deformation characteristics.Effects of main model parameters on the magnitude of Poisson’s ratio were analyzed.Parameters associated with dilatancy were found clearly affecting the generalized Poisson’s ratio.Based on the results of consolidated-drained triaxial shear tests of sand-expanded polystyrene（EPS） lightweight fills,verification was conducted with respect to the elliptic-parabolic yield surfaces model and the generalized Poisson’s ratio.It is shown that the model largely simulated the stress-strain characteristics of fills,so did the generalized Poisson’s ratio on describing fills’ deformation behavior,i.e.dilatancy,contraction and lateral deformation.