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应力响应包络是本构模型切线刚度的一种几何表达,也是研究本构模型定性特征的有效工具。针对亚弹性、弹塑性及亚塑性等3种类型的土体本构模型,分别以邓肯模型、剑桥模型和Gudehus-Bauer模型为例,讨论了相应的应力响应包络形态,并比较了3类模型各自的特点。并且,通过分析不同模型的应力响应包络及其在主应力空间中的变化规律,说明了亚弹性模型用于模拟土体的加、卸载存在着本质缺陷;弹塑性模型在屈服面附近的中性变载和卸载响应存在一定的问题;亚塑性模型描述的土体切线模量随应变增量方向连续变化的特征比较合理,但简单亚塑性模型难以准确模拟土体不排水剪切应力路径。
Stress response envelope is a geometric expression of the tangent stiffness of the constitutive model, and it is also an effective tool to study the qualitative features of the constitutive model. According to the constitutive models of soil elasticity, elasto-plasticity and sub-plasticity, the Duncan model, the Cambridge model and the Gudehus-Bauer model are taken as examples to discuss the corresponding stress response envelopes. Three types of soil constitutive models are compared, The characteristics of the model. And by analyzing the stress response envelopes of different models and their variation in the main stress space, it is demonstrated that the elastic-plastic model has the essential defects in loading and unloading the soil. The elastic-plastic model near the yield surface There are some problems in the response of loading and unloading. The characteristics of tangential modulus of soil changing continuously with the increment of strain increment are reasonable. However, it is difficult to simulate the undrained shear stress path of soil with simple plastic model.