对UE土体动力本构模型的修正

Correction of Unsymmetrical Exponential DynamicConstitutive Model of Soil

摘要:

动力本构模型UE模型具有可以描述非对称循环荷载、记忆量小、模型参数物理意义明确、表达式简单等优点。但其描述等幅循环荷载作用下的土体滞回圈时，存在非对称性，并且无法较好地拟合土体动阻尼比随应变产生的变化规律。通过在UE模型的骨架曲线中引入两个瞬变参数，利用“massing二倍法”构造滞回曲线，使模型同时满足各个应变下的剪切模量及阻尼比，确定瞬变参数的表达式，将瞬变参数表达式带入滞回曲线方程中，即得到最终的滞回曲线表达式，并定义各个滞回圈顶点的连线为此修正模型的实际骨架曲线。分析结果表明，该修正模型能够克服UE模型存在的不足，且更符合实际。

Abstract:

The unsymmetrical exponential （UE）dynamic constitutive model is used to describe the soil characteristics under dynamic loading.This model has the advantages of describing asymmetric cyclic loading，low memorization，explicit physical meanings of the model parameters，and simple expressions. However，the UE model is asymmetric and is unable to appropriately fit the distribution of soil damping ratio variation with changing strain when it is used to describe the soil hysteresis loop under constant amplitude cyclic loading.By introducing two transient variable parameters in the skeleton curve of the UE model and using Massing’s method of doubling the stress and strain variables to structure the hysteretic curve，the correction model can accurately determine the shear modulus and damping ratio under different strains.The shear modulus and damping ratio were then used determine the expression of the transient parameter, and they were substituted in the hysteretic curve equation. Finally，the hysteretic curve expression and the actual skeleton curve were obtained.The results show that the correction model can overcome the limitations of the UE model and is in good agreement with the actual data.