某砂土液化大变形本构模型参数的敏感性分析

Sensitivity analysis of model parameters for predicting liquefied large deformation of sand

基于Yang和Ahmed[1-5]等提出的砂土液化大变形本构模型,对该模型的硬化规则和弹塑性模量确定方法作了改进,把该本构模型扩展应用到三维液化大变形的数值分析中,实现了基于ABAQUS大型商用软件计算平台上砂土液化大变形的计算子程序开发。基于该计算平台,对该模型的主要参数在描述砂土液化动孔隙水压力增长和动应力-应变关系曲线等方面的可靠性和敏感性进行了研究。给出了模型全过程参数、剪胀过程参数、剪缩与剪胀状态转换点流动变形量控制参数对试样的应力-应变关系曲线的影响程度及其规律,并对模型的主要参数的敏感性进行了分析,所得结论为通过动三轴试验获得相关模型参数提供了有效的指导和帮助,同时也发展了砂土液化大变形新的数值计算方法。

Based on the constitutive equations given by Yang and Ahmed et al. to predict the liquefied large deformation of sand, the hardening rule of model and the calculation method of elastoplastic modulus are modified. Then, it is extended to 3-D equations and is implemented by using Fortran subroutine program and is implanted into ABAQUS finite-element software. By using ABAQUS software with the advanced model, how the main model parameters to affect the dynamic pore pressures arising and the stress-strain curves of sand, are analyzed in detail, respectively. At the same time, the sensitivities of model parameters are also analyzed. It is proved that the subroutine program can work perfectly to model the liquefied large deformation of sand; and the combination of different model parameters＇ values can predict perfectly the different deformation stage of sand. These conclusions verified and given here can be used expediently to fixed the model parameters by using dynamic triaxial tests. Accordingly, a new effectively numerical method used to calculate the large liquefaction is advanced by using the advanced finite-element ABAQUS software with special constitutive model.