能源土边界面模型的应力更新算法及算例分析

The stress update algorithm of bounding surface model on gas hydrate-bearing soil and case study

水合物的存在会显著影响能源土的刚度、峰值强度与剪胀性。针对已有能源土模型的不足,结合边界面模型的建模思想,构建一个新的能源土边界面模型,模型参数较少,能够恰当反映能源土的应力-应变关系。计算能源土变形问题的核心在于正确积分塑性本构方程,应用完全隐式回退Euler算法,建立模型应力及塑性内变量的更新公式,并给出显式的一致性切线模量表达式。基于ABAQUS软件提供的二次开发接口,编写模型的用户材料子程序,应用已有试验数据验证程序正确性。最后应用开发的子程序对能源土的平面应变试验进行模拟,分析水合物饱和度对剪切带倾角与孔隙比的影响。

The existence of gas hydrate can significantly affect the stiffness,peak strength and dilatancy of gas hydrate-bearing soil(GHBS).Aiming at the deficiency of the existing models,a bounding surface model of GHBS was constructed.The presented model has fewer parameters and can precisely reflect the behavior of GHBS.The key of calculating the deformation of GHBS lies in the correct integration of constitutive equations.Using the fully implicit back Euler algorithm,the integration algorithm of bounding surface model and the consistent tangent matrix are derived.Based on the redevelopment interface provided by ABAQUS software,the user material subroutine of the model is written,and the correctness of the program is verified.Finally,a series of plane strain tests of GHBS are simulated by using the developed subroutine,and the effect of hydrate saturation on shear band inclination and void ratio is analyzed.