基于广义塑性理论的尾砂本构模型在ABAQUS中的二次开发

建立尾砂的本构模型是开展尾矿坝数值模拟和安全评价的重要基础，而目前尾砂的本构模型研究多集中于非线性弹性模型，如Duncan-Chang模型，关于弹塑性模型的研究较少。结合尾砂的应力-应变特性，提出了一种适用于描述尾砂力学特性的改进广义塑性模型。基于用户自定义材料子程序UMAT，将提出的模型在ABAQUS中二次开发实现，应力积分采用Runge-Kutta显式积分。通过三轴试验模拟验证，偏差应力曲线表明，有限元计算结果可以反映围压对应力-应变关系的影响，抗剪强度随应变逐渐硬化，达到峰值强度，随后发生应变软化，抗剪强度有所下降。体应变曲线结果表明，广义塑性模型可以很好地描述体应变曲线的体缩-体胀发展过程，与试验曲线吻合较好。同时有限元数值模拟结果和理论值误差很小，且和试验结果拟合较好。该研究成果可进一步用于尾矿坝的应力变形计算和安全评价。

Secondary development of a constitutive model in ABAQUS for tailings sand using generalized plasticity theory

Constitutive model of tailings sand plays an important role in the numerical simulation and security evaluation of tailings dam. However, current researches focus on nonlinear elastic model such as Duncan-Chang model, but less on elastoplastic model. A modified generalized plasticity model considering the stress-strain property of tailings sand is proposed to describe the mechanical characteristics of tailings sand. The constitutive model is developed in ABAQUS with user defined material subroutine UMAT and explicit stress integration of Runge-Kutta method. Finally, the modified model is verified in ABAQUS by triaxial test simulation. The deviatoric stress curve shows that the results of finite element method can reflect the influence of confining pressure on stress-strain relationship. And the shear strength gradually increases with strain increases, followed by strain softening after reaching the peak strength. Volumetric strain calculation results show that the generalized plasticity model can well describe the volumetric strain development, which is in good agreement with the experimental curve. Meanwhile, finite element computation data match well with test data, and the theoretical value. The research results can be further used in the stress-strain analysis and security evaluation of tailings dam.