考虑围压影响的盐岩弹塑性损伤本构模型研究

深入研究盐岩受力变形、破坏机制及力学模型,对于保证油气地下储库的安全和稳定具有十分重要的意义。以盐岩在多组围压下的三轴试验为基础,由热力学定律出发,将损伤引入到改进的摩尔-库仑(Mohr-Coulomb)准则中,提出了与围压相关的损伤准则和塑性硬化函数,建立了一种能够描述盐岩力学特性的弹塑性损伤模型,该模型能够反映盐岩的塑性与损伤耦合、应变硬化-软化和围压影响。将研究成果与ABAQUS软件相结合,通过二次开发,编制了相应的计算程序。通过模拟盐岩室内三轴压缩试验表明,数值模拟曲线与试验曲线吻合较好,所建立的力学模型可以较好地描述盐岩在不同围压状态下的力学损伤发展、应变硬化-软化以及脆-塑性转换的力学特征。

An elastoplastic damage constitutive model for salt rock considering confining pressure effect

Further study of the mechanism and law of salt rock deformation and breakage has great significance for the safety and stability of the gas storage. Based on the triaxial compression test under different confining pressures, a new elastoplastic damage model with improved Mohr-Coulomb criterion is presented in the framework of the irreversible thermodynamics and nonlinear continuum mechanics, which can depict the confining pressure effect, hardening and softening behaviours of salt rock. In this model, the mechanical damage criterion and hardening function highly depend on the stress state. The solution process for the coupled model is studied using finite element method and the corresponding computer code is developed on the ABAQUS solver. The numerical simulation under various stress states shows that the numerical simulations perfectly agree with the experimental data; and the proposed model is able to effectively depict the main features of mechanical behaviors of salt rock.