Gas extraction from methane hydrate reservoirs results in significant changes to pore pressure, causing soil deformation and progressive failure. Current advanced constitutive models, which are capable of capturing this deformation process, are often complex, computationally expensive, and challenging to implement in numerical solvers. Hence, simpler models are generally preferred; however, these models fail to predict critical geomechanical aspects such as strain softening and dilation. To address this limitation, the present study proposes a unified constitutive model based on the disturb state concept (DSC), considering the state variables such as hydrate saturation, temperature, and effective confining pressure for gas hydrate sediments. The stress–strain relationship is derived by combining two distinct responses: a hyperbolic hardening response that extends the stress–strain behavior prior to the peak stress state and a DSC approach to capture the post-peak softening and dilation response. Furthermore, the model is rigorously validated by utilizing multiple sets of triaxial experimental data of gas hydrate sediments under different initial conditions. This comprehensive validation process ensured the robustness and reliability of the proposed model. Finally, the efficacy of the model is analyzed based on the energy absorption capacity and index of agreement approach.

中文翻译：

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结合天然气水合物沉积物应变软化行为的基于扰动状态概念的模型

从甲烷水合物储层中提取气体会导致孔隙压力发生显着变化，导致土壤变形和渐进破坏。目前能够捕获这种变形过程的先进本构模型通常很复杂，计算成本很高，并且在数值求解器中实现起来具有挑战性。因此，通常首选更简单的模型；然而，这些模型无法预测关键的地质力学方面，例如应变软化和膨胀。为了解决这一局限性，本研究提出了一种基于扰动状态概念（DSC）的统一本构模型，考虑了天然气水合物沉积物的水合物饱和度、温度和有效围压等状态变量。应力-应变关系是通过组合两种不同的响应得出的：双曲线硬化响应在峰值应力状态之前扩展应力-应变行为，而 DSC 方法则捕获峰值后软化和膨胀响应。此外，利用多组不同初始条件下天然气水合物沉积物三轴实验数据对模型进行了严格验证。这种全面的验证过程确保了所提出模型的稳健性和可靠性。最后，基于能量吸收能力和一致性指标方法对模型的效果进行了分析。