Gas hydrate-bearing sediments (GHBS) are considered a significant potential energy source. However, the decomposition of hydrates can lead to various geological hazards. Therefore, a comprehensive investigation into the mechanical properties of GHBS is essential to ensure the safe extraction of gas hydrate. This paper presents a constitutive model for GHBS that incorporates anisotropy, based on the theory of thermodynamics. To account for the effects of hydrate filling and cementing, two parameters are introduced into the dissipation function of the model. The filling effect is expressed through the densification mechanism, which increases the density of the host sediment. The cementing effect is represented by the enhanced expansion of the yield surface. The yield function incorporates the spacing ratio $r$ and the teardrop shape parameter $\alpha$, which govern the shape of the yield surface, as well as the anisotropy angle ${𝜃}_n$, which signifies the anisotropic evolution law. The physical significance of these parameters is also elucidated. The anisotropic evolution is described by an exponential function. The proposed model is compared to both the test results and the existing constitutive model, and it is found that it provides more accurate predictions of the mechanical properties of GHBS.

含有天然气水合物的沉积物（GHBS）被认为是一种重要的潜在能源。然而，水合物的分解会导致各种地质灾害。因此，对GHBS的力学性能进行全面研究对于确保天然气水合物的安全开采至关重要。本文基于热力学理论，提出了一种包含各向异性的 GHBS 本构模型。为了考虑水合物充填和固井的影响，模型的耗散函数中引入了两个参数。充填效应通过致密化机制来表达，致密化机制增加了宿主沉积物的密度。胶结作用表现为屈服面的扩张增强。屈服函数包含间距比$r$和泪滴形状参数$\alpha$，它控制屈服面的形状以及各向异性角${𝜃}_n$，表示各向异性演化规律。还阐明了这些参数的物理意义。各向异性演化由指数函数描述。将所提出的模型与测试结果和现有本构模型进行比较，发现它可以更准确地预测 GHBS 的力学性能。