Abstract Natural gas hydrate in marine sediments and permafrost areas is considered as an important potential energy source. Since hydrate dissociation will reduce the stability of gas hydrate-bearing sediments (GHBS) and may cause wellbore failures and geological disasters during gas production, it is necessary to reveal the mechanical behavior of GHBS for the safe exploitation of natural gas hydrate. This paper proposes a geomechanical constitutive model of GHBS within the multishear bounding surface framework. Following the slip theory of plasticity, a constitutive formulation is obtained by splitting the macro constitutive response of sediments into a macro volume response and a series of micro shear responses in spatial distributions related to virtual microshear structures. Each microshear structure describes micro shear and dilatancy responses in three orthogonal orientations. A micro stress–strain relationship and a micro stress–dilatancy relationship are established for each orientation of the microshear structure. The model comprehensively describes the consolidation, hardening, softening, dilatation, collapse, and non-coaxial characteristics of gas hydrate-bearing sediments by introducing the multishear concept, state parameter, evolution law of hydrate bonding and debonding, and collapse strain caused by hydrate dissociation. The effectiveness of the model is confirmed by simulating the available published laboratory tests on the samples of synthetic and natural GHBS under different pore pressures, temperatures, initial void ratios, hydrate saturations, and initial effective confining stresses.

中文翻译：

---

含天然气水合物沉积物的地质力学本构模型，基于状态相关的多剪切边界面模型

摘要 海洋沉积物和多年冻土区的天然气水合物被认为是一种重要的潜在能源。由于水合物分解会降低含天然气水合物沉积物（GHBS）的稳定性，并可能导致天然气生产过程中的井筒失效和地质灾害，因此有必要揭示GHBS的力学行为，以保证天然气水合物的安全开采。本文提出了多剪切边界面框架内的 GHBS 地质力学本构模型。遵循塑性滑动理论，通过将沉积物的宏观本构响应分解为宏观体积响应和一系列与虚拟微剪切结构相关的空间分布中的微剪切响应，得到本构公式。每个微剪切结构描述了三个正交方向的微剪切和剪胀响应。微剪切结构的每个方向都建立了微应力-应变关系和微应力-剪胀关系。该模型通过引入多剪切概念、状态参数、水合物成键和解键演化规律以及水合物解离引起的坍塌应变，综合描述了含天然气水合物沉积物的固结、硬化、软化、膨胀、坍塌和非共轴特征。 . 通过在不同孔隙压力、温度、初始孔隙比、水合物饱和度和初始有效围压下模拟合成和天然 GHBS 样品的可用实验室测试，证实了该模型的有效性。