The stability of methane hydrate depends on not only temperature and pressure but also the salinity of the environment where the methane hydrate exists. The variation in the stability of methane hydrate due to the change in salinity induces mechanical response in micro scale of the methane hydrate-bearing sediments (MHBS). However, it is really heard to quantitatively analyze this effect by controlling salinity of the MHBS in micro scale experiment. Therefore, our study applies Distinct Element Method to investigate the micro-scale mechanical response subject to the salinity variation. An existing contact model for cemented soils is extended to explicitly include the effects of salinity on bond strength and modulus, which are verified by experimental data. Using the proposed thermo-hydro-mechanical-chemical contact model, we conducted a series of case studies to investigate macroscopic and microscopic mechanical responses during three different stress paths, i.e. isotropic, triaxial and constant stress ratio tests. The results show that as the salinity increases, the shear strength and stiffness decrease while the deformation and bond breakage ratio accelerate. The results are valuable to develop constitutive models for MHBS and have safe exploitation of MH resources in the future.

甲烷水合物的稳定性不仅取决于温度和压力，而且取决于甲烷水合物存在的环境的盐度。由于盐度变化而引起的甲烷水合物稳定性的变化在含甲烷水合物的沉积物（MHBS）的微观尺度上引起了机械响应。但是，在微尺度实验中通过控制MHBS的盐度定量分析这种影响确实是听说过的。因此，我们的研究应用离散元方法研究了盐度变化引起的微观力学响应。扩展了现有的水泥土接触模型，以明确包括盐度对粘结强度和模量的影响，并通过实验数据进行了验证。使用建议的热－水－机械－化学接触模型，我们进行了一系列案例研究，以研究三种不同应力路径（即各向同性，三轴和恒定应力比测试）下的宏观和微观机械响应。结果表明，随着盐度的增加，剪切强度和刚度减小，而变形和粘结破坏率加快。这些结果对于开发MHBS的本构模型和在将来安全地开发MH资源具有重要的价值。