Marine gas hydrate is an important energy source while its extraction may induce environmental problems such as subsea landslide, which is usually challengeable for numerical simulation due to the marine environment with high pressure and the existence of gas hydrate. Smoothed particle hydrodynamics (SPH) is a Lagrangian particle method which is attractive in modeling problems with large deformations and fluid–solid interactions (FSI) for continuum and granular materials. However, the conventional SPH suffers from numerical instability when modeling the soil mechanics with the high confining stress. A mixed SPH is developed in this study to simulate hydrate-bearing sediment with the characteristics of high confining stress. In the mixed SPH model, the conventional SPH is used to discretize the momentum equations, and the kernel gradient correction (KGC) SPH is used to discretize strain and spin rate tensors. In order to consider the effect of hydrate saturation on the strength of soil-hydrate material, an existing linear model is applied into the mixed SPH to define the mechanic parameters of soil-hydrate material. The mixed SPH method is validated by several examples and the obtained numerical results are in close agreement with experimental observations. Finally, the mixed SPH method is used to model landslide of hydrate bearing sediments. The results show that the saturation of hydrate has important impact on the stability of hydrate bearing sediments.

中文翻译：

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用混合平滑粒子流体动力学模拟含水合物沉积物

海洋天然气水合物是一种重要的能源，其提取可能会引发海底滑坡等环境问题，由于海洋高压环境和天然气水合物的存在，通常对数值模拟具有挑战性。平滑粒子流体动力学 (SPH) 是一种拉格朗日粒子方法，它在模拟连续体和颗粒材料的大变形和流固相互作用 (FSI) 问题时很有吸引力。然而，传统的 SPH 在模拟具有高围压的土力学时存在数值不稳定的问题。本研究开发了一种混合SPH来模拟具有高围压特征的含水合物沉积物。在混合 SPH 模型中，常规 SPH 用于离散动量方程，核梯度校正 (KGC) SPH 用于离散应变和自旋速率张量。为了考虑水合物饱和度对土壤水合物材料强度的影响，将现有的线性模型应用到混合SPH中来定义土壤水合物材料的力学参数。混合 SPH 方法通过几个例子进行了验证，得到的数值结果与实验观察非常吻合。最后，混合SPH方法被用于模拟含水合物沉积物的滑坡。结果表明，水合物的饱和度对含水合物沉积物的稳定性有重要影响。将现有的线性模型应用于混合 SPH 以定义土壤水合物材料的力学参数。混合 SPH 方法通过几个例子进行了验证，获得的数值结果与实验观察非常吻合。最后，混合SPH方法被用于模拟含水合物沉积物的滑坡。结果表明，水合物的饱和度对含水合物沉积物的稳定性有重要影响。将现有的线性模型应用于混合 SPH 以定义土壤水合物材料的力学参数。混合 SPH 方法通过几个例子进行了验证，得到的数值结果与实验观察非常吻合。最后，混合SPH方法被用于模拟含水合物沉积物的滑坡。结果表明，水合物的饱和度对含水合物沉积物的稳定性有重要影响。