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赋存于海底沉积物中的天然气水合物与固体颗粒相互胶结,增加了沉积物的强度,一旦水合物分解,会引起沉积物剪切强度降低,如果在含有水合物层上面或附近存在桩基础,必然影响其稳定性。本文采用应力释放法,通过数值计算,分别讨论了桩基础底部位于含水合物地层不同深度时,水合物分解对桩基础应力和变形的影响规律。计算结果表明,随着水合物分解过程中的模量软化和强度衰减,桩基础的水平和竖向位移增大,由于地基水平,土体没有驱动剪应力,水平位移增加不大,地基和桩基础主要表现为竖向沉降;桩底部位于水合物层中间的桩基础的沉降变形,比桩底穿过水合物层的桩基础大,在桩基础及其附近的土体产生较大的应力。
The gas hydrate and solid particles that are present in the seabed sediments bond with each other and increase the strength of the sediments. Once the hydrates dissociate, they cause a decrease in the shear strength of the sediments. If there is a pile foundation on or near the layer containing hydrates , Will inevitably affect its stability. In this paper, by stress relaxation method, the influence of hydrate decomposition on the stress and deformation of pile foundation is discussed respectively by numerical calculation and when the bottom of pile foundation is located at different depths of hydrate formation. The calculated results show that the horizontal and vertical displacements of the pile foundation increase with the modulus softening and strength decay in the process of hydrate decomposition. Because the foundation does not drive the shear stress and the horizontal displacement does not increase much, The foundation is mainly vertical settlement. The settlement of the pile foundation located at the bottom of the pile at the middle of the hydrate layer is larger than the pile foundation penetrating through the hydrate layer at the bottom of the pile. Large stress is generated on the pile foundation and its nearby soil mass.