水合物分解对桩基础应力和变形影响的研究

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。

Study on Stress and Deformation of Pile Foundation due to Methane Hydrate Dissociation

Methane hydrate in submarine sediment works as a cementing material that bonds solid grains, and makes the sediment stronger.Once the hydrate dissociates,it will cause the reduction of shear strength in sediment.If the pile foundation is laid in the hydrate layer or near it,the stability will be affected. In this paper,the stress release method is used to study the strain and stress properties of pile foundation caused by the hydrate dissociation when the pile is laid in differert layers.The results show that the horizontal and vertical displacements will increase with the modulus softening and strength reduction after hydrate dissociation.Because the ground is horizontal and there is no shearing strength,the horizontal displacement is small.There is mainly vertical displacement in the ground and pile foundation.As the pile bearing capacity changes differently,the vertial settlement of pile in the middle of the hydrate layer is larger than that through the hydrate layer.The stress increases greatly in the pile foundation and around the soil.