水合物的存在和分解对能源土的抗剪强度有双面影响。为了研究水合物对于海洋土抗剪强度的影响,考虑到水合物的存在增大了土颗粒之间的接触面积,引入胶结面积比的概念,采用理论推导的方法,修正了考虑水合物影响的有效应力表达式,并提出能够同时考虑水合物种类以及赋存模式的黏聚力表达式。根据摩尔-库伦准则,得到抗剪强度随着水合物饱和度变化的关系式。此外,考虑甲烷气体的溶解,修正了水合物分解后的孔隙压力表达式。最后,借助于沉积物三轴剪切试验和水合物分解的数值模拟结果来验证公式的合理性。结果表明:所提公式能较好地反映水合物含量、水合物赋存状态、高水压对强度的影响;同时修正孔压模型有助于更好地分析海底斜坡稳定。
Abstract
The existence and decomposition of hydrates have two-sided effects on the shear strength of marine energy soil. To investigate the effect of hydrate on the strength of marine energy soil, an expression of the cohesion of marine energy soil is proposed in consideration of the type and occurrence mode of hydrate. As the presence of hydrates increases the contact area between soil particles, the concept of cemented area ratio is introduced to revise the expression of effective stress on account of the influence of hydrate via theoretical derivation. Based on the Mohr-Coulomb criterion, the relation of shear strength varying with hydrate saturation is obtained. In addition, the expression of pore pressure after hydrate decomposition is deduced considering the dissolution of methane gas. The rationality of the proposed expression is verified through triaxial shear test of sediments and numerical simulation of hydrate decomposition. The results conclude that the present expression well reflects the impacts of hydrate content, hydrate occurrence state, and high water-pressure on the strength of marine energy soil; meanwhile, the corrected pore pressure model is helpful to better analyze the stability of submarine slope.
关键词
深海能源土 /
水合物 /
有效应力 /
黏聚力 /
抗剪强度 /
超孔隙压力
Key words
deep sea energy soil /
hydrate /
effective stress /
cohesion /
shear strength /
excess pore pressure
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参考文献
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基金
国家自然科学基金项目(51774018);长江学者和创新团队发展计划项目(IRT_17R06)
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