含水合物土体的土水特征曲线及渗透系数  

Soil-water characteristic curve and permeability of hydrate-bearing soils

作　　者：颜荣涛[1] 徐玉博 颜梦秋 YAN Rongtao;XU Yubo;YAN Mengqiu(Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学广西岩土力学与工程重点实验室,广西桂林541004

出　　处：《岩土工程学报》2023年第5期921-930,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(11962004);广西科技基地和人才专项(桂科AD20325010)。

摘　　要：含水合物土的土水特征曲线和渗透系数对分析水合物开采效率和地层稳定性具有重要意义。通过自我改造而成的含水合物土的土水特征曲线的测试装置,测试了含水合物土(黏质粉土和砂土)的土水特征曲线,研究了水合物形成对土体的土水特征曲线的影响规律和机理,并且分析了含水合物土体的非饱和状态下的渗透系数。试验结果分析表明:水合物形成对含水合物土体的土水特征曲线存在明显影响;随着水合物饱和度的增长,可以看到边界效应段明显增大,过渡段土水特征曲线变得逐渐平缓,非饱和残余段对于残余水饱和度更低,但是VG模型仍能有效的描述含水合物土的土水特征曲线;进气值随着水合物饱和度的增加而增大,而残余有效水饱和度则随之减小,这主要是由于水合物形成改变了沉积物内部的孔隙孔径分布特征。在非饱和状态下,由于渗流通道被气体挤占,含水合物土的相对渗透系数随毛细吸力增加而减小,但是在同样的毛细吸力下,越大的水合物饱和度对应的相对渗透系数越小。Understanding the soil-water characteristic curve(SWCC)and permeability of hydrate-bearing soils plays a critical role in analyzing the production efficiency and layer stability during hydrate exploitation.Based on the self-improved apparatus,hydrate is formed within clayey silt and sand sediment,and the SWCC of the hydrate-bearing clayey silt and sand is measured.Further,the influence law and mechanism of hydrate formation on the SWCC are investigated,and the permeability of the hydrate-bearing soils at unsaturated state is analyzed.The test results show the hydrate formation has a significant effect on the SWCC of the hydrate-bearing soils.As the hydrate saturation increases,the boundary effect segment remarkably increases,the SWCC changes gently during the transition segment,and the corresponding saturation reduces.However,the VG model is able to address the SWCC of the hydrate-bearing soils.Since the hydrate formation changes the pore-size distribution structure of the hydrate-bearing soils,the gas entry pressure increases but the saturation of the effective residual water decreases with the increasing hydrate saturation.Under the unsaturated state,the relative permeability of the hydrate-bearing soils reduces with the increasing capillary suction as the seepage channel is crowded by gas.At a given capillary suction,the higher hydrate saturation corresponds to the smaller relative permeability.

关 键 词：含水合物土体 THF水合物 土水特征曲线 进气值 残余水饱和度 渗透系数 

分 类 号：TU411[建筑科学—岩土工程]