针对含水合物沉积物基础力学试验数据相对缺乏的现状,分别采用通气法和预冻结法制备了含甲烷水合物和含四氢呋喃(THF)水合物的砂性沉积物试样,并通过低温高压三轴试验系统研究了含水合物沉积物的强度特性及其影响因素,重点分析了试样强度在不同水合物饱和度情况下的发展规律,并证实了试验反压的重要影响。结果表明:试样黏聚强度随水合物饱和度增加呈指数型增长。当水合物饱和度不高时(〈50%),试样内摩擦角变化不大;当饱和度较高时(〉80%),由于土颗粒咬合作用不能充分发挥,试样内摩擦角降低。另外,反压有助于提高水合物强度,从而提高含水合物沉积物的强度。
Due to the scarcity of basic data of hydrate-bearing sediments,a series of triaxial tests are made on synthetic samples of methane-hydrate-bearing and tetrahydrofuran-hydrate-bearing sandy sediments,which are generated using the gas-filtration method and the pre-freezing method,respectively.Attention is focused on the bulk strength of the specimens at different levels of hydrate saturation.The contribution attributed to the back pressure is confirmed by use of the experimental data.The results indicate that the cohesion exponentially increases with the increase of the hydrate saturation.No significant variation is found in the internal frictional angle of the specimens with low to medium hydrate saturation(50%),while the angle decreases with the increase of the hydrate saturation due to less particle interlocking at high saturation(80%).In addition,the back pressure helps to strengthen the hydrate in voids and thus causes an increase in the strength of the hydrate-bearing specimens.