含水合物土抗拉强度特性

TENSILE STRENGTH CHARACTERISTICS OF HYDRATE-BEARING SOIL

含水合物土的抗拉强度特性对含水合物地层的稳定评估具有重要意义。以黏质粉土为赋存介质,利用四氢呋喃(THF)合成含水合物土试样,在冷冻库中利用改进后的单轴拉伸装置研究了含水合物土单轴抗拉强度特性。试验结果表明水合物饱和度、试样干密度、细粒含量对含水合物土的抗拉强度存在明显影响。随着水合物饱和度的增加,抗拉强度呈现指数函数的增长趋势。干密度和细粒含量对抗拉强度的影响在不同的水合物饱和度情况下影响不同,在低水合物饱和度情况下,干密度和细粒含量的增加会使抗拉强度增强;而在较高的水合物饱和度情况下,抗拉强度则随着干密度和细粒含量增加而降低。此外,通过分析含水合物土的波速特性,建立抗拉强度与波速之间的经验关系式。这一关系式对采用声波来估算含水合物土试样的抗拉特性具有重要的参考意义。

The tensile strength characteristic of hydrate-bearing soil is important for evaluating the stability of hydrate-bearing layer during hydrate exploitation.Adopting the clayey silt as host sediment,the hydrate-bearing soils were synthesized by using tetrahydrofuran(THF)instead of methane.Meanwhile,the tension tests were performed in controlled temperature environment.The results show that when hydrate saturation,dry density and content of fine grain have significant influences on the tension strength.As hydrate saturation increases,the tension strength exhibits an increase tendency with exponential function.The influences of dry density and fine grain content are related with the hydrate saturation.At the low hydrate saturation,the increase in dry density and fine grain content can improve the tensile strength.At the high hydrate saturation,the tensile strength lowers with the increasing dry density and fine grain content.In addition,the acoustic wave for hydrate-bearing soil is measured.The relationship between tensile strength and acoustic wave characteristic is analyzed,which is useful for estimating the tensile strength of hydrate-bearing soil in the future.