中文摘要：

通过含甲烷水合物松散沉积物三轴测试,首次基于临界状态原理探讨水合物沉积物发生应变软化、硬化破坏形式的机制,重点分析各强度参数变化规律及其对破坏模式的敏感性。结果表明：三轴剪切试验过程中沉积物破坏模式受有效围压、水合物饱和度等因素共同控制;破坏模式对峰值强度、起始屈服强度、起始屈服模量、内聚力、内摩擦角等参数的影响较小;不同破坏模式条件下水合物沉积物切线模量、峰值剪切模量等参数变化规律完全不同,其计算模型须在不同破坏模式框架内分别分析,而不能忽略破坏模式的影响建立笼统的水合物沉积物强度参数计算模型。

英文摘要：

In this study,triaxial shear tests were carried out for the defor^nation and failure behaviors of unconsolidated sedi-ments bearing with methane hydrate at different saturations. The principle of critical state theory w,as applied to explore the mechanisms of strain softening and hardening failures. The effects of confining pressure and hydrate saturation on the strength of the hydrate bearing sediment and their sensitivity on the failure mode were investigated. The results show that the failure mode of the sediment is mainly dependent on the effective confining pressure and hydrate saturation, while the effect of the failure mode on the peak strength,initial yielding strength,initial yielding modulus,cohesive force and internal friction angle is not important. However,the tangent modulus and peak shear modulus can be significantly affected by the failure mode. Therefore, the strength parameters of methane hydrate-bearing unconsolidated sediment should be modeled and calculated un-der the same failure mode.