水合物赋存模式对含水合物土力学特性的影响

INFLUENCE OF OCCURRENCE MODE OF HYDRATE ON MECHANICAL BEHAVIOUR OF HYDRATE-BEARING SOILS

基于非饱和制样法(US法)和饱和试样气体扩散制样(SD法)2种制样方法,利用三轴剪切试验研究不同水合物赋存模式对含CO2水合物土力学特性的影响规律。试验结果证实水合物的赋存模式及其含量对含水合物土的力学特性存在重要影响,微观机制分析表明:US法制得试样属于胶结赋存模式,该模式表现出典型的胶结土的结构特性,而SD法制得试样根据水合物含量不同,属于填充模式、接触模式和透镜体模式,显示出明显的颗粒摩擦材料的力学特性,但由于水合物的破碎损伤效应也会导致应变软化现象。最后,利用有效水合物饱和度的概念,提出能考虑2种水合物形成模式下抗剪强度预测的经验公式。

Based on the two synthesis methods of hydrate in soils,the unsaturation sampling(US method) and gas diffusion sampling method for saturation soil(SD method),triaxial shear tests are performed to study the effects of occurrence mode of hydrate on the mechanical properties of hydrate-bearing soils containing CO2. The experimental results confirm that the occurrence mode and saturation of hydrate have significant impact on the mechanical behaviour of soil with hydrate. In view of the microscopic mechanism,some analysis indicate that samples formed by US method,which are called as cementation mode,exhibit some structure characteristics of cementing soil. the samples formed by SD method,which are called as pore filling mode,loading mode and lenticle mode,show the properties of the friction material significantly,and exhibit strain softening due to the crushing damage of hydrate during the shearing period. Besides,by introducing a new parameter-the effective saturation of hydrate,a formula considering the influence of hydrate synthesis methods,which can predict the shearing strength of hydate-bearing soil,is proposed.