摘要
天然气水合物完全分解时,产生的气体使得能源土孔隙压力急速增加,有效应力减小,进而引起土体液化破坏。此时深海能源土斜坡的应力状态与静力液化失稳过程可简化为含气土在常剪应力排水(或不排水)应力路径下的破坏问题。以此为背景,提出了制备含气砂土试样的改进充气管法,并开展了含气砂土的常剪应力路径三轴试验。22组试验结果表明:同一孔隙比的含气密砂在不同围压与常剪应力下具有相同的失稳线;含气砂土试样失稳时的应力比和体变均随初始相对密实度的增大而增大;含气密砂在常剪应力路径下饱和度对失稳特征影响的规律性在排水与不排水条件下均不明显,但在不排水条件下含气砂土的孔压(或体变)对变形的敏感性降低;含气密砂在常剪应力路径到达失稳点之后,排水条件下是瞬变的液化鼓胀破坏,不排水条件下是渐变的剪切破坏。
When natural gas hydrate is completely decomposed, the gas generated in this process makes the pore pressure increased rapidly and the effective stress decreases in energy soil, which leads to liquefaction failure of soil. At this time, the stress state and static liquefaction instability of deep sea energy soil slope can be simplified as the failure of gas-bearing soil under a constant shear stress drained or undrained stress path. Based on this, an improved gas tube method is proposed to prepare the gassy sandy soil samples, and a series of triaxial tests with constant shear stress path is carried out. The results of the 22 sets of experiments show that the gassy dense sand with the same void ratio has the same instability line under different cell pressures or different constant shear stress paths. The stress ratio during instability and volume strain increase with the increase of initial relative compactness. The regularity of saturation effect on the instability of gassy dense sand under the constant shear stress path is not obvious in both drained and undrained conditions, but the sensitivity of pore pressure(or volume deformation) of gassy dense sand to deformation decreases under undrained condition. After the constant shear stress path reaches the point of instability, the transient liquefaction bulging failure occurs in gassy dense sand under drainage condition and gradual shear failure occurs under undrained condition.
作者
孔亮
刘文卓
袁庆盟
董彤
KONG Liang;LIU Wen-zhuo;YUAN Qing-meng;DONG Tong(School of Sciences,Qingdao University of Technology,Qingdao,Shandong 266033,China;Research Institute for National Defense Engineering of Academy of Military Sciences PLA China,Beijing 100850,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第9期3319-3326,共8页
Rock and Soil Mechanics
基金
国家自然科学基金项目（No.11572165,No.51778311）~~
关键词
天然气水合物
含气砂土
常剪应力路径
三轴试验
natural gas hydrate
gassy sandy soils
constant shear stress paths
triaxial tests
