Exploitation of gas hydrate requires an improved understanding of the behavior of gassy soil. In this study, a numerical simulation technique is proposed that uses the discrete element method (DEM) to evaluate the undrained mechanical behavior of gassy sand, which consists of three phases—sand particles, water, and gas. The governing equation of gassy sand under undrained condition is derived and incorporated into the DEM simulation, in which gas solution and exsolution are considered. Undrained isotropic unloading and undrained triaxial compression tests on gassy sand samples with dissolved methane and carbon dioxide are simulated. Reasonable consistency is found when the simulation results are compared with experimental observation and theoretical calculation. The simulation highlights the significant influence of the gas solubility on the undrained behavior of gassy sand. The micro-responses of the observed phenomenon are also investigated.
探讨了太阳紫外辐射对两种 N 水平条件下羊栖菜藻体光化学特性的影响及其恢复.结果显示,在高的光辐射下羊栖菜藻体的有效光化学效率和相对电子传递速率急剧下降,两种 N 水平条件下藻体的光化学活性下降趋势一致;在全波长太阳辐射条件 ( 即高的光辐射和紫外辐射同时存在 ) 下它们的下降幅度更大,而 N 加富条件下羊栖菜藻体的相对电子传递速率要高于对照 N 水平下生长的藻体,表明 N 加富的生长条件使得藻体具有更高抵御紫外辐射的能力,这可能是与 N 加富生长条件下的藻体中含有较高含量的紫外吸收物质和类胡萝卜素有关.在低光恢复过程中,全波长辐射处理藻体的有效光化学效率比可见光辐射处理藻体的恢复要慢 ( 分别为 6 h 和 3 h 可恢复到起始水平 );而相对电子传递速率的恢复能力则比有效光化学效率的恢复能力更弱,需要 24 h 或者更长的时间. 相似文献
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