RESUMEN
With the development of desertification in the Qinghai-Tibet Plateau (QTP), aeolian sand becomes the remarkable local factor affecting the thermal state of permafrost along the Qinghai-Tibet Engineering Corridor (QTEC). In this study, a model experiment was conducted to analyze the impact of thickness and water content of aeolian sand on its thermal effect, and a hydro-thermo-vapor coupling model of frozen soil was carried out to reveal the heat transfer mechanism of the aeolian sand layer (ASL) with different thicknesses and its hydrothermal effect on permafrost. The results indicate that: (1) ASL with the thickness larger than 80 cm has the property of converting precipitation into soil water. The thicker the ASL, the more precipitation infiltrates and accumulates in the soil layer. (2) The cooling effect of ASL on permafrost results from the lower net surface radiation, causing the annual average surface heat flux shifting from heat inflow to heat outflow. The warming effect of ASL on permafrost results from the increasing convective heat accompanying the infiltrated precipitation. (3) As the ASL thickens, the thermal effect of ASL on permafrost gradually shifts from the cooling effect dominated by heat radiation and heat conduction to the warming effect dominated by precipitation infiltration and heat convection. The warming effect of thick ASL on permafrost requires a certain amount of years to manifest, and the critical thickness is suggested to be larger than 120 cm.
Asunto(s)
Hielos Perennes , Tibet , Suelo/química , CalorRESUMEN
Although electroosmosis has been confirmed to be a promising technique for stabilizing soil with low permeability and high water content, several issues remain with this innovative method, including high power consumption, nonuniform strengthening effect, and electrode corrosion. In this context, for improving the feasibility of electroosmosis, a set of comparison laboratory tests were performed in customized apparatus to investigate the efficiency of intermittent current for the dewatering and consolidation of silty clay in the presence of calcium chloride. In this study, the time intervals of 0, 1, 2, 4, 8â h were, respectively, combined with 15% calcium chloride solution during the process of electric treatment. By comparison with conventional electroosmosis, the test results apparently indicated that intermittent current incorporated with calcium chloride not only increased the undrained shear strength of soil matrix, but also reduced the anode corrosion and power consumption induced by the injection of CaCl2 solution, which made the process economically feasible in practical projects.