【作者】 赵世平；

【导师】 刘建生； 钱天伟；

【作者基本信息】 太原科技大学 ， 材料加工工程， 2008， 硕士

【摘要】 当今世界,原煤、石油、天然气等能源日益紧缺,世界各国都面临着能源危机,核能越来越得到世界各国的重视,核能必定会有一个更大规模的发展。但随着核能的广泛利用,必将产生越来越多的核废物,核废物的如何安全处置成为人们日益关注的焦点。目前核废物处置多采用地质处理方法。核废物经过加工处理后,再放入处置库与外部环境隔离,尽量避免水分进入处置库。顶盖是放射性废物近地表处置库的重要工程屏障。毛细屏障是顶盖中一个非常重要的部分,一般由细颗粒介质的下面铺设粗颗粒介质而成的。当水分入渗到粗-细颗粒介质交界面上方时,由于毛细作用使得水分不能从细颗粒介质层进入粗颗粒介质层,从而在界面上方积累,如果界面有一定坡度,水分会沿着界面横向传导。本文以喷淋强度、界面坡度和粗砂层厚度为影响因素,系统地展开了其对毛细屏障的效应研究。通过设计箱体实验,研究在非饱和状态下,以不同的喷淋强度表征不同的降雨情况,分析了其对毛细屏障的影响作用。设定5、15、20和25 mm/d的喷淋强度,测量水分经过粗-细砂介质交界面的相对绕流量。结果表明,在粗砂的厚度不变的前提下,喷淋强度越大,相对绕流量越少,毛细屏障的作用越弱。研究了粗石英砂的厚度对毛细屏障的影响情况。设定1mm,3mm,5mm,7mm,15mm和30mm等粗石英砂层厚度,在给定喷淋强度下,结果表明绕流量随着粗砂层的厚度增加而增加,证实了粗颗粒介质层的厚度越大,越有利于水分绕流现象的发生。同样,增加毛细屏障的倾斜度,可以增强毛细屏障的阻水能力。在对相对绕流量的定量观测的同时,也测定了箱体中粗细石英砂层各个位置的基质势,从能量角度对毛细屏障的水流规律作了解释,为更进一步探索复合效应对毛细屏障的影响奠定了基础,为核废物处置库的顶盖设计提供参考。更多还原

【Abstract】 In the modern world, the lack of energy sources such as coal, petroleum, natural gas becomes serious gradually, all the country in the world have to confront the energy crisis, so nuclear energy will get more and more attention from them. Nuclear energy will get sweeping development as a well developing Energy Substitute. But as the widely use of nuclear energy, there will be more and more nuclear waste. So how to dispose nuclear waste safely will be the focus of the people.Nuclear waste is often disposed by the method of geological disposal at the present time. First, Processing,then put it in waste repository isolating from external environment, avoiding the water infiltration into the nuclear waste repository to the best of its ability. Cover of low-andintermediate level radioactive waste disposal in near-surface facilities is a useful barrier. One important section, consisting of a coarser soil layer usnderlying a finer soil layer, called capillary barrier. Such a configuration is, in reference to the mechanism of capillary tension that limits water’s downward movement from a finer soil into a coarser soil, causing temporary water storage in the upper soil layer, if the fine-coarse interface is sloped, water in the fine layer can also drain laterally. This paper presents the systemic research of capillary barrier effect, taking infiltration rate、inclination of slope and thickness of coarser soil into account.To study its performance of the capillary barrier consisting of fine-over-coarse quartz sand layers, it is subjected to different infiltration rates simulating different rainfall in an infiltration box apparatus under unsaturated condition. The barrier was subjected to several infiltration rate of 5,10,15,20 mm/day, successively .Through quantificationally measurement of the diversion water, we can conclude that the bigger the infiltration rate is, the more the penetration water is ,the less diversion water is, the weaker the capillary barrier is, under certain condition of invariable thickness.The impact of coarse layer thickness on the capillary barrier is investigated .The tests are carried on different thickness of coarse quartz sand ,ranging from 1mm to 30mm in a given infiltration rate. The results indicate that the diversion water becomes larger with the increasing of thickness of coarse layer, confirming the positive effect of bigger thickness of coarse layer on reducing penetration water. The increasing the angle of slope also helps to strengthen the capillary barrier effect.While quantificationally measureing the diversion water, the matric suction of different locations in and around the capillary barrier are also measured, which has layed the foundation for the exploring the multiplex effect on the capillary barrier, provided the reference for the design of cover in nuclear waste disposal.更多还原