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设计了专门的毛细水输盐模拟试验装置,在精确控制温度、湿度和供水水头的情况下,监测不同孔隙溶液在含盐及脱盐澄板土地仗中的毛细迁移特征。水盐迁移前后,测定模拟地仗的导热系数、孔隙半径变化,从微观角度判断外来盐分及地仗内存在的盐分对地仗盐害的贡献。试验结果表明,溶液毛细迁移速率由大到小排列为KCl与Na_2SO_4混合溶液>KCl溶液>Na_2SO_4溶液>H_2O。毛细上升速度随着试样高度的增加逐渐减慢,而且脱盐澄板土中的毛细上升速率大于天然澄板土中的速率。孔隙溶液电导率随试样高度增加呈递增趋势,且天然澄板土试样的电导率普遍高于脱盐澄板土。试样的导热系数随高度的增加出现先减小后增加的总体趋势。脱盐澄板土与天然澄板土相比,孔径分布密度偏向小孔径方向;当迁移溶液为混合盐时,孔径分布较单一盐溶液时集中。模拟试验结果发现,毛细输送的外来盐分(特别是硫酸盐和氯化物复合盐)造成的土体盐胀破坏比土中既有盐分更加显著,说明控制降水入渗引起的化学淋滤作用对预防顶层洞窟壁画盐害具有重要意义。
A special capillary water and salt transport simulation test device was designed to monitor the capillary migration characteristics of different pore solutions in the land battle of salty and desalinated clay plates under the precise control of temperature, humidity and water supply head. Before and after the migration of water and salt, the thermal conductivity and pore radius of the simulated battles were measured, and the contribution of the salinity existing in the external salt and earth battles to salt damage was judged microscopically. The results showed that the capillary migration rate of the solution arranged in descending order KCl and Na_2SO_4 mixed solution> KCl solution> Na_2SO_4 solution> H_2O. The capillary ascending speed decreased gradually with the increase of sample height, and the rate of capillary rise in desalinated chert plate was higher than that in natural clays. The conductivity of porous solution increases with the increase of sample height, and the conductivity of natural Clayey soil samples is generally higher than that of demineralized clayey soil. The thermal conductivity of the sample with the increase of the height of the first decrease and then increase the overall trend. Compared with natural clayey soils, the density of pore size distribution of desalinated clayey soils tends to the direction of small pore diameter. When the migrating solution is mixed salt, the pore size distribution is more concentrated than that of single clayey soils. The results of the simulation experiment show that the capillary salt desalination caused by extraneous salt (especially the sulfate and chloride compound salts) is more significant than the existing salt in the soil, indicating that the chemical leaching action caused by the control of precipitation infiltration can prevent the salt Salt mural painting on the top floor is of great significance.