In-situ observation research on the regularities of water migration in loess

摘要

A 10 meter depth exploration shaft was dug in Zhengning County, Gansu Province, where is located in the south of the loess plateau. The water content probes were installed on the wall of the shaft to monitor water migration process in the loess as the precipitation infiltrating in it. Since Oct. 16th 2010 to recent, 145 days of the water content data in different depths have been obtained. It is shown that as rainfall intensity is about 10mm/d, depth influenced by water infiltration is less than 0.3m. However, after rainy season of concentrated precipitation, part of the precipitation infiltrates into the loess and migrates further to a deep position. The water migration in the soil above 3m is swift, but slows down with the depth increasing. As encountering a relative poor permeability bed, the water would gather on the bed to increase water content in the loess. For impervious bed, water content increases accumulatively with infiltration supplies of the intermittent precipitation. This phenomenon may reveal the mechanism of the loess landslides induced by rainfall or irrigation.