68 / 2019-07-27 18:45:03

Effects of drying-wetting cycles on hydraulic properties of a cracked soil

drying-wetting cycle,desiccation cracking,infiltration,permeability

水库地质灾害防治与生态环境保护 > 表生地质作用与地质灾害演化过程

Natural and engineered soils are always subjected to diurnal and seasonal weather changes and undergo periodical drying-wetting cycles. During the drying process, desiccation cracking is one of the typical engineering geological characteristics of soils. Cracks may provide preferential pathways for water flow, which significantly increases the permeability of the soil mass and further induce many problems in geological and geotechnical projects, such as slope instability and dam failure. In this study, three drying-wetting cycles are applied on a compacted expansive soil. During the drying process of each drying-wetting cycle, seven specimens with various water contents (25%, 23%, 21%, 19%, 17%, 15% and 13%) are subjected to the infiltration test. Geometric characteristics evolution of surface crack patterns during the drying-wetting cycles are monitored. Effects of drying-wetting cycles on the infiltration rate and saturated permeability of soil specimens at different water contents are also analyzed. Experimental results show that with decreasing water content, crack initiates and propagates gradually and further develops with increasing drying-wetting cycles. With decreasing water content, the initial infiltration rate increases. For the soil specimen without cracks, the infiltration rate decreases with elapsed time dramatically before saturation. However, for a cracked soil, the infiltration rate keeps constant at the early stage, followed by reduction and stabilization. Desiccation cracking results in an increasing in saturated permeability, up to two orders of magnitude.