A numerical model of water evaporation from cracked soil

Abstract

Cracking is a common phenomenon in clayey soils under soil-atmosphere interaction. It strongly promotes water evaporation and further affects thermo-hydro-mechanical behavior and engineering properties of soils. In this study, a new numerical approach is proposed to simulate water evaporation in cracked soils. The new approach divides the cracked soil into two domains: the soil domain follows a coupled hydro-thermal approach and the air domain follows Fick’s law. The boundary conditions of the two domains are identified by the vapor flux with a suction-related evaporation model. Two sets of numerical tests are performed to examine the effects of air humidity and segmentation method on soil evaporation rate and volumetric water content profile versus time. Results reveal that soil water content near soil surface and soil crack surface decreases more rapidly. The more segments of crack surface are conducted, the more realistically it can reflect the variation of crack surface evaporation in depth, but it will increase the computational burden. Air humidity does affect the rate of evaporation and the larger the relative humidity, the lower evaporation rate. Furthermore, the presented numerical approach provides a benchmark for a satisfactory description of water evaporation from a clayey soil with cracks.