Moisture Diffusion of Soils with Gravel in the Karst Region
Karst topography is primarily developed in southwestern China,heavily featured by shallow soil layers and exposed bedrock.Gravel(particle size＞2 mm)are the regular components of the soil in karst areas,leading to complex soil moisture migration in the soil.Most previous studies focused efforts on vertical infiltration analysis of karst soils under hydrodynamic conditions,and little addressed to their horizontal water diffusion capacities.In this study,it experimentally investigated the soil moisture diffusion capacity of karst soils.Horizontal soil column diffusion experiments were designed to examine the progressive phases of soil wetting front and soil moisture diffusion rate for five sets of remolded karst soils with gravel contents of 0,10％,20％,30％,40％.(1)With the same gravel content of all soil samples,the advancement distance and speed of soil wetting front both had a power function relationship with time.As horizontal diffusion of moisture progressed,the volumetric moisture content of the soil column gradually decreased,accompanied by Boltzmann transformation parameter λincreasing exponentially,suggesting soil moisture diffusion rate decreasing simultaneously.(2)With the gravel content of soil samples increasing,the advancement distance and speed of soil wetting front generally show an increasing trend with the increase of gravel content,but both the advancing distance and average speed of the wetting front decrease when the gravel content is 10％.At the same location,volumetric water content increased with a higher gravel content,accompanied by soil moisture diffusion rate in descending trend of 40％＞30％＞20％＞0＞10％of gravel contents.The study would provide a experimental basis for understanding of soil hydrological cycles and processes in karst region of China.
gravel contentmoisture diffusionwetting frontkarst region
NETL
NSTL
万方数据
