Experimental analysis of infiltration process and hydraulic properties in soil and rock profile in the Taihang Mountains, North China

In this research, an experiment was conducted in the Taihang Mountains in China with a self-designed automatic soil and rock water infiltration monitoring system and a time domain reflectometry (TDR) device to analyze the infiltration process of disturbed soil and rock profile under constant head, unsaturated seepage properties and permeability coefficient of discontinuous rock masses. It was found that the infiltration process curve has an obvious fluctuation in the late stage of unsaturated seepage (after 18:00 p.m. on March 20th) which not only reflects the temporal variation of infiltration rate, but the spatial variation of rock structure. The lateral soil water of soil and rock dual-texture mainly flows in the interface of soil and rock. The infiltration rate of soil water can be as high as 2.42 × 10−4 cm/s, accounting for about 20% of the stable infiltration rate. After the water infiltrated in the lower rock layers, the water was mainly stored and flowed in the fissure network in the rocks, but did not completely fill the whole fissure network. Firstly, the local priority channel is adopted to infiltrate. With the increasing of rock saturation, the local priority channel will also expand and finally extend to the whole fissure network. The permeability coefficient of the soil and rock dual-texture in the study area is 1.26 × 10−3 cm/s.