Unsaturated seepage characteristics in the slope characterized by a weathered rock-soil dual entity

To study the effect of soil-rock's characteristics on the transformation and redistribution of precipitation, the characteristics of unsaturated seepage in disturbed rock-soil entity were measured using a large man-made lysimeter during a rainfall event. Results indicate that the dual-media model should be adopted to calculate the amount of unsaturated seepage in rock layer, considering the difference of rock and fissure filler, and the rock and filler are the two medias. Water amount is calculated separately according to the volumetric content of water in various media and the volume of corresponding media, and the sum is the total water amount in lower rock layer. Subsurface flow only occurs as there is aquitard and a relative high aquifer at the lower part. Lateral preferential flow emergences as rainfall in the high aquifer infiltrates into the boundary of soil and rock, and then water moves quickly along the fissures of rocks in vertical and horizontal dimensions. Unsaturated seepage in rock layer is strongly affected by the weathering intensity of the fissured rock. If rock is highly weathered, a certain amount of water also moves in the surface layer of the rock except for in the fissures.