FIELD TESTS ON SEEPAGE REGULATION OF AGGREGATE GRAVEL SOIL UNDER ARTIFICIAL HEAVY RAINFALL

Heavy rainfall can change the permeability characteristics of aggregate gravel soil, which is the key factor triggering landslides, mudslides and other type of rainfall-induced disasters. This paper explores the dynamic mechanism of landslide induced by rainfall infiltration. Self-made one-dimensional permeameter and two-dimensional slope model are used for the representative gradation gravel soil test close to Shuizuwan Tunnel. Then, further research focuses on the seepage regulation of aggregate through Seep/w software. The results show that: there is a step-ladder trend between wetting front and time curve. More specifically, wetting front migration rate can rapidly increase with the sudden increase of the topsoil moisture to a maximum. It can slowly decrease with increased pressure. Finally the wetting front migration rate can slightly increase with the decreased pressure. The average rate of wetting front migration approaches a linear growth with the increased rainfall intensity. Development of soil settlement deformation passes through three stages. They are slow growth, sharply rises and gradually stagnation. The one-dimensional infiltration rate has a power, logarithmic and linear relations with the slope infiltration rates at top, middle and toe of the slope, respectively. The final depth of rainwater infiltration is the toe of slope, the top of slope and mid-slop in order descending.