Water Movement In Bio-Slope-Engineering And Stability Analysis Of The Shallow Slope

Landslide is closely related to rainfall, and for unsaturated soil slope the rain infiltration is one of the most important factors that results in landslide. The stability of loess slope has aroused more and more attetion with the development of the loess plateau area. But the study on effect of bio-slope-engineering loess shallow slope stability under rainfall is not so perfect. The variation of water distribution in unsaturated slope and the bio-slope-engineering shallow slope stability due to rain infiltration is studied in this paper. And the law of water-field distribution is analyzed theoretically under the influence of different factors such as rainfall intensity, rainfall duration, the style and gradient of the slope, the proportion of the carrying soil. And then the limit equilibrium method is used to calculate the shallow slope stability of loess slope influenced by different factors.Firstly, the character of loess in Sanmenxia area and the usual method of treat with loess slope are summarized. Also, Rainfall infiltration process and the factors affecting on rainfall infiltration are analyzed. The ameliorated Green-Ampt infiltration model which takes into account carrying soil based on Green-Ampt infiltration model of being applicable to loess area is proposed. Meanwhile some factors affecting on rainfall infiltration are analyzed. The result shows that the wetting front depth increase with the initial water content increase and soil water suction increase. The wetting front is affected by carrying soils level, which mainly depend on the penetration coefficient relationship bwteen the carrying soils and the subsoil. The impact of carrying soils level thickness on wetting front is smaller.Secondly, the limit equilibrium method is used to simulate loess slope transient seepage field under the rainfall infiltration. And the factors which influence on rainfall infiltration depth are analyzed. The result shows that the rainfall infiltration depth increase with rainfall intensity or rainfall duration increase and slope ratio decrease. The carrying soils level existence minish the rainfall infiltration depth. However, the impact of carrying soils level thickness on rainfall infiltration depth is very small.The bio-slope-engineering loess shallow slope stability analyses method based on analyse of rainfall infiltration is proposed. The result shows that the position of the most dangerous slip plane in slope shallow layer under rainfall is the depth of wetting front arrives. The smaller the length to width ratio of slip body is, and the bigger the slope ratio, rainfall intensity and rainfall duration are, the poorer the slope stability is. Meanwhile the lower initial water content is, and the bigger the root area to soil area ratio is, the better the slope stability is.