Effect Of Rainfall Infiltration On Stability Of Loess Slope

Loess is a common wind deposit in mid-latitude semiarid region, widely distributed in the loess plateau. Due to the wind, gravity, especially the effect of hydraulic, loess plateau presents the characteristics of fragmented, ditches and high slope of development. And loess itself has evident characteristics of wet soft, unsaturated, vertical joints growth, that lead to the area of landslides occur frequently, and rainfall is push power, So the research of effect of rainfall infiltration on loess slope stability has high practical and scientific significance.Based on the theory of saturated-unsaturated seepage and unsaturated soil mechanics, and used large geotechnical analysis software FLAC-3D as research platform, detailed analysis and research the loess slope of vertical joints growth with the rain infiltration process, and the process of water sink along large cracks and soil porosity sink respectively. On this basis, this paper discusses the rainfall condition prolapse draw crack depth impact on slope stability, and contrast the prevention measures and non-prevention measures for safety and stability of loess caves in the rain infiltration process. The obtained conclusions are as follows:(1) In the process of rain infiltration along homogeneous loess, moist peak maintained horizontal and constantly gone downward. In different rainfall intensity circumstances, water infiltration depth increased with the time, and infiltration rate increased with infiltration depth decreases. In the process of rainwater along the fissures infiltration, the function of the loess vertical joints to moisture infitration promote firstly, further reduction, and suppression last.(2) For the loess slope of no crack, in the continuous rainfall different permeability coefficient ratio and slope safety coefficient decreased with rainfall duration. And the larger the permeability coefficient ratio, the earlier time the slope safety coefficient show apparent drop. Under the condition of the same rainfall intensity and rainfall duration, the displacement of keypoint increased with the permeability coefficient ratio increases, In a fixed permeability coefficient ratio, the displacement of keypoint increased with rainfall duration increased.(3)In the condition of no rain, safety coefficient decreased with cracks depth increased, and there is a critical value; The rain infiltration make safety coefficient decreased obviously with the increase of depth of fractures, criticality fracture depth value of the fracture slope was not obvious, Whether there is a fracture, safety coefficients decreased with rainfall duration, and the decreased amplitude accrescent.(4) It existed dangerous area of solp safty coefficient lowest in the top of slop, Researching department to meet the minimum safety factor of slope dangerous area, the farther cracks away from the area, the higher slope stability; when the distance is far enough, its impact on slope stability can completely ignored.(5) The safety of the same caves decreased with precipitation intensity and precipitation increases, it was significant effect that the roof of the waterproof prevention measures for caves safety. Combined with examples, as long as the width of the impervious layer more than twice hole width, it can achieve purposes of safety, reasonable and economic.