| China is a geological disaster-prone country, especially landslides. Intense rainfall is a critical factor for shallow landslide. Study on slope failure by rainfall is mainly based on reduced matric suction and increased weight. The effects of slope surface structure and the underlying bedrock layer on slope failure are researched rarely. Based on the infinite shallow slope, considering the effects of the underlying bedrock layer and surface treatment of terraced slope, this paper studied the intense rainfall infiltration process and slope stability of infinite shallow slope by using the Green-Ampt infiltration model. The main work and results are as follows:(1) The traditional Green-Ampt infiltration model was extended; Combining the stability analysis of the wetting front and the bedrock surface, a calculation model of safety factor for shallow residual soil slope was established during the entire rainfall infiltration; A discussion was conducted on varying cohesion, groundwater table and initial soil weight.(2) In view of the gas-water interface at the wetting front, the formation of closed air pressure at the wetting front was studied under conditions of intense rainfall, the results indicate that the closed air pressure is closely with the depth of ponded water, the depth of wetting front, pore size distribution and so on.(3) By amending the classic Green-Ampt infiltration model, the closed air pressure was introduced to slope stability analysis, the delay effect model and stability analysis model with closed air pressure were established.(4) Based on Green-Ampt infiltration model and Geo-studio analysis software, the infiltration process of infinite terraced slope and the potential slip surface properties were studied. Considering the horizontal surface and inclined surface of terrace units, the rainfall infiltration process of infinite terraced slope was simulated, and a stepped wetting front was founded.(5) Based on the limit equilibrium method the infinite terraced slope stability analysis models were established considering the horizontal surface and inclined surface of terrace units respectively. Combining the flow diagram, the slip surface depth of terraced slope can be calculated, the numerical results indicate that the models are applicable.(6) Based on the limit equilibrium method, an infinite terraced slope stability analysis model at the bedrock was established considering the groundwater and intense rainfall; For different weak rainfall intensity, a terraced slope stability analysis model at the bedrock was established for landslide induced by the rising groundwater, and the critical depth of groundwater induced by rainfall can be established.(7) Through the analysis of terraced slope slip surface depth, the cohesive strength and initial matric suction have great effects on the depth of the sliding surface. The sliding surfaces of many terraced slopes may be the fully wetted surface.(8) Since the inclined bedrock layers changes the rainwater infiltration process, based on the hypothetical sliding surface of two-folded line and the imbalance thrust force method, a stability model of slope with different bedrock slope angles was developed. By using Geo-studio analysis software the infiltration process of slope and the potential slip surface properties were simulated. |
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