| Rainfall infiltration is an important factor inducing loess slope instability.The law of soil water infiltration has always been a hot spot in this field.Aiming at the instability disaster of loess excavation exposed slope caused by rainfall infiltration,based on the indoor soil column infiltration test of accumulated rain and no accumulated rain,this paper simulates the water infiltration law of slope soil under different rainfall conditions based on the HYDRUS-1D software model,analyzes and verifies the simulation results,and explores the water infiltration law of different types of slope soil in combination with field tests,Finally,based on FLAC3D software,the influence of soil moisture infiltration on slope stability under the conditions of accumulated rain and no accumulated rain is simulated and analyzed,which provides a theoretical and scientific basis for the numerical simulation and stability analysis of loess slope moisture infiltration under the conditions of rainfall.The main research results obtained are as follows:（1）A one-dimensional unsaturated infiltration model is established based on HYDRUS-1D software to simulate the water infiltration law of accumulated rain and non accumulated rain loess under the condition of rainfall infiltration.The variation trend of the simulated value is consistent with the measured value.Under the condition of accumulated rain,the RMSE range is 0.011～0.017,and the NSE is more than 0.9except 20cm;The RMSE range is between 0.023～0.039,the NSE is above 0.7,and the evaluation indexes are within a reasonable range under the condition of no accumulated rain.The simulation accuracy is high.HYDRUS-1D software can better simulate the infiltration law of soil water under different rainfall infiltration conditions.（2）The order of sensitivity of soil moisture characteristic parameters under accumulated rain and no accumulated rain is>6)>n>α>.anddisturbances are negatively correlated with the simulation results,6)、n、disturbance is positively correlated with simulation results,and the accuracy of high sensitivity parameters should be ensured during simulation.（3）The effect of rainfall infiltration on soil moisture in different profiles is that it has a greater impact on the soil moisture content in the 0-40cm profile in the shallow layer,and a smaller impact on the deep layer in the lower layer.The existence of vegetation can make the water more fully infiltrated in the shallow layer,which leads to the shallow infiltration depth.The water storage and water retention capacity of grassland is better than that of farmland,bare slope and forest land.The response of different types to rainfall has hysteresis.（4）With the increase of rainfall infiltration depth,the strain zone of slope soil gradually develops from the toe to the top of the slope,and the stability of the slope gradually becomes worse.The safety factor of the slope decreases with the increase of infiltration depth.The safety factor of the slope under accumulated rainfall infiltration decreases from 2.46 in natural state to 0.76 when the infiltration depth is 200cm,The safety factor of the slope without rain accumulation infiltration decreases from 2.46 in the natural state to 0.72 when the infiltration depth is 200cm.With the same rainfall infiltration duration,the safety factor of the slope is smaller under the condition of accumulated rain,and the time of landslide caused by slope instability and failure is earlier.Under the same infiltration depth,the safety factor of the accumulated rain and the non accumulated rain slope is slightly different,which may be mainly due to the different depth of the transition zone. |
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