Experimental Study On Hydraulic Response Of Red Clay Slope Under Rainfall Infiltration

In order to investigate the influence of slope gradient and rainfall patterns on the characteristics of infiltration response of red clay slope under rainfall condition,indoor experiments with simulated rainfall on red clay slope under 30 ° and 45 ° slope and one dimensional soil column tests with 3 different simulated rainfall patterns named advanced pattern,uniform pattern and delayed pattern are carried out respectively.During the experiments,the volumetric water content and matric suction inside the soil are monitored,and the influence of different slope gradients and rainfall patterns on the varying characteristics of soil moisture,vertical water transfer rate,distribution of maximum water content and response of matric suction of red clay slope are analyzed.The results show that the gradient of slope is an important factor affecting the infiltration response of red clay slope.In the process of rainfall,in the shallow layer of slope,compared with other positions,the top platform of gentle slope has the maximum vertical average water transfer rate,while in the steep slope,the vertical water transfer rate under the top platform is relatively low,and the former is about 6.2 times of the latter.At the same time,in this depth range,the average vertical water transfer rate in the toe,middle and the top of the gentle slope is 0.8 times,0.7 times and 0.5 times higher than that in the steep slope.In addition,the change range of the maximum volumetric water content at the middle and top of slope increases with the increase of the gradient of slope.The matric suction at the toe of slope is not the first to lose,but with the increase of slope,although the loss range at the toe of slope changes little,the loss rate will increase,while the loss rate at the middle and the top of slope will decrease.The results also show that the water content of the soil profile has different varying characteristics under different rainfall patterns.Under single peak rainfall patterns,the volumetric content of the near-surface soil will fall back when it reaches its peak value,and the maximum amplitude of the fall back can reach 5.3%.In addition,the influence depth of single peak rainfall patterns is deeper than that of the uniform rainfall pattern,and its maximum water transfer rate is about 77% higher than the uniform rainfall pattern.The average rainfall intensity during and ahead of the water migration are the main factors affecting the vertical average water transfer rate.At the same time,the effect of rainfall pattern on water transfer rate will decrease with the increase of depth.At the end of the rainfall,rainfall events with single peak patterns may cause larger loss of matric suction than the uniform pattern near the the wetting front.