不同雨强和坡比条件下黄土边坡降雨入渗研究

Study on Rainfall Infiltration of Loess Slopes Based on Different Rainfall Intensities and Slope Ratios

降雨诱发滑坡是我国黄土地区的主要地质灾害之一,为了给黄土边坡防护设计提供参考,采用室内边坡降雨模型箱,开展了2种降雨强度(中雨7.00 mm/d、大雨10.75 mm/d)和2种坡比(1∶0.5、1∶1)条件下的模型边坡降雨试验,实测边坡土体含水率、基质吸力及边坡形态变化情况,比较了不同降雨强度和坡比条件下降雨入渗的差异。结果表明:黄土边坡降雨入渗深度坡脚最大、坡顶次之、坡中最小,降雨入渗速率坡顶最高、坡脚次之、坡中最低,雨水的入渗能力随着入渗深度增加而减弱;降雨结束后边坡湿润锋深度坡脚最大、坡顶次之、坡中最小,即降雨入渗深度坡脚最大、坡顶次之、坡中最小,降雨强度越大边坡湿润锋深度越大,坡比越大边坡坡中降雨入渗深度越小;不同降雨强度和坡比条件下,边坡不同位置处基质吸力稳定值坡中最大、坡顶次之、坡脚最小,降雨强度越大基质吸力稳定值越小、相应的含水率越低、降雨入渗速率越高,坡比越小边坡坡中降雨入渗速率越高、入渗深度越大;降雨初期坡面未产生径流,随着降雨历时的延长,表土逐渐饱和、坡面产生径流现象,降雨强度和坡比越大边坡表层土体剥落越严重、坡面径流深越大。

Rainfall⁃induced landslide is one of the main geological disasters in loess area of China.In order to provide reference for the pro⁃tection design of loess slope,indoor slope rainfall tests were carried out under the two kinds of rainfall intensities(moderate rain at 7.00 mm/d and heavy rain at 10.75 mm/d)and the two kinds of slope ratios(1∶0.5 and 1∶1)by using an indoor slope rainfall model box.The moisture content of slope soil,matric suction and slope morphology were measured.The changes of soil moisture content,matrix suction and slope morphology were monitored,and the differences of rainfall infiltration laws were compared under different rain intensities and slope rati⁃os.The results show that the rainfall infiltration depth of loess slope is the largest at the foot of slope,the second at the top of slope and the smallest in slope,and the rainfall infiltration rate is the fastest at the top of slope,the second at the foot of slope and the slowest in slope,and the rainwater infiltration capacity decreases with the increase of the infiltration depth.After the end of rainfall,the slope with the maxi⁃mum wet front depth is at the foot of the slope,followed by the top of the slope and the smallest in the slope.Namely,the depth of rainfall in⁃filtration is the largest at the foot of the slope,followed by the top of the slope,and the smallest in the slope.The greater the rainfall intensity is,the greater the slope wetting front depth is.And the greater the slope ratio is,the lower the rainfall infiltration depth is.Under the differ⁃ent rainfall intensities and slope ratios,the matrix suction stability value of slope at different positions is the largest,followed by the top of slope and the foot of slope.The larger the rainfall intensity is,the smaller the matrix suction stability value is,the lower the corresponding water content is,and the faster the rainfall infiltration rate is.The smaller the slope ratio is,the faster the rainfall infiltration rate is and the greater the infiltration depth is.In the initial stage of rainfall,there is no runoff on the slope.With the extension of rainfall duration,the top⁃soil gradually is saturated and the slope surface produces runoff.The greater the rainfall intensity and slope ratio is,the more serious the slope surface soil exfoliation is,and the more significant the slope runoff is.