大沽河野外垂向入渗试验研究

Study on the Field Vertical Infiltration Test of Dagu River

选取季节性河流大沽河上、中、下游3处代表性河床作为野外垂向入渗试验场地,每处分别做2组试验,研究不同包气带水理及理化性质下河道入渗能力。结果表明:河道入渗过程可分为快速入渗、缓速入渗与稳定入渗阶段,总历时为1.3~2.0 h;不同河道包气带水理及理化性质影响着河道入渗过程,同一试验场地各组试验相同深度沙层初始含水率越小则入渗速率越快,相同深度沙层初始含水率相近时,上、中、下游沙层水分入渗速率依次减小;当同一试验场地各组试验沙样每层初始含水率之和相近时,各层之间初始含水率差距越小,则达到稳定入渗的时间越短;随上、中、下游沙样粒径依次减小,其稳定入渗率依次减小,约为0.006 5、0.004 1、0.002 3 cm/s。

The 3 places of typical riverbed were selected from the upstream,midstream and downstream of the seasonal river of the Dagu River,and the field vertical infiltration experiments conducted based on the theory of streambed aeration zones water-bearing medium infiltration,each site of 2 tests respectively.Capacities of infiltration under water-physical and physicochemical properties in riverbed in different aeration zones were studied.The results show that the infiltration process in the riverbed can be divided into three stages:the rapid infiltration,the slow infiltration and the stable infiltration and it lasts about 1.3-2.0 hours;the infiltration in the riverbed is affected by the water-physical and physicochemical properties of aeration zone;The smaller initial water content of the same depth sand layer in the same test site,the faster the infiltration rate,when the initial water content of the same depth is similar,the infiltration rate of the upstream,midstream and downstream sand layers decreases in turn;when the sum of the initial moisture content of each group of sand samples in the same test site is similar,the smaller initial water content gap between the layers and the shorter the time to achieve stable infiltration;with the decrease of the size of the sand sample in the upper,middle and lower reaches,the steady infiltration rate decreased successively,about 0.006 5,0.004 1 and 0.002 3 cm/s.