大井法分段降水设计在南水北调中线工程中的应用

Application of Segmented Dewatering Design Based on Big-well Method to the Middle Route of South-to-North Water Transfer Project

现阶段工程降水设计以大井法为主,但对于长宽比差距悬殊的渠道,应用大井法时会出现较大误差.以南水北调中线温博Ⅱ标段渠道降水工程为例,提出将渠道分成若干段后采用大井法进行降水设计,并以不同长度(降水井影响半径2倍长度即150 m、将渠道分成3段即每段333 m和不分段即1 000 m)为分段依据,应用Visual Modflow软件进行降水数值模拟.结果表明:分段长度直接影响降水效果,随着分段长度的增加,降水效果会变差;采用降水井影响半径的2倍长度作为分段依据是可行的,符合降水设计要求.

The engineering dewatering design gives priority to the big-well method at present, but as to this kind of channel which the length-width ratio is large, the big-well method is inapplicable and a larger error will occur. In this paper, taking the channel dewatering project of Wenbo Ⅱ section in the middle route of South-to-North Water Transfer Project as an example, it was proposed that the whole channel was firstly devided into several segments, and then the big-well method was used to the dewatering design. Visual Motiflow software was applied to numerical simulation on dewatering with different lengths for segmented basis which adopted 150 m, namely 2 times of the radius of influence of dewatering well, 333 m, namely the channel being divided into 3 segments and 1 000 m, namely the whole channel length. The results show that the segmented length affects dewatering effect, as larger the segmented length is, the worse dewatering effect is. It is applicable that 2 times of the radius of influence of dewatering well is used as the segmented basis, which is in line with the requirement of dewatering design.