长江流域中下游沿江平原地区,建筑了很多各种类型的大小排水涵闸。为了满足排水灌溉的需要主要型式分通天闸与涵洞两种,排水任务大的建闸,小的建涵洞。由于沿江多属冲积土层,承载力低,堤身又高,不论建闸或建涵,在技术上都有一定困难。建闸则闸身与土堤接合处,因荷重悬殊,再加以侧向防渗问题 The middle and lower reaches of the Yangtze River Basin along the plains, the construction of many different sizes of drainage culvert. In order to meet the needs of drainage and irrigation, the main types of sub-gates and culverts are divided into two types, large drainage gates, and small culverts. Since many alluvial soil layers along the river have low bearing capacity and high embankments, it is technically difficult to build sluices or construct culverts. Gate construction is then gate and embankment junction, due to load disparity, coupled with the lateral seepage problems