大口井滤水孔的预留施工时,习惯采用两种方法:一是预埋木棒或木模,二是利用废旧钢管或塑料管。施工实践证明,这两种方法都不理想。采用第一种方法,模板加工制作、凿除均较麻烦。采用第二种方法,造价高,同时混凝土浇筑和沉井过程中管口均需封堵。 When preparatory construction of large-bore wells is adopted, it is customary to adopt two methods: one is to embed wood sticks or wood molds, and the other is to use old steel tubes or plastic tubes. Construction practice proves that neither of these methods is ideal. With the first method, it is more troublesome to make and remove the template. With the second method, the cost is high, and at the same time, the nozzles need to be plugged during the pouring of concrete and caisson.