由于梁内污水和大气污染物的腐蚀，圬工梁泄水孔，特别是水平放置的铸铁管外露部分极易锈蚀腐烂，导致梁上污水淋挂造成梁体污染，影响梁体质量。我段宁芜线30k＋988处4号桥1979年投入运营后，由于周围工矿区矿6运输等污染严重，铸铁泄水管锈蚀腐烂，虽多次采用3－5毫米钢板做 Due to the corrosiveness of the sewage and air pollutants in the beam, the leakage holes of the girder, especially the exposed parts of the horizontally cast iron pipe, are extremely prone to rust and rot. As a result, the water leaking on the girder causes the beam body to be polluted and the beam body quality is affected. I paragraph Ningwu line 30k + 988 at No. 4 Bridge put into operation in 1979, due to surrounding mining area mine 6 transport and other serious pollution, corrosion and decay of cast iron drain pipe, although the use of 3-5 mm steel plate