回溯五十年代修建宝成铁路时,成都到绵阳段大中桥梁很多。其特点是桥长、跨短、墩低、水浅,河床地质大部分为砂卵石。有一座大桥21孔跨径均为15.8米的钢筋混凝土简支梁,墩台最高10米,最大洪水深4.6米。据此,该桥原设计一律采用木桩基础。由于木桩打不下去,经过反复研究,改用扩大基础,将墩台直接建在砂卵石地层上。据不完全统计,这种 When going back to the 1950s when Baocheng Railway was built, there are many bridges between Chengdu and Mianyang. Its characteristics are long bridge, short span, pier low, shallow water, most of the river bed for the sand and gravel. There is a bridge 21 holes span are 15.8 meters of reinforced concrete simply supported beams, piers up to 10 meters, the maximum depth of 4.6 meters deep. Accordingly, the original design of the bridge should be based on stakes. As the stakes can not afford to go through repeated studies, use to expand the foundation, the pier will be built directly on the sand and gravel stratum. According to incomplete statistics, this