铁路跨河桥梁工程防洪评价常见问题探讨

Discussion on common problems of flood control evaluation for high-speed railways across rivers

针对连淮扬镇高速铁路约200座桥梁工程要考虑防洪评价共性问题,如大量桥墩布置在行洪或排引水渠道内、堤身设计断面布置桥墩、桥轴线法向与水流交角偏大等进行总结并探讨解决措施、提出建议。导致桥墩位置布置不合理的最根本原因是铁路线位的确定过程中水利部门参与不深入,防洪评价专题工作开展滞后,未能在设计时充分考虑堤防安全、河势稳定、行洪通畅等因素。另外,方案设计仅依据已颁布的水利相关规划,未参考正在编制或修编中的重大水利规划是引起防洪安全隐患的另一重要原因。高铁桥墩通常尺度较大,有明显水流控导作用,墩柱与水流交角较大时会引导水流冲刷堤岸,对堤防安全造成直接威胁。分析表明加大桥跨和偏转桥墩是两种潜在的解决方法,但前者增加投资成本,后者受限于当前桥梁设计理论,加大桥跨可能伴随施工困难显然不是最佳解决途径,桥梁设计的"斜桥斜做"理论亟待突破。

Railway bridge construation across the river is difficult to avoid. Bridges are the most common solutions which must be permitted by the river authority of local government according to the related flood control evaluation reports. This paper summarizes the experiences for related flood control problems and the solutions for about 200 river bridges encountered during the flood control evaluating of the sample high-speed railway by which four cities（ Lianyungang,Huaian,Yangzhou and Zhenjiang） will be connected. The most common problems are all connected to the piers located on the rivers and channels,even on the dike-sections,in an improper way or direction. The basic reasons of the unreasonable layout include the lagged appointment of the flood control evaluation. The water resources mangement departments have no chances to deeply participate in the designing process to make it possible that the solutions will be consulted comprehensively concerning dyke safety, river stability, flood discharge unobstructed,etc. On the other side,it is not enough for river bridges designing only according to the plans published years ago. The related plans,especially the one to replace the current one,should be included as an important law of design to fit the permanent railway project. The railway bridge piers usually have a large size,which will guide the flow toward the bank of the river when they cross with the direction of runoff. This water erosion is a direct threat to the natural earth banks which can not keep stable in the flood. Increasings of bridge spans and bridge piers are two potential solutions. But the former will increase investment costs,while the latter is limited to the current bridge design theory. It is obviously not the best way to solve the problem. The increasing of the bridge span may be accompanied by construction difficulties. Therefore,the bridge design theory of ＂make the bridge pier axis cross the railway and follow the flow＂needs further development.