兰新铁路河西走廊漫流区桥涵水文沿线分布研究

Study on Hydrological Distribution along Bridges and Culverts in Overflow Area of Hexi Corridor of Lanzhou-Xinjiang Railway

为降低河西走廊漫流水害对兰新铁路的危害,通过山洪灾害分析方法,对河西地区缺少水文资料的漫流区流域桥涵水文沿线分布情况进行研究。结果表明:相比单位线法,数值模拟法可提高设计洪水的计算效率,且两者相对误差为4.6%,结果较准确;临界重现期越大,桥涵发生漫流水害可能性越大;当桥涵发生满孔水害时,降雨重现期越大,成灾持时越久;预警雨量与预警时长呈正相关性,与土壤含水量呈负相关性;兰新铁路沿线预警雨量自东往西存在增大的趋势,预警雨量相对较小的桥涵主要分布于包含山丹县的武威至高台段内;山丹县境内的桥涵设计水位最接近成灾水位;在选取的兰新线23座桥涵中,设计水位不满足百年一遇的有15座桥涵,包括中风险9座,高风险5座,极高风险1座,山丹县境内5座均为中高风险,应将兰新线漫流区内位于河西地区武威至高台段内的桥涵作为山洪防范的重点区域。

In order to reduce the hazard of diffuse flow water damage in Hexi Corridor to Lanzhou-Xinjiang Railway, a study on the hydrological distribution along the bridges and culverts in the overflow area watershed in the Hexi region with a lack of hydrological information was conducted by means of flash flood disaster analysis. The results show that compared with the unit line method, the numerical simulation method can improve the calculation efficiency of the design flood, the relative error is 4. 6%, and the results are more accurate. The greater the critical recurrence period, the greater the possibility of diffuse flow water damage in the bridge and culvert, and when the bridge and culvert are flooded with full holes, the greater the rainfall recurrence period, the longer the disaster duration. The early warning rainfall is positively correlated with the early warning duration, and negatively correlated with the water content of soil. The early warning rainfall along the Lanzhou-Xinjiang Railway has an increasing trend from east to west, and the bridge and culvert with relatively small early warning rainfall is mainly distributed in the section from Wuwei to Gaotai, including Shandan County. The design water level of bridges and culverts in Shandan County is closest to the disaster flood stage. Among the selected 23 bridges and culverts of Lanzhou-Xinjiang Railway, there are 15 bridges and culverts whose design water levels do not meet the once-in-100-year event, including 9 medium risk, 5 high risk, and 1 extremely high risk, and all the 5 bridges and culverts in Shandan County are medium and high risk.The bridges and culverts in the overflow area of Lanzhou-Xinjiang Railway located in the Hexi region from Wuwei to Gaotai section should be taken as the key areas for flash flood prevention.