下沉式地铁车辆基地防洪排涝设计标准研究

Flood Control and Drainage Design Standards for Sunken Metro Vehicle Base

[目的]下沉式地铁车辆基地是一种特殊空间利用形式的车辆基地,在防洪排涝方面存在较大风险,但国内现有相关规范和标准中尚无针对这方面的规定。因此,需对下沉式车辆基地防洪排涝设计能力进行深入研究,明确规范和标准中的相关内容,为此类项目建设提供设计依据。[方法]以宁波地铁5号线前殷停车场工程为例,分析了现有规范和标准中有关防洪和排水的设计要求,分析了下沉车辆基地的防洪涝设计方案,分别按50年和100年暴雨重现期对下沉基坑内不同区域防洪涝设计方案进行了对比分析。[结果及结论]下沉式车辆基地应采用“可靠的防、排内涝水措施”来满足防洪排涝的基本要求。在防洪涝方面,下沉式车辆基地防洪墙顶高程和出入口路面高程应高于百年洪水位+安全高,同时防洪墙与周边地面的高差应高于100年暴雨重现期下的所在地块内涝水位。在排涝方面,下沉基坑内的盖体屋面区域排水宜遵循“高水高排”的原则,按100年暴雨重现期设计屋面排水能力,通过重力流方式直排至基坑外;坑内敞开区域采用抽排方式,按100年暴雨重现期设计雨水泵站的总排水能力。

[Objective]As a special form of space utilization for vehicle base,sunken metro vehicle base faces greater risk in flood control and drainage.However,currently there are no available specifications and standards in this regard in China.Therefore,it is necessary to conduct in-depth research on the flood control and drainage design capacity of sunken vehicle base,clarify the relevant content in specification and standards to provide design reference for such projects.[Method]Relying on the Qianyin Parking Lot project of Ningbo Metro Line 5,the design requirements in existing specifications and standards for flood control and drainage are analyzed,as well as the flood prevention and control scheme of the sunken vehicle base.The flood control and drainage design schemes for different areas in sunken foundation pit are compared and analyzed according to 50-year and 100-year rainstorm return periods.[Result&Conclusion]The sunken vehicle base should adopt′reliable measures for waterlogging prevention and drainage′to meet the basic requirements in this regard.In terms of flood control,the flood wall top elevation of sunken vehicle base and the pavement elevation at entry/exit should be higher than the 100-year flood level plus the safety height,and the height difference between the flood wall and the surrounding ground should be higher than the plot waterlogged level under 100-year rainstorm return period condition.In terms of drainage,the principle of′high water and high drainage′should be adopted for the drainage of the cover roof area over sunken foundation pit.The roof drainage capacity should be designed according to 100-year rainstorm return period,and the water should be directly discharged out of the foundation pit through gravity flow.The open area in the pit adopts pumping and drainage method,and the total drainage capacity of the rainwater pump station is designed according to 100-year rainstorm return period.