高地下水位区地铁工程U型结构的设计方法

为解决天津某地铁出入段线地下水位较高、或受场地限制及某些特殊原因所不允许的降低地下水的路堑工程问题,地下隧道与地上路基连接段采用U型结构通过.针对场地工程地质条件和水文地质特征,同时结合国内多项工程实例,确定该工程U型结构横断面形式,边墙及底板的计算模型,对结构受力、配筋进行分析和计算;对裂缝宽度、抗浮稳定性进行验算;选取基坑围护及地下水控制措施.计算模型边墙按悬臂梁、底板按弹性地基梁选取,结构按最不利荷载组合进行配筋计算;同时采用管井降水+止水帷幕对地下水进行控制.计算及验算结果均满足设计要求,工程措施选择合理,可为同类工程设计提供借鉴和参考.

Design method of subway U-shaped structure in high groundwater level area

In order to solve engineering problems of high groundwater level or unable to reduce the groundwater level due to site restriction and some other special reasons, the author used the U-shaped structure to connect the underground tunnel with the ground subgrade. Based on the geological conditions and hydrogeological characteristics in the study area, and combined with domestic engineering examples, the author determined the U-shaped structure cross-section and calculation model of side wall and bottom board. Then the force and reinforcement were analyzed and calculated, the crack width and anti-floating stability were checked, and foundation pit enclosure and groundwater controlling measurements were selected. Cantilever beam was selected as the calculating model, and bottom board was selected as the elastic foundation beam. The reinforcements were calculated with the most unfavorable load combination. Meanwhile, the groundwater was controlled by tube well precipitation and waterproof curtain. The calculated and checked results could satisfy the design requirements, and engineering measurements are reasonable. This research could provide some reference and instruction for similar engineering design.