长江漫滩抽水试验与水文地质参数计算

Pumping test and hydrogeological parameter calculation of floodplain in the Yangtze River

长江漫滩地区第四系是一个巨厚的复杂含水体,地下水丰富,对深大基坑施工影响极大。南京梅子洲过江通道连接线及青奥轴线地下交通系统工程位于长江下游漫滩,基坑最大开挖深度为27.5m。为满足基坑降水设计及施工要求,勘察时选择有代表性的地段布置了3组抽水试验井,对潜水含水层及承压水含水层进行抽水试验,根据试验井类型和边界条件,选用潜水完整井稳定流、承压水完整井稳定流及非稳定流、承压水非完整井稳定流及非稳定流等多种地下水计算模型进行参数计算并综合分析,为设计提供水文地质参数,并实地验证了参数的合理性。

The Quaternary system in the floodplain area of the Yangtze River is a huge and complicated water body with abundant groundwater, which has a great influence on the construction of deep and large foundation pits. The underground transportation system project of the Meizizhou River-Crossing Channel Connection Line and the Youth Olympic Axis in Nanjing is located in the floodplain of the lower reaches of the Yangtze River, and the maximum excavation depth of the foundation pit is 27.5 m. In order to meet the design and construction requirements of the foundation pit dewatering, three sets of pumping test wells were arranged in representative sections, and the phreatic aquifers and confined aquifers were tested. According to the types of test wells and the boundary conditions, various groundwater calculation models, such as phreatic complete well steady flow, confined water complete well steady flow and unsteady flow, confined water non-complete well steady flow and unsteady flow were selected and used to calculate the parameters, and through comprehensive analysis, hydrogeological parameters were provided for design. The later stage of foundation pit precipitation can meet the construction requirements, which has verified the validity of the parameters.