富水砂卵石地层超长基坑降水设计优化研究

Study on dewatering design optimization of super long foundation pit in water rich sandy pebble stratum

成都轨道交通17号线明光站—九江北站区间明挖区间基坑所处地层为砂卵石地层,富水性好。在已有的水文地质资料、明挖区间基坑降水施工方案的渗透系数k的条件下,根据干扰井群的叠加原理,利用解析法预测基坑中某一点处的地下水位降深。通过对比分析预测结果与实测结果,发现明挖区间端头盾构吊出井基坑处的地下水位降深不能满足降水要求,从而进一步调整和优化端头井基坑区域的地下水控制方案,并分析总结降水井设计的技术要点,可为砂卵石地层基坑降水设计及施工提供理论依据及实践经验。

The foundation pit between Mingguang station and Jiujiang North Station of Chengdu rail transit line 17 is located in sandy pebble stratum with good water yield.Under the condition of existing hydrogeological data and permeability coefficient k of foundation pit dewatering construction scheme in open excavation section,according to the superposition principle of interference well group,the analytic method is used to predict the drawdown of groundwater level at a certain point in the foundation pit.By comparing the predicted results with the measured results,it is found that the drawdown of groundwater level at the end shield lifted out of the foundation pit of the open excavation section can not meet the dewatering requirements,so as to further adjust and optimize the groundwater control scheme of the end shield pit area,and analyze and summarize the technical points of the dewatering well design.The results of this paper can provide theoretical basis and practical experience for the design and construction of foundation pit dewatering in sandy pebble stratum.