济南轨道交通某深基坑降水与回灌数值分析

Numerical Analysis on Dewatering and Recharging of A Deep Foundation Pit of Jinan Railway

基坑降水会改变基坑周围地下水位,进而引起不均匀沉降,影响周围建筑物安全性,实践证明,回灌法是解决此类工程问题的有效手段之一。以济南轨道交通R1线某深基坑降水工程为研究目标,利用Visual Modflow软件分析基坑降水与回灌,分别模拟基坑在止水帷幕与回灌不同工况条件下降水与回灌对周围地下水位与沉降的不同影响效果。仅回灌模拟结果表明:回灌井设在基坑周围10 m处,保持回灌量大于等于抽水量,地下水位控制效果相对较好;回灌结合止水帷幕模拟结果表明:回灌量控制在抽水量的2/3左右,回灌井设在基坑周围30 m处,回灌在整个模型区域地下水位控制效果最好,沉降小于0.1 cm。根据模拟结果得出适用于该工程地下水位扰动最小的回灌方式及最优方案,为工程施工提供理论依据与参考。

Change of groundwater level and uneven ground settlement are easily to be caused by foundation pit dewatering,which threaten the safety of surrounding buildings seriously. For practical purposes,the recirculation method has been proved to be one of the effective methods to solve the above engineering problems. The foundation pit dewatering experiment of a deep foundation pit in Jinan railway R1 line was simulated by using the Visual Modflow software under different water stop methods. As to the change of groundwater level and uneven ground settlement used as evaluation index of foundation pit dewatering,the influence of different water stop methods and recirculation methods including waterproof curtain and recirculation on the evaluation index were analyzed respectively. It can be concluded that the groundwater level can be well controlled when the recirculation amount was not less than the pumping amount with the recirculation well 10 m away from the foundation pit. With the combination of recirculation and waterproof curtain,the groundwater level can be well controlled when the recirculation amount was two-thirds of the pumping amount with the recirculation well 30 m away from the foundation pit,and the groundwater settlement was less than 0.1 cm. Furthermore,the optimal recirculation scheme suitable for the deep foundation pit of Ji＇nan railway R1 line was determined,which provided a reference for the similar engineering construction.