强渗透地区地铁降水回灌方案研究

Study on subway dewatering reinjection scheme in high permeability area

地铁基坑降水的直接外排造成地下水资源的极大浪费,资源性回灌是解决施工排水综合利用的有效途径。以强渗透性地区地铁基坑降水工程为例,研究基坑降水的资源性回灌方案。分析区域水文地质条件,提出地铁降水的回灌方案,构建地下水流数值模型,评价回灌方案的可行性,定量评价井间距对回灌水位的影响和回灌对降水区的影响。结果表明:设计的回灌方案能够实现基坑降水的全部资源性回灌;井间距南北向由10 m增加至100 m时,回灌区水位下降1.5 m,即增大井间距可使回灌区水位上升幅度减小;井回灌使降水区局部地区水位抬升4~6 m。

Direct discharge of dewatering from subway foundation pit causes a great waste of groundwater resources.Reinjection is an effective way for comprehensive utilization of water resources.Taking the subway foundation pit dewatering project in high permeability area as an example,this research studies the resource recharge scheme of foundation pit dewatering,analyzes the regional hydrogeological conditions,constructs groundwater flow numerical models,puts forward and conducts feasibility evaluation of a reinjection scheme.Quantitative evaluation is also carried out of the effects of well spacing on recharge water level and the impact of reinjection on dewatering area.The results show that the reinjection scheme can realize all resource reinjection of foundation pit dewatering.When the well spacing increases from 10 m to 100 m in the north-south direction,the water level in the reinjection area decreases by 1.5 m,indicating increase in the well spacing can reduce the rise of water level in the reinjection area.The reinjection can raise the water level in some dewatering areas by 4 to 6 meters.