富水地层基坑悬挂降水对邻近建筑物影响研究

Study on the Influence of Hanging Dewatering of Foundation Pit in Water-rich Stratum on Adjacent Buildings

以南京地铁7号线某站为工程实例,基于该站的基坑规模、地质条件及围护方案,研究悬挂降水过程中地铁车站周边建筑物沉降的控制。通过三维降水模拟及理论公式推导得出悬挂降水施工沉降理论值和基坑降水沉降规律,同时,比选了狭长基坑单基坑悬挂降水与分基坑悬挂降水的沉降值,发现前者引起周边建筑物的沉降比后者大15%~20%。另外,对现场降水试验及施工回灌后各建筑物沉降监测点记录值进行分析,结果表明:在长江漫滩地区基坑内施工降水会引起基坑外各含水层的水位显著下降,而采用回灌对坑外各含水层水头进行补偿是控制周边环境影响的关键。综上研究,针对位于长江漫滩地区,具有周边环境复杂、基坑体量大、岩面深等情况的工程,该方法具有较好的经济可行性,能对周边环境起到较好的保护效果,为今后类似工程提供思路。

Taking a station of Nanjing Metro Line 7 as an example,based on its enclosure scheme,complex surrounding environment and sensitive geological conditions,the research studies how to control the settlement of surrounding buildings of metro station.Through 3D analysis and theoretical formula derivation,the theoretical settlement value of surrounding buildings and the rule of settlement is obtained.It is found that the settlement values of surrounding buildings caused by the narrow foundation pit dewatering are 15%to 20%higher than those caused by piecemeal foundation pit.Through analyzing the record value of building settlement monitoring point after the field dewatering experiment and construction recharge,it is showed that the water level of each aquifer outside the foundation pit decreases significantly and using reinjection well to compensate water head is the key of controlling the settlement of surrounding buildings.In view of the complex surrounding environment,large foundation pit and deep rock face in the Yangtze River floodplain area,the method adopted in this project has better economic feasibility and better effect on the surrounding environment protection,it can provide ideas for similar projects in the future.