后建上盖物业基坑近接施工对运营车站隧道的影响分析

Analysis on the influence of adjacent construction of foundation pit on the operating station and tunnel

深圳地铁罗宝线后建深大站上盖物业项目基坑近接运营车站、隧道进行施工,该项目后建基坑开挖深度大于运营车站和隧道埋深,基坑开挖深度23.25m,基坑距离运营隧道最近处2.142m。通过基坑和隧道监测数据分析,发现距离基坑最近运营隧道结构顶部沉降和结构侧边水平位移随着基坑开挖、每道支撑施工、基坑封底、拆换撑、基坑侧边回填等关键工序,呈现出先增大后变小的规律,隧道顶部最大沉降为12.7mm,隧道水平变形最大值为18.6mm。后期基坑施工完成隧道变形稳定后,隧道顶部最大沉降为9.3mm,隧道水平变形最大值为17.5mm。通过采取加强车站隧道旁基坑支护结构、车站隧道结构变形自动化监测、调整基坑内支撑位置、快速拆换撑、采用素混凝土填充地下室侧墙与车站隧道之间的空隙等措施,确保了运营车站和隧道的安全。

The foundation pit of the property project of Shenzhen University Station constructed after Shenzhen Metro Luobao Line is constructed close to the operating station and tunnel.The excavation depth of the foundation pit of this project is greater than the buried depth of the operating station and tunnel.The excavation depth of the foundation pit is 23.25m,and the foundation pit is 2.142m away from the nearest operating tunnel.Through the analysis of the monitoring data of the foundation pit and tunnel,it is found that the top settlement and lateral horizontal displacement of the tunnel structure nearest to the foundation pit increase first and then decrease with the key processes such as the excavation of the foundation pit,the construction of each support,the bottom sealing of the foundation pit,the demolition and replacement of bracing,and the backfilling of the side of the foundation pit.The maximum settlement of the top of the tunnel is 12.7mm.The maximum horizontal deformation of the tunnel is 18.6mm.The maximum settlement at the top of the tunnel is 9.3mm and the maximum horizontal deformation is 17.5mm after the tunnel deformation is stabilized after the foundation pit construction in the later stage.In order to ensure the safety of the station and tunnel,some measures are taken,such as strengthening the supporting structure of the foundation pit beside the station tunnel,automatic monitoring of the deformation of the station tunnel structure,adjusting the supporting position in the foundation pit,quickly dismantling and replacing the bracing,and filling the gap between the side wall of the basement and the station tunnel with plain concrete,etc.