Ma Baolin, Wu Shengzhi, Chen Qihui, Liang Erbin, Li Xiudong
School of Civil Engineering, Shandong Jianzhu University, Jinan, 250101, Shandong, China.
China Railway 14 Bureau Group Co, Ltd., Jinan, 250000, China.
Sci Rep. 2024 Jun 18;14(1):14024. doi: 10.1038/s41598-024-63921-z.
In the construction of tunnels under existing stations, it is necessary to control their settlement. When there is a pile foundation in the existing station, the pile cutting has a significant impact on the settlement of the existing station. To determine the influence of existing piles on the settlement of subway stations, a reasonable pile-cutting time is proposed. Based on the Chengdu Metro Line 9 underpassing the existing Line 1 hatchery station, the settlement law of the tunnel underpassing the existing Line 1 station is analysed via a numerical simulation. Furthermore, the deformation and stress characteristics of the existing piles, pipe roofs, and tunnel linings and the supporting effect on the existing station are discussed. It is concluded that the cutting of existing piles causes a change in the tunnel bearing system, thus resulting in a certain deformation of the station. The influence of different pile cutting times on the settlement of the existing station is then analysed, and it is clarified that the tunnel support stiffness is significantly enhanced after the construction of the secondary lining. At this time, the settlement of the existing pile station is significantly reduced. Finally, through a field investigation, the effect of surface grouting, pipe shed, and multilayer lining on the settlement control of the existing station while the existing pile foundation exists is determined. This research can provide a reference for the settlement control and foundation underpinning of existing stations at ultra-small distances in underground excavation tunnels.
在既有车站下方进行隧道施工时，有必要控制其沉降。当既有车站存在桩基础时，截桩对既有车站的沉降有显著影响。为确定既有桩对地铁站沉降的影响，提出合理的截桩时间。基于成都地铁9号线下穿既有1号线孵化园站，通过数值模拟分析了下穿既有1号线车站的隧道沉降规律。此外，探讨了既有桩、管棚和隧道衬砌的变形及应力特性以及对既有车站的支护效果。得出结论：既有桩的截断导致隧道承载体系发生变化，从而使车站产生一定变形。接着分析了不同截桩时间对既有车站沉降的影响，阐明二次衬砌施工后隧道支护刚度显著增强，此时既有桩车站的沉降显著减小。最后，通过现场调研，确定了地表注浆、管棚及多层衬砌在既有桩基础存在时对既有车站沉降控制的效果。本研究可为地下开挖隧道中极小间距既有车站的沉降控制及基础托换提供参考。
