[关键词]
[摘要]
本文结合北京地铁某线暗挖隧道咬合桩落底式止水帷幕试验工程,研究 PBA 暗挖隧道洞内有限空间条件下,塑性 混凝土与钢筋混凝土咬合桩止水帷幕施工技术可行性,采用解析法、数值模拟、抽水试验等手段验证咬合桩帷幕的止水 效果。结果表明:(1)咬合桩渗透系数 k=1.88×10-6cm/s,满足设计要求,有良好的止水效果;(2)帷幕实施前后稳定涌 水量由 2129m3/d 变为 6.8m3/d,止水效果明显;(3)抽水试验前后外观测井水位标高无明显变化,现场开挖无渗水。研 究成果验证了该技术方案及施工工艺满足工程建设需要,可为今后类似工程的设计和施工提供借鉴。
[Key word]
[Abstract]
The long construction period and the heavy precipitation of the underground excavation project in urban rail transit have a significant impact on protecting urban groundwater resources. Therefore, the cities strictly control the underground water reduction in subway projects by formulating related policies. The waterproof curtain of plastic concrete and reinforced concrete occlusive pile has the advantages of high strength, strong anti-seepage and controllable cost. It has long-term application value in subway waterproof and drainage engineering. This work focuses on water-proof curtain test project of occlusion pile in an underground tunnel in Beijing Metro. In order to further reduce groundwater discharge and effectively protect groundwater resources, the technical feasibility of water-proof curtain of plastic concrete and reinforced concrete occlusion pile under the limited space of the PBA undercut tunnel was analysed and verified. Moreover, the sealing effect of occlusive pile curtain is verified by means of analytical method, numerical simulation and pumping test. The results indicate that the permeability coefficient of occlusal pile is 1.88×10-6cm/s, in agreement with the design requirements. The water-proofing effect of occlusive pile is obvious, and the stable water inflow is reduced from 2129 m3/d to 6.8 m3/d. The verticality of most piles could achieve the control value. There is no distinct difference in the water level elevation of external observation well and no water seepage in the excavation. The research results verify that the technical scheme and construction technology meet the criterion of the project construction, which can provide reference for the design and construction of similar projects in the future.
[中图分类号]
[基金项目]
暗挖车站洞内止水施工工艺研究