高水位山岭TBM隧道常伴随管片接缝渗漏、开裂漏水等结构病害,为解决上述问题并尽可能保护隧道周边地下水环境,提出一种新型TBM隧道排水技术,通过使用可控制排水量的泄压阀来调节隧道排水量并消减管片衬砌背后地下水压力。首先,在福州至长乐机场城际铁路大象山隧道开展现场试验研究,试验结果表明:
当试验段排水孔间距为3 m且泄压阀压力为0时,可有效地将管片衬砌背后水压力降低至静水压力的30%,并将地下水排放量控制在3.144 m3/(d·m)以下。其次,建立水力耦合数值计算模型,引入泄压排水单元,模拟排水管片在拱脚排水孔处安装泄压阀以控制地下水排放量,将数值计算结果与现场试验结果相比较,两者相对误差保持在8%以下。最后,开展参数分析,研究排水孔间距、泄压阀阀门压力对隧道排水量和管片衬砌背后水压力的影响,计算结果表明: 1)当隧道排水孔间距由15 m减小至3
m时,相较于静水压力,仰拱处水压力降低率由40%提高至78%,而排水量由1.284 m3/(d· m)提升至3.362 m3/(d·m)。2)在排水孔间距为3 m的隧道排水口处安装泄压阀,当阀门压力由0逐级增加至800 kPa时,隧道排水量由3.362 m3/(d·m)降低至0.678 m3/(d·m);而作用在管片衬砌的地下水压力反之呈线性增大,其中仰拱处的水压力值变化较为显著,其增长率由0%提升至77%。
Mountain tunnels bored by tunnel boring machines(TBMs)
at high water levels often encounter issues, such as joint leakage and
cracking. Therefore, a novel drainage technology incorporating pressure relief
valves are proposed to address these challenges and protect the surrounding
groundwater environment. This technology aims to control the drainage volume
and reduce groundwater pressure behind tunnel linings. First, a field test is
conducted in the Daxiangshan tunnel on the FuzhouChangle
airport intercity railway. The results indicate that with a drainage hole
spacing of 3 m and the relief valve pressure set to zero, the water pressure
behind the segmental lining can be effectively reduced to 30% of the
hydrostatic pressure. Furthermore, the groundwater drainage volume is
maintained at 3.144 m3/(d·m). Second, a hydraulic coupling numerical
calculation model is established by integrating a pressure relief drainage
unit. Here, a pressurerelief valve is installed in the
arch foot drainage hole. The numerical results are compared with field test
data, maintaining a relative error of less than 8%. Finally, a parameter
analysis is performed to examine the effects of the drainage hole spacing and
relief valve pressure on the tunnel water drainage volume and the water
pressure behind the segmental linings. The findings are as follows: (1)
Reducing the tunnel drainage hole spacing from 15 m to 3 m increases the water
pressure reduction rate at the invert from 40% to 78% and increases the water
drainage volume from 1.284 m3/(d·m) to 3.362 m3/(d·m).
(2) With a drainage hole spacing of 3 m, increasing the valve pressure from 0
to 800 kPa reduces the water drainage volume from 3.362 m3/(d·m) to 0.678 m3/(d·m). Concurrently, the groundwater pressure on the segmental lining
increases linearly, and the water pressure at the invert shows a significant
variation, with the growth rate increasing from 0% to 77%.