在暗挖法隧道施工过程中,为了保证开挖面的稳定,开挖之前需要进行降水。常规的管井降水技术中,过滤层是开挖之后再采用透水性较好的材料进行回填,对于地质条件为强风化花岗岩,会造成一定程度的浪费。在总结常规管井降水施工工艺的基础上,对常规管井降水技术进行改进,将管井周围土体直接作为透水性材料,通过高压风自动形成反滤层,形成新的降水技术,新技术减少了过滤层包裹和反滤层回填2 道工序。将该降水技术应用于厦门地铁4 号线暗挖隧道施工中,通过测算,单孔可节约过滤料 2. 92 m3,节约施工时间10 h 左右,同时对周围环境污染较小,环保效果突出。

In order to guarantee the stability of excavation surface of mined tunnel, dewatering should be carried out before excavation. The filter layer used in conventional tube well dewatering technology is backfilled by permeable materials after excavation, which would lead to waste for weathered granite. As a result, the conventional tube well dewatering technology is improved. The soil around the tube well is directly used as the permeable materials, and the inverted filter is formed automatically by high-pressure wind, forming a new dewatering technology, which reduces the processes of filter layer wrapping and filter layer backfilling. The dewatering technology is applied to the underground tunnel construction of Xiamen Metro Line 4. According to the calculation results, 2. 92 m3 per hole of filter material can be saved and about 10 h of construction time can be reduced. The pollution to the surrounding environment is small and the environmental protection effect is outstanding as well.