大跨度地铁车站初支拱盖法支护参数研究

Research on supporting parameters of primary arch cover method in long-span underground station

以重庆某地铁项目采用初支拱盖法进行暗挖车站施工为背景,通过对初支拱盖法的荷载确定方法、支护结构承载能力计算方法,以及拱盖法的安全评价方法等进行分析研究,结果表明:当地铁车站处于深埋状态时,岩土压力偏低且可控,可采用30～35 cm厚的单层初支拱盖;当地铁车站处于浅埋状态时,岩土压力偏大,宜采用40～50 cm厚的单层初支拱盖;拱盖法应关注拱盖基础的稳定,不仅要采用锚杆甚至锚索等可靠的加固措施,而且局部应采用人工或机械切割等方法开挖,以减少对基础岩体的损伤与破坏。

This paper takes Chongqing underground project using the primary arch cover method at the beginning of the tunneling construction as the background, makes analysis and research on method of determining the load under the primary arch cover method, bearing capacity calculation method for the supporting structure, and the safety evaluation method for arch cover method. It makes conclusions that when the underground station is in a deep tunnel, rock and soil pressure is low and controllable, 30 to 35 cm thick layer of arch cover at the beginning support to be used. When the underground station is in not deep tunnel, the geotechnical rock pressure is relatively high, and the single-layer primary arch cover with a thickness of 40~50 cm to be used. The arch cover method should pay attention to the stability of the arch cover foundation, not only the reliable reinforcement measures such as bolt and even cable should be used, but also the partial excavation methods such as manual or mechanical cutting should be used to reduce the faults and damages to the foundation rock mass.