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PBA工法利用小导洞洞群技术,施工快捷、灵活、安全。小导洞施工对周边环境干扰小,施工引起的地层沉降相对较小,施工技术成熟,安全性高。本文结合北京地铁7号线磁器口站工程实例,对小导洞开挖施工进行计算机模拟,以期为PBA工法提供地层沉降分析方面的理论支撑。通过对计算结果进行分析比较,可以得出如下结论:在施工过程中合理选择小导洞的开挖顺序,先跳作上层导洞,能够最大限度地减少地层沉降,保障施工及周边建(构)筑物的安全。
PBA method using small lead hole group technology, construction is quick, flexible and safe. Small pilot tunnel construction on the surrounding environment is small, the formation caused by the relative settlement of the ground, construction technology is mature, high safety. In this paper, with the example of Ciqikou Station of Beijing Metro Line 7, the computer simulation of the excavation of the small pilot tunnel is carried out in order to provide theoretical support for the analysis of the formation subsidence for the PBA method. Through the analysis and comparison of the calculation results, we can draw the following conclusions: In the construction process to select a small pilot tunnel excavation sequence, the first jump into the upper pilot tunnel, to minimize the formation subsidence, protection of construction and surrounding construction Building safety.