本文以贵安新区浅埋软岩特大断面隧道项目为工程背景，在兼顾安全性和工期要求的前提下，提出了CD法与台阶法相结合新型隧道施工工艺。根据[BQ]值对隧道围岩进行岩体质量分级计算，得出该施工段应考虑按Ⅴ级围岩进行施工设计；利用FLAC3D软件对CD法和CD法与台阶法相结合的新方法进行围岩稳定性数值模拟，结果表明，相比于CD法，新方法对围岩变形的影响更小，这说明该新方法更有利于保持围岩稳定；通过对新方法开挖过程中的围岩监测表明，隧道两帮水平收敛和拱顶下沉量均在控制目标以内，这说明隧道开挖后围岩和初期支护结构处于安全状态。此种新型施工方法已在贵安新区浅埋软岩特大断面隧道项目中成功应用，施工结果可为其他相关工程，如隧道工程、地下空间工程提供参考，具有一定的实用价值。
This paper takes the shallow-buried soft rock super-large section tunnel project in Gui’an New Area as the engineering background. The new tunnel construction technology combining CD method and bench method is proposed creatively, under the premise of taking into account the safety and construction period requirements. Firstly, the rock mass quality classification of the surrounding rock of the tunnel is calculated according to the [BQ] value. It is concluded that the construction section should be constructed according to the V-class surrounding rock. Secondly, the CD method and a new method combined the CD method with the bench method are used to simulate the surrounding rock stability value based on the FLAC3D software. The results show that compared with the CD method, the new method has less influence on the surrounding rock, which indicates that the new method is more conducive to maintaining the stability of the surrounding rock. Finally, the horizontal convergence of the two gangs and the amount of collapse of the arch are within the control target through the monitoring of surrounding rock during the excavation of the new method, which indicates that the surrounding rock and the initial supporting structure are in a safe state after tunnel excavation. This new construction method has been successfully applied in the shallow-buried soft rock super-large tunnel project in Gui’an New Area. The construction results can provide reference for other related projects, such as tunnel engineering and underground space engineering, and have certain practical guiding significance.
