零间距下穿既有在建隧道施工技术研究

Study on the Construction Technology for a Newly-built Tunnel Approaching an Existing Station

新建地铁隧道零间距下穿既有隧道在国内外工程中越来越多,由于两条隧道超近距离的开挖施工,会使得交叠区围岩的稳定性大为降低,即使下部隧道开挖引起小范围的坍塌、冒顶也可能诱发两条隧道交叠区之间围岩大范围的冒顶坍塌,严重威胁上部隧道的运营安全及下部隧道的施工安全。如何通过研究交叠隧道间的相互作用以及新建隧道爆破的振动控制技术,保证新线隧道和既有隧道的安全是该类工程的核心目标,同时也是工程的难点所在。围绕这一核心目标,以青岛地铁2号线和3号线李村交叠段为工程背景,采用正交数值模拟试验和理论分析相结合的方法,对零间距交叠隧道稳定控制有关的地层和衬砌变形规律及其控制措施和施工方法优化等问题作了较系统的研究。

The newly-buih subway tunnel approaching the existing tunnel is increasing both at home and abroad. Because the excavation between two tunnels is in a short-distance, it will greatly reduce the stability of the surrounding rock in over- lapping area, and even the small scale of collapse and roof caving from the lower tunnel excavation may also induce large scale of roof caving and collapse of surrounding rock in overlapping area, which will seriously threaten the operating safety of the tunnel＇ s upper part and the construction safety of the tunnel＇ s lower part. By studying the interaction between the overlapping tunnels and the vibration blasting control technology of newly-built tunnel, we find that how to guarantee the safety of the newly-built tunnel and the existing tunnel is the key and difficulty of the project. Focusing on the core goal, this paper took the overlapping section of Lieun between Qingdao Metro Line 2 and Line 3 as the engineering background, combining with the orthogonal numerical simulation experiment and theoretical analysis, it made a systematic study on the strata and lining deformation rules regarding the stability control of overlapping tunnels. Besides, its control measures and optimization of construction methods were studied systematically.