Zoning Research of the Engineering Impact of Foundation Pit Excavation on Adjacent Existing Tunnels

Most zoning analyses of the engineering impact of foundation pit excavation on rail transit structures use spatial distance as the primary control factor, while overlooking the effects of rock and soil physical and mechanical properties. In order to divide the engineering influence zones more scientifically, reasonably and precisely, the methods of numerical simulation, dimensional analysis and correlation analysis are adopted to study the foundation pit engineering and adjacent lateral existing tunnel, the engineering impact zoning method is proposed with γH/E and θE/φc as control factors. The results indicate that: The displacement of the lateral tunnel increases progressively with ongoing foundation pit excavation. There is a significant and non-linear relationship between the displacement of lateral tunnel and each variable, which is more accurately described by Spearman correlation coefficient. In the same typical stratum regional environment, it is more scientific and reasonable to use the spatial relation characteristics such as h/H to divide the engineering impact zoning. Under different geotechnical environment, the correlation between tunnel displacement and γH/E, θE/φc is particularly prominent. Using these parameters as control factors and tunnel displacement magnitude as the zoning criterion, a zoning map of the engineering influence of foundation pit excavation on adjacent existing tunnels is proposed.