A Study On The Stability Of The Surrounding Rock Of Underground Subway Stations For Transfer In Cities

The HongQiHeGou Station of rail transit in the urban area of Chongqing is an undergroundisland cross for light rail line3and subway line6, with the former above the latter. The excavatedsection of the station has four forms: A, B, C and D, belonging to a typically shallow-buried andsuper-large section tunnel, with the minimum thickness of the rock cover8.6m and the ratiobetween depth and span0.4m. But for form B, the maximum section，the width is25.55m, theheight is32.83m and the excavation area is760m2. Since the steps for tunnel excavation arecomplex, the inner cross tunnel portals are frequently seen, the stress transformation betweenprocesses are complicated and the stability of the surrounding rock during the excavation is poor,the project for the tunnel, especially the construction for the cross section of light rail line3andsubway line6can be regarded as the most difficult in Asia.The thesis focuses on the stability of the surrounding rock during the excavation of theHongQiHeGou Station of rail transit in the urban area of Chongqing. What’s more, finite elementsoftwares, Midas/GTS, are applied for stimulation on the study for the surrounding rock and thestress, strain and displacement of its support structure. To be specific, this study aims to address thefollowing research questions:①Theoretically, mechanical properties of the surrounding rock are discussed. Besides,judgment criteria and research methods for the stability of the surrounding rock are explored andsummarized.②By numerical simulation,settlement and stress analysis of the intersection when theexcavation of the double side-hole method and CD method,simulated different conditions,analysissupporting the forces,a relatively reasonable construction method,and achieve technically feasible,economically reasonable and reliable guarantee for security;③The mechanical properties of the cross position,stability analysis of surrounding rock andthe settlement amount of variation on the intersection of the construction process,cross theintersection after excavation,analysis of cross-section of different effects for2m excavation and3m excavation;④Analysis of data for monitoring and measurement at the cross-section,analysis of effects forcrown settlement and spandrel settlement and horizontal convergence,and to explore the long-spantunnel in the cross-section of the deformation law.