Study On The Key Construction Technology Of Shallow And Biased Arch Tunnel In Rainy Area

As a large-span structure pattern, arch tunnel construction is complicated and its construction process is cumbersome. In the rainy mountains, arch tunnel construction in whole weathered bias strata is extremely difficult. Relying on the Ben Long Ping Tunnel of Long Rui Expressway, article combined theoretical, finite element analysis and site monitoring, researched the key construction technology of shallow and biased arch tunnel in rainy area. Article defined instability mechanism, improved rock pressure calculation method and optimized construction program of shallow and biased arch tunnel. Achievements provided practical experience and theoretical guidance for future similar projects construction.The main work is as follows:(1) Proposed the recognition that instability substance of shallow and biased tunnel is slope instability caused by construction disturbance. Transformed shallow and biased arch tunnel stability problems to dependent slope stability problems. Improved unbalanced thrust method in slope stability analysis, established unbalanced thrust computer program that consider arch tunnel excavation, lining structure and the role of rainfall, then provided qualitative parameters for evaluation of tunnel stability. Based on slope instability mechanism caused by rainfall, and considered variation of suction and rock strength weakening by water,article used finite element calculation to analysis dependent slope safety that combined effects by tunnel excavation and rainfall, obtained instability mechanism of shallow and biased arch tunnel that affected by rainfall.(2) Consider design and calculation problems of arch tunnel lining structure and the wall,article compared different rock pressure calculation theory, proposed shallow and biased archtunnel rock pressure calculation method that consider formation thrust. Research improved arch tunnel construction-load model and calculated the lining structure, then compared it with stratum-structure model and monitoring measurement data, obtain an applicability of improved structure-load model. Analyzed the biased force mechanism of arch tunnel wall,and optimized biased arch tunnel construction method and construction process.(3) For the shallow and biased arch tunnel construction method and process problems,based on Ben Ping Tunnel project, used Midas/GTS finite element software to analysis three drift and no-drift construction method, and analyzed first hole program between shallow and deep side. Then obtain one construction method for shallow and biased arch tunnel.(4) Discussion the problem of Digital Tunnel Management System Platform construction, constructed Multivariate Data Collection System in tunnel construction process.Conducted automated monitoring that used geological prediction and monitoring and measurement means for Ben Long Ping Tunnel. It concluded geological radar detection,geological record and excavation verification, tunnel crown settlement and the surrounding convergence, rock pressure, supporting structure internal force, steel arch internal force and so on. Based on real-time monitoring and multiple sources information and then controlled dynamic construction. Providing information sharing for Digital Tunnel Management System Platform.