Study On Construction Technology Of Multi-arch Tunnel Under Complex Urban Conditions

The mountain-shaped and topography of China occuping a relatively large area,it is prerequisite to construct highway tunnels to make the transportation network between city and mountain areas more complete.The highway tunnels connecting city and mountain areas are more and more widely applied due to that multi-arch tunnels have many merits in the connection mode of the bridges and tunnels and the occupied.In recent years,because of the rpaid development of urban transportation network,the development space of groud transportation is limited.On the contrary,the underground transportation is getting better and better,especially multi-arch tunnels in urban highway tunnels are highly favored as the Chinese tunnel construction technology becomes more and more mature.However,there are still many shortcomings in the construction experience of multi-arch tunnels,and it is extremely obvious that ones which is constructed in some complex conditions.As a result,it is necessary to have a further study in the technology of multi-arch tunnels in some special environmental conditions.Based on the research background of Changbin Road multi-arch tunnel exit in the main section of the southern section of Jialingjiang Bridge Tunnel Project in Chongqing Zengjiayan,this paper has carried out certain construction techniques based on the project through theoretical analysis,finit element numerical simulation,on-site monitoring and measurement analysis.It aims to solve the construction difficulties of relying on the project and provide a certain reference for the construction of similar multi-arch tunnels.The main contents are as follows.(1)Summarizing the common excavation methods and merits and dismerits of multi-arch tunnels,analyzing the excavation methods and supporting measures adopted by the supporting project.(2)Concluding the changing laws of stress and displacement of surrounding rock,through simulating the three-dimensional numeric of the unconventional "asymmetric three-guided tunnel method" and the conventional three-guided tunnel method is forced to rely on the project due to the construction conditions.Through practicing and comparing analysis of three-dimensional numerical simulation,it is proved that the construction based on the "asymmetric three-lead tunnel" method is feasible and successful.(3)Comparative analysis of the "asymmetric three-guided tunnel method" and conventional three-guided tunnel method construction on the slope above the tunnel,from the impact on slope displacement,principal stress,shear stress,plastic zone four aspects of analysis,conventional three Guide hole method is better than "asymmetric three guide hole method".However,from the analysis of economical and practical conditions,the construction of the "asymmetric three-lead tunnel method" is the best,and this method can ensure the stability of the slope.(4)Summarizing the commonly used advanced geological prediction methods for tunnels,analyzing the principles,equipment and detection methods of TRT6000 advanced geological prediction,and using TRT6000 to analyze and analyze the advanced geological prediction of supporting projects.(5)Conducing on-site monitoring and measurement of the deformation in the tunnel and ground surface of the supporting double-arch tunnel,analyzing the deformation law and deformation trend,and comparing the monitoring results with the numerical simulation calculation results to further verify that the relying project uses unconventional "asymmetric" The rationality of the construction of "excavating three-guided tunnel method".