Research On The Excavation Method Of Long-span Highway Tunnel Under The Water Conveyance Tunnel Downstream Of The Reservoir

Along with the height of the economic and social development,people's demand for transportation to further improve,our country engineering construction field has entered the new era,facing the engineering problem is more and more complex,not only has higher requirement for our construction technology.In addition to the complex geological conditions in some cities,it is often necessary to traverse many municipal infrastructures.These municipal infrastructures usually relate to the basic life of the people,which puts forward higher requirements on the construction quality.Therefore,it is of great significance to study the construction method under the unfavorable geological conditions in the city.This paper relies on the shenzhen reservoir to Hong Kong phase ii water transmission tunnel project under the eastern transit high-speed connection in shenzhen,and the paper mainly completes the following work:(1)by referring to relevant specifications,engineering materials and literature,we can understand the excavation methods commonly used in tunnel construction at present.(2)through the shenzhen east transit port expressway connecting line project,the second phase of the water conveyance tunnel data research,analysis of the engineering characteristics of the surface settlement shall not be more than 42 mm requirement in the tunnel construction.(3)the influencing factors of existing water conveyance tunnel under new highway tunnel are analyzed.It includes two-lane highway tunnels with different net distance,two-lane highway tunnels with different buried depth and water tunnel under different geological conditions.(4)on the basis of the existing survey data to wear under the new highway tunnel construction period of high density resistivity method detection,understand the tunnel surrounding rock geological the rich water circumstance,provide the geological conditions of reference to the research of excavation method.By using MIDAS GTS finite element simulation software,numerical simulation was carried out for different excavation methods.Through comparison and analysis of different excavation methods,it was suggested to use double-sidewall guide pit method to excavate the underground water tunnel.(5)based on double wall pilot tunnel method of surface subsidence caused by different construction stages and arch sedimentation data analysis,it is important to found in pilot tunnel excavation in the construction,to strengthen the construction phase of the construction monitoring.Field monitoring data also shows that the pilot tunnel excavation in each construction stage,with double wall under pilot tunnel method in the water conveyance tunnel construction,through to strengthen the construction of pilot tunnel in control can well protect the safety of water conveyance tunnel of water supply.