Abstract:Research purposes:In the construction of the urban railway,more and more thick filling and heavy load railway open cut tunnels have been appearing in the control of factors of urban layout and construction,especially in the mountainous city,open cut tunnels may also be built above the high filling roadbed.The kind of railway open cut tunnel is more complex than common open cut tunnel,the more factors should be considered in design,around the open—cut tunnel for Fengdu land reclamation on the railway line from Chongqing to Lichuan for the engineering prototype,the critical design features including load combination,open—cut tunnel selection,lining stress analysis,internal and external lining critical process,foundation disposing formation,the whole stability,filling construction technology and SO on,are analyzed respectively.
Research conclusions:This paper proposes the double lining design method of outer lining bearing filling load and inner lining reinforcing structure and bearing later load.By means of finite element structure analysis,the key process is determined which inner lining must be exceed after the completion of outer liner and I—period filling,these design measures can ensure the stress safety and structure stability of open cut tunnel,concrete dam and foundation,and the whole and part stability of filling engineering.The method of shear pile on the bottom of open cut tunnel will prevent filling from pushing tunnel is proposed.Filling construction technology is key to ensuring the stability of open cut tunnel and dam,and the construction of concrete dam should control casting temperature and decline heat of hydration. Research achievements have important reference value and significance on the open excavation construction of railway, highway,subway tunnels,especially involving the open cut structure of thick filling,heavy load and deep foundation.