Study On The Reasonable Supporting Time Of Tunnel Secondary Lining

As NATM can effectively use the bearing capacity of surrounding rock so that surrounding rock and supporting structure can work together, can effectively overcome the roof caving and partial landslides and other accidents, and the supporting structure including the initial support and secondary lining, greatly improving the tunnel waterproof effect and the safety stock, therefore has been widely applied in the tunnel construction. While the tunnel secondary lining construction is the top priority in the tunnel construction, can be applied to determine the reasonable of second lining for time to give full play to the bearing capacity of surrounding rock, economy and safety of tunnel cavern excavation is of great significance. In this paper, mostly, carrying on the following studies with the tunnel secondary lining applications:①With the current research status, introduce that determine the mechanism of analysis of the tunnel secondary lining supporting time, and the research methods of tunnel secondary lining supporting time, mainly:elastic-plastic analysis method, the measured data analysis method and tunnel model simulation analysis.②In this paper, relying on the zhongliang-mountain tunnel,monitoring measurement peripheral convergence and vault sinking of the tunnel and analysis monitoring measurement data. Mainly to observed the accumulative deformation of peripheral convergence and vault sinking with the tunnel excavation and data convergence.③Using finite element software ANSYS simulates three-dimensional modeling of tunnel excavation, class Ⅲ, Ⅳ and V rock to calculate the deformation of tunnel surrounding rock, mainly to calculate the Horizontal displacement and Vertical displacement of the tunnel, that is the tunnel peripheral convergence and vault sinking. Comparatively analysis the results and monitoring and measurement Results of zhongliang-mountain tunnel. Eventually,come to the results of the best time of the tunnel secondary lining.Results mainly as follows:④the selection of representative Ⅲ level section of surrounding rock, about29days after excavation deformation achieve stability, convergence and deformation data and curve has at this time to apply for the second lining of the tunnel. ②the selection of representative Ⅳ level section of surrounding rock, about32days after excavation deformation achieve stability, convergence and deformation data and curve has at this time to apply for the second lining of the tunnel.③the selection of representative V level section of surrounding rock, about37days after excavation deformation achieve stability, convergence and deformation data and curve has at this time to apply for the second lining of the tunnel.