The Numerical Simulation Of Mechanical Characteristics Of The Concrete-filled Steel Tube Support System In Loess Highway Tunnel

Primary lining as the main tunnel supporting structure play an important role instabilizing of surrounding rock. The anchor bolt-support is the common primary lining, butthe thickness of sprayed concrete is thin, and the structural strength is weak, so it is difficult toimprove the phenomenon in loess tunnel which large deformation of surrounding rock is hardto convergence. The lack of carrying capacity in primary lining conducts the potential safetyhazard to tunnel construction and operation. Therefore, it has the practical significance tostudy primary lining in loess tunnel.According to the supporting characteristics in loess tunnel, the concrete-filled steel tubesupport system come up. The new support system consist of hollow steel tube, concrete-filledsteel tube and concrete. The concrete-filled steel tube support system as primary lining willincrease the lining support capacity by adding thickness, reduce the construction disturbance,save the natural strength of surrounding rock in great extent and strictly control thedeformation of surrounding rock. This paper using assuming resistance method and numericalsimulation method, analyzed the economy, effect of support, security of structure,deformation of surrounding rock and structure stress in the process of excavation.Compare the concrete-filled steel tube support system with the anchor bolt-support fromtwo aspects about economy and effect of support. Make a conclusion about what a kind ofsupport form is the best and evaluate it.By assuming resistance method, count the internal force of the concrete-filled steel tubesupport system, and calculate its structure safety.Applying the MIDAS/GTS to establish the3D simulation model, in view of the differenttunnel construction method, the circular excavation method and the CD method, mainly studythe surrounding rock deformation and force of the supporting structure itself and reflect thespace effect in the tunnel construction process.All the research results show that the concrete-filled steel tube support system is a safety,stable and economic new form of primary support.