Study On Calculation Method And Structure Of Monolithic Track-bed In Metro Shield Tunnel

The thickness of Track bed is a important design parameters which guaranteed adequate strength, stability and crack resistance under train loads.Compared to sleeper-bed, the pattern of load changed that, Monolithic track bed directly under the dynamic load transfer from the rail.Based on the Strength requirements of the track bed and the tunnel structure, to meet the functional requirements and clearance requirements,this paper analysis the bed minimum thickness and structural requirements.Based on the elastic foundation theory and tunnel equivalent stiffness theory, a flexible foundation composite beam analysis model has been build. Based on the damage pyramid theory, local-punching strength under Lateral force of the track has been researched, track bed stress under Stubbs force be calculation and analysis. Based on the finite element method, The control thickness be access overall bed thickness between internal forces. by analysis the bed stress under different thickness conditions, the minimum thickness obtain with the finite element model.The dynamic train load has been accessed according to vehicles-orbit coupling dynamics theory. Based on finite element analysis model, the stress distribution of Road bed and the tunnel structure under dynamic train load. Through establishment of fatigue equation, the Road Bed high stress and fatigue damage and the concrete life has been analysis.The requirements thickness abtained by comparing stress distribution of track under different conditions of tunnel uneven settlement.Reasonable distance of structural joints has got, by 3D finite element analysis of track bed Internal Force under different structural joints conditions.It concluded that, Fatigue is controlling factors of the bed thickness under the train load.Improve the conditions of the tunnel basement and control uneven subsidence is the effective means to control the deformation of Road bed.