Theoretical Analysis on the Effectiveness of Pipe Roofs in Shallow Tunnels

When a pipe roof is used as pre-support for the surrounding rock in shallowly buried tunnel, accurate prediction of support effectiveness important order to ensure rationality structure design. Based on analysis effects, considering construction time structures and interaction mechanisms between steel pipes rock, we establish calculation model pressure acting each semi-circular boundary. Through comparison with measured results, demonstrate that stress deformation are reasonable. According coordination conditions boundary alongside Peck formula, theoretical method based indexes ground loss rate, settlement trough width, maximum surface settlement, thereby realizing quantitative evaluation pipe-roof effectiveness. At same time, effects diameter, circumferential spacing, excavation footage length analyzed. The conclusions can be basis design optimization roofs guide application roofs.