Research on Excavation Progress of the SecondHole of Tunnel with Small Clearance Distance based on Safety Factor
In this paper,FLAC3D finite difference software has been used to simulate the distribution of plastic zone of surrounding rock of tunnel with small clearance distanceand the variation law of internal force of support between the first tunnel and the second tunnel under different excavation progress of the second tunnel.The safety factor of tunnel lining under different working conditions has been obtained,and the reasonable excavation progress of the second tunnel has been determined.The reliability of the model has been verified by the measured data.The results have shown that with the increase of excavation progress,there is no obvious change in the plastic zone of the first tunnel,the internal force of the successive tunnel support changes significantly,and the safety factor of the successive tunnel support decreases.The reasonable excavation progress of the second tunnel is 2 m.The error range between the measured data and the simulated data is 10%-20%,which verifies that the numerical simulation of the excavation progress of the second tunnel has certain reliability.
small clearance distance tunnelprogress of the second holeFLAC3D simulationsafety factor