Study on TBM launching in parallel with small spacing

摘要

The launching of TBM (tunnel boring machine)is very important in the tunnel construction procedure, which is also of great risk. Water and slurry may burst into the shield work well in case of inappropriate launching process, resulting in the collapse of work well. Generally, one work well of tunnel station is uniquely designed for one TBM. The condition that two tunnels or more share one shield work well is rare. Based on tunnel construction project of metro line 1 in Hangzhou, the special problem of TBM launching from one work well which had three tunnels in parallel was studied. The minimum spacing between tunnels is 1.83m, which is only approximately 1/3 of the diameter of tunnel. The most dangerous situation of middle TBM launching was studied, which had great influence on two existing side tunnels. Finite element program was adopted to simulate the grouting reinforcement around the side tunnels. The stresses and displacements of two side tunnels during the middle tunnel launching progress were studied. The effects of grouting reinforcement and different reinforcement regions were compared to guide the reinforcement construction. By real-time monitoring of the displacement of side tunnels and ground settlement, the grouting reinforcement and TBM operation measures were modified and adjusted, insuring the successful launching of TBM.