MODEL TESTS AND NUMERICAL SIMULATIONS OF TUNNELING CONSIDERING EXISTING BUILDING AND TUNNEL

摘要

The behavior of the ground during tunnel excavation is usually investigated conducting model tests where absolute displacement is applied in the boundary of the tunnel periphery or stress around the excavation face is applied.In this research,a new device has been developed not only for applying inner displacement of tunnel but also for allowing the movements of the tunnel itself with satisfying the equilibrium between tunnel and the surrounding ground.With the new device,model tests of tunnel excavation considering an existing tunnel and an existing building are carried out.Non-linear finite element analyses corresponding to the model tests are also conducted using FEMtij-2D software where elastoplastic subloading tij model is used as a constitutive model of soil.It is revealed that in the ground with existing (preceding) tunnel,the earth pressure distribution around the preceding and following tunnels,and ground movements during tunnel excavation depend on the distance and position between the twin tunnels.It is also found that there is a significant effect of tunneling on the existing foundation of building even the tunnel is constructed in deep underground.The numerical analyses perfectly capture the results of the model test in both conditions.