Numerical analysis of effect of excavation on underlying existing metro tunnel and deformation control

According to the practice of the excavation of the Xiqing Road Tunnel adjacent to the existing tunnel of the operating Tianjin Metro Line 1, ABAQUS is applied to simulate dynamically the construction process based on the field monitoring data. On this basis, the effects and the effectiveness of the soil reinforcement alongside the existing tunnel, a protection hoop formed by the slab and anti-floating piles and the reverse heap-loading on the track deformation of the existing tunnel are analyzed. It is found out that the above protection measures adopted synthetically can timely and effectively control the uplift of the track in the existing tunnel and ensure the safe operation of metro. Furthermore, the effect law of the different reinforcement parameters on the track deformation of the existing tunnel are studied. The results show that the increase in the different reinforcement parameters can reduce the up lift of the track in the tunnel and the different deformations between the two adjacent boxes of deformation joint, but the reinforcement effect decreases with increase of the parameters; and there exists a reasonable scope of the reinforcement. The results can provide evidence for the optimization of the construction design.