Analysis on the Influence of Foundation Pit Excavation on the Deformation of Adjacent Tunnels

With the continuous development of urban underground space construction, it is a common phenomenon to carry out foundation pit construction adjacent to existing tunnels. Excavation of foundation pit will destroy the original in-situ stress field, and then affect the adjacent tunnel, so it is necessary to study the corresponding measures. Based on this, this paper simplified the tunnel as Timoshenko beam acting on the Pasternak foundation, and established the calculation model of tunnel deformation caused by excavation unloading. Taking the deep foundation pit project of Hefei University City as an engineering case, the Plaxis 3D numerical simulation and theoretical model considering the characteristics of small deformation and strain were used for calculation respectively, and the two results were compared with the field measured data. The results show that the simulation results of Plaxis are basically consistent with the measured results, and the maximum deviation is only 0.5 mm, indicating that the constitutive model considering the characteristics of small deformation and strain can well reflect the stress and deformation of soil; In this paper, the calculated results considering the shear action of the tunnel are in good agreement with the measured results, and the calculated results of the analytical method are closer to the measured results than the simulation results, indicating that the proposed theoretical model can more accurately and effectively analyze the influence of the excavation effect on the deformation of the side-lying metro tunnel.