Abstract:

As an extreme case of adjacent construction of underground engineering, closely-attached underpass will cause significant disturbance deformation of the existing structure and directly affect the normal service performance of the structure. Aiming at the freezing excavation underpassing the operating subway station, the structure-stratum dynamic finite element model was established by means of joint simulation and verified by field test. By transforming the existing line irregularity caused by the closely-attached underpass construction into the wheel-rail dynamic excitation and applying it to the simulation model, the dynamic transmission characteristics between the track and the tunnel were calculated and analyzed, and then the evolution process of the station vibration source intensity in the key construction stage was simulated, which can provide theoretical guidance for similar projects. The results show that due to the dynamic transmission distance, the vibration level of the tunnel side wall is lower than that of the track bed, but the response amplitudes of the two are increased in different degrees in the stage of the line irregularity formed by the closely-attached excavation. The vibration source intensity of the subway station is dominated by the dynamic response below 200Hz, in which the main influence frequency band of the irregularity caused by construction is within 40Hz, and the source intensity is positively correlated with the irregularity amplitude between 8-40Hz, while the vibration of the tunnel side wall is amplified within 8Hz.

Key words: subway station, closely-attached underpass, vibration source intensity, dynamic evolution, dynamic finite element