Measurement and analysis of vibrations caused by the movement of underground trains on surrounding buildings and development of vibration isolation system

This work presents results of thorough investigations of vibration propagation from underground trains on Kalugsko-Rigskaja line of Moscow Underground. The main aim of the work is to develop effective countermeasures that reduce both the floor vibration and structure-induced noise inside scheduled closely adjacent residential compound. This compound consist from 6 sections, that are located 15 to 52 m from the tunnels. Field investigations were performed to measure the ground velocity during underground train passes both on the ground surface and on the foundations of existing buildings. Transfer functions from ground to building foundation were calculated based on these measurements and the prediction of vibration inside the building was performed. The main steps of the prediction analysis, that is in conversion from the vibration levels of the ground surface to the vibration levels of the floors are: 1) determination of the vibration reduction at the transition from the ground to the foundation of the residential buildings; 2) determination of the vibration transmission losses through the building constructions; 3) determination of the resonant increase of oscillations in the center of the floor compared the oscillation of its contour. The paper presents calculated and averaged over the time of measurements transmission coefficients of vertical vibrations between the said groups of structural elements. The calculated transfer coefficients can be used to predict vibration levels in similar buildings subjected to underground traffic impact. Further analysis allowed for calculation of structural member vibration velocity calculations that were compared to valid sanitary standards. Vibration reduction measurements were proposed and their efficiency calculated.