In situ Measurement and Analysis of Subway Vibration’s Transmission and the Influence to Nearby Buildings

Abstract:

The three dimensional environmental vibrations induced by a shallow buried subway in Shanghai were in situ measured. By applying with continuous wavelet transform and 1/3 octave frequency vibration level, the vibration transferring characteristics between the tunnel and the open field were analyzed. Simultaneously to the human comfort inside a nearby six story residential building. Testing results include 4 aspects: ① the 3 D vibrations on rail pads were characterized by wide banded and shocking. The vertical and transverse vibrations were relatively smooth after transferred to the center of lining, but amplitudes attenuated greatly. ② The 3 D vibrations in the open field transferred from lining were obviously shocking vibration characteristics corresponding to the carriages. The frequencies were the same with the lining, but the amplitudes attenuated smaller, sometimes maybe magnified. ③ After transferred through the third filter system represented by the masonry walls of building, the vertical resonance frequencies of floor slabs were corresponding to the peak values of the vertical octave vibration levels in this testing, and were the main factor influencing the human comfort inside building. ④ The horizontal high frequencies transferred from subway tunnel have potential influences on some floors’ human comfort, need to be paid more attentions. The above measurements will be benefited to the design of vibration reduction methods to railway vibrations specifically.

Key words:subway; environmental vibration; wavelet analysis; frequency vibration level; human comfort