Characteristics and evaluation of building indoor ground-borne noise pollution induced by subway in Beijing

Combined with Measurement method of ground-borne noise arising from urban rail transit (underground) (HJ 793-2016), Emission standard for community noise (GB 22337-2008) and Standard for limit and measuring method of building vibration and secondary noise caused by urban rail transit (JGJ/T 170-2009), using L_Aeq200, L_{Aeq20 k} and sound pressure level in octave bands as evaluation indexes, the indoor ground-borne noise induced by subway in the nearby buildings was monitored and evaluated, with an experimental study in Beijing. The results showed that the frequency range of building indoor ground-borne noise caused by subway was 12.5-200 Hz in Beijing, and L_{Aeq20 k} was not suitable for the evaluation of low frequency ground-borne noise induced by subway. The characteristics frequency of indoor ground-borne noise of the two subway lines in Beijing was 31.5, 40, 50, 63 and 100 Hz respectively, with 40 Hz as the main frequency. The sound pressure increment on the characteristic frequency was obvious during subway pass, which was the characteristic of subway ground-borne noise pollution. The measured results showed that due to the difference of the energy distribution in the lower part of the subway ground-borne noise below 200 Hz, as well as the difference of A-weighted reduction to low frequency sound pressure level, the L_Aeq200 evaluation results could not objectively reflect the actual effect of subway ground-borne noise. The low-rise buildings had amplification effect on ground-borne noise induced by subway, but the high-rise buildings had certain attenuation. Compared with horizontal distance, the weight of the building and the depth of subway tunnel had a significant effect on the ground-borne noise attenuation. The depth of subway tunnel in subway construction should be considered especially, and the subway should avoid through the low-rise buildings and cottage area in order to control the ground-borne noise pollution.