Ambient noise in the urban environments is usually generated from fixed-location human activities. The noise sources are not random and uniformly distributed. When ambient noise are used to extract the subsurface soil properties, the subsurface shear-wave velocities may be overestimated since they are inverted from the apparent dispersion curves. Thus, angle correction must be applied on the dispersion curve before inverting for the subsurface shear-wave velocity model. Beamforming is a commonly used technique to estimate the direction and velocity of propagation of the ambient noise recorded by the vertical component of the geophones. However, no studies about the application of beamforming on the ambient noise recorded by DAS have been published. Due to the measurement of DAS, amplitude projection and polarity reversal may occur in the ambient noise recordings, which may lead to unreliability of the beamforming results. To compare the two acquisition methods, we model the ambient noise recorded by geophone and DAS. MUSIC beamforming is applied on several synthetic ambient noise data recorded by geophone and DAS in different circumstances to explore the reliability of the beamforming results. Conclusions obtained from the synthetic data tests support the observation on a field data test.
Monday, October 12, 2020
Session Start Time: 1:50 PM
Presentation Time: 2:15 PM
Location: Poster Station 6
Presentation Type: Poster
