Abstract
This paper presents a novel fast analysis of wave speed (FAWS) algorithm from the waveforms recorded by a random-spaced geophone array based on a compressive sensing (CS) platform. Rayleigh-type seismic surface wave testing is excited by a hammer source and conducted to develop the phase velocity characteristics of the subsoil layers in Shenyang Metro line 9. Data are filtered by a bandpass filter bank to pursue the dispersive profiles of phase velocity at various frequencies. The Rayleigh-type surface-wave dispersion curve for the soil layers at each frequency is conducted by the ℓ1-norm minimization algorithm of CS theory. The traditional frequency-wavenumber transform technique and in-site downhole observation are employed as the comparison of the proposed technique. The experimental results indicate the proposed FAWS algorithm has a good agreement with both the results of conventional even-spaced geophone array and the in-site measurements, which provides an effective and efficient way for accurate non-destructive evaluation of the surface wave dispersion curve of the soil.
Highlights
In recent decades, with rapid urban population growth, underground constructions which extend human activities into underground spaces have attracted increasing attention [1,2]
The processing is performed with the optimized picking of the frequency-wavenumber spectral maxima by the1 -norm minimization algorithm, which is transformed to the dispersion curve of surface wave velocity
A real-world experiment was employed to study the effectiveness of the proposed Fast Analysis of Wave Speed (FAWS)
Summary
With rapid urban population growth, underground constructions which extend human activities into underground spaces have attracted increasing attention [1,2]. A metro system is a kind of underground construction in an urban region to perfect alternative transportation in order to overcome traffic congestion, road accidents and environmental pollution caused by vehicles in the modern international metropolis [2,3]. A metro project faces significant challenges of construction for the complex conditions, e.g., soft soil layers, interaction caused by the urban infrastructures, vibration issues, accidents during the construction phase, etc. The constant need to improve the operational safety of construction has driven the development of non-destructive evaluation techniques and in-site monitoring methods aimed at the ongoing assessment of the metro rail corridors and near-surface soil layers [5,6]. The most important step of the underground construction in geotechnical evaluation is in situ identification of soil properties. The soil is a kind of multiphase, particulate medium with complex
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