A development of an unbiased spiral array for MASW data acquisition
Description
Linear arrays are generally used in MASW surveys, and the result is posted at the centre of the geophone array. A question is cast whether there is any bias related to the source offset and direction relative to the linear array. This paper first examines the existence of the biases by a receiver array with variable source and a source array to different receiver locations. A new pattern of geophone array is proposed to attempt to eliminate these biases. It is an omnidirectional, variable offset array with a spiral pattern. Geometrically, there is no uncertainty of the centre of the array. An experimental survey was carried out to compare this spiral array with a linear array centred at the same point. A record by the spiral array can be analysed using conventional MASW software which assumes constant geophone interval. The records are compared in both the time-distance and the frequency-phase velocity domains. The result demonstrates the spiral array delivers comparable dispersion image to the linear array and it assures a more confident array centre location. The spiral array also indicates viability of an MASW array arranged two-dimensionally. This is also a step forward to a 3D MASW.
Notes
Files
AEGC_2023_ID109.pdf
Files
(2.8 MB)
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