A critical insight into the influence of data acquisition parameters on the dispersion imaging in passive roadside MASW survey

Abstract

Passive roadside method of multichannel analysis of surface wave (MASW) is a simple passive technique of subsurface exploration that can provide deeper subsoil investigation compared to conventional active MASW technique. However, attributed to the lack of thorough experimental validation with other techniques and establishment of various acquisition parameters, the number of real world applications of the method is scanty. The paper presents the results of extensive experimentation to highlight the importance of two primary acquisition parameters, namely the length of receiver array and acquisition time, on the dispersion imaging of roadside survey at sites comprising different traffic volume. The length of receiver array directly affects the resolution of dispersion image and the estimated depth of shear-wave velocity profile. Thicker energy band and poor resolution in the lower frequency band of dispersion image are found to be the outcome of utilizing smaller arrays. The span of acquisition time is a site dependent parameter and is governed by the volume of the traffic and number of existing sources on the road surface nearby the test site. Comparatively smaller recording time is found effective in producing dispersion images with sufficient resolution in a heavier traffic volume case. The paper also illustrates a detailed comparison of results obtained from roadside and active survey in terms of the dispersion imaging and shear wave velocity profiles at the specific sites.