In situ shear wave velocity from MASW surface waves at Norwegian soft clay sites.

The Multichannel Analysis of Surface Waves (MASW) technique, used to determine shear wave velocity (Vx) and hence small strain stiffness (Gmax), has recently generated considerable interest in the geophysics community. This is because of the ease of carrying out the test and analysis of the data. The objective of this work was to assess the repeatability, accuracy and reliability of MASW surface wave measurements for use in engineering studies. Tests were carried out at 5 well-characterized Norwegian soft clay research sites where Vs had already been assessed using independent means. As well as being easy and quick to use MASW gave consistent and repeatable results. The MASW Vs profiles were similar to those obtained from other techniques. This work also confirms that MASW Vs clay profiles are comparable to those obtained by correlation with CPT. For these sites there also seems to be a good correlation between normalized small strain shear modulus and in situ void ratio or water content and the data fit well with published correlations for clays.