Dear colleagues

I would like to have your kind opinions on the issue that concerns rock mechanics and geophysics in relation to it, for a very specific problem I have.

I have attempted to find a range in the Barton’s graph (Barton 1995), for Qc vs Vp, which applies to the rock masses which I study (those of Doha, Qatar). However, I only have data from MASW geophysical surveys, which yield only Vs.

Hence, I looked for a way to convert Vs values range into a Vp range. I came to discover that there is a very active Nigerian scientific community which deals with geophysical research at their home turf. So I came across the below expression

ni(poisson) = [(Vp/Vs)^2 - 2]/[2(Vp/Vs)^2 - 2]

from which Vp can be obtained from Vs, with a known Poisson’s ratio. The formula is from a paper by Atat et al. (2012).

Qatari rock masses are sedimentary limestone and dolomite soft to medium hard rock masses situated in a very flat terrain (so there is no need for obtaining Vp, I suppose), and in the above paper, the Authors have used the formula on sedimentary shale layers of Niger delta.

Would you use this formula without reservation, for Vs to Vp conversion, regardless of rock (mass) type?

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