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Downhole Geophysics

Downhole geophysics may be performed in one or more open boreholes as part of a geotechnical investigation. Often, the primary quantities of concern are the compression (p-wave) and shear waves (s-wave) values as a function of depth. These two quantities allow engineers to calculate a broad range of values which pertain to the strength of the rock or soil.

Downhole Geophysics thumb

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This method is a variation of the replica rolex seismic refraction method, usually employing a downhole tri-axial geophone and a surface energy source. The energy propagates from the source to the downhole tri-axial geophone, and is then recorded as both p-wave and s-wave.

As downhole geophysics provides detailed layer velocity information, the data is used to evaluate the p-wave and s-wave velocities of the subsurface versus depth. These values are used to help calculate various dynamic moduli for modeling the seismic response of a site, as required for hospitals, schools and other essential structures in California.