Downhole Seismic tests are performed on soil and rock sites to measure either on-place shear velocity and compression wave velocity profiles of the soil and rock versus depth. Using these measurements it is possible to make calculations of the dynamic soil and rock properties, for earthquake design analyses for structures , liquefaction potential studies, site development and dynamic machine foundation designs. The parameters that can be determined include Poisson’s ratios as well as shear and Young’s modules.
Downhole Seismic investigations are similar to the CH method, but they only require one borehole to provide shear velocity and compressional velocity wave profiles. The DH method uses a wooden beam on the surface to generate shear and compressional waves. A pair of three component geophone receivers, coupled each either, are lowered downhole, spaced 1 meter, to receive the P- and S- wave energy. This method is performed in accordance with ASTM D4428-D4428M-00 Standard Test.
GET IN TOUCH