PNNL

Abstract

Downhole seismic testing is one field test that is commonly used to determine compression-wave (P) and shear-wave (S) velocity profiles in geotechnical earthquake engineering investigations. These profiles are required input in evaluations of the responses to earthquake shaking of geotechnical sites and structures at these sites. In the past, traditional downhole testing has generally involved profiling in the 30- to 150-m depth range. As the number of field seismic investigations at locations with critical facilities has increased, profiling depths have also increased. An improved downhole test that can be used for wave velocity profiling to depths of 300 to 600 m or more is presented.