Low-Frequency Shear Wave Logging in Unconsolidated Formations for Geotechnical Applications

Abstract

There are four kinds of methods used in low-frequency shear wave logging. They are the downhole method, uphole method, cross-hole method, and suspension PS logging. Among these methods, the downhole method is commonly used in Japan. Hundreds of shear wave measurements using the downhole method have been carried out since it was established in the 1970s. Suspension PS logging is a recently developed method in which a nonsymmetric seismic source and two receivers are built into a single probe. Source-to-receiver spacing is 2 and 3 m and the logging frequency ranges from 100 to 1000 Hz. Shear waves generated by the seismic source in the probe are detected with the receivers installed 1 m apart, and the shear wave velocity is calculated from the difference of the arrival time between the two receivers. Because the distance between the two receivers is fixed in the probe and the shear wave source produces a repeatable signal, velocity values obtained by suspension PS logging have less errorsxompared with the other methods. Shear wave velocity measurements have important applications in earthquake engineering. In this paper, shear wave velocity measurements are shown to give a useful indication of soil liquefaction potential and shear moduli that can be used to predict the amplitude of surface soil motions during earthquakes.

Influence of Epistemic Uncertainty in Shear Wave Velocity on Seismic Ground Response Analyses

“…The proper quantification of aleatory variability requires repeated tests at multiple locations to assess the inherent variability and the spatial correlation structure of V S . On the other hand, the proper quantification of epistemic uncertainty can be achieved by repeated tests at the same location (Jamiolkowski 2012) or by the use of different data-processing approaches in the definition of the V S profile (e.g., by means of blind tests; Kaneko et al 1990, Boore and Brown 1998, Brown et al 2002, Bard and SESAME Participants 2004, Cornou et al 2006, Kim et al 2013, Cox et al 2014, Garofalo et al 2016a, or both. The V S measurement techniques considered in this study are DH, CH, and PS tests for the invasive class, and Surface Wave Methods (SWM) for the noninvasive class.…”

Sismique en forage et diagraphies acoustiques

“…En revanche, il existe une adaptation pour le domaine de la géotechnique, le PSSL (PS Suspension Logging) qui est souple. La méthode du PSSL a été initialement développée dans le milieu des années 1970 par des chercheurs de l'Oyo Corporation du Japon (Kaneko et al, 1990)…”

Foreword

“…Although an adaptation is available for the geotechnical field, namely PS suspension logging (PSSL), which involves a flexible tool. The PSSL method was originally developed in the mid-1970s by researchers at Japan's Oyo Corporation (Kaneko et al, 1990) with geophones used as receivers. Today, the companies Robertson Geologing and Geovista have also developed a probe with hydrophones.…”