Geotechnical Use Of A Shear-Wave Vibrator: In-Situ Measurement Of Nonlinear Properties Of The Ground Surface

A new method is proposed for evaluating non-linear properties or strong motion<br>responses of the soIt ground directly in the field. The method utilizes a shear-wave<br>vibrator, which has been conventionally used for the reflection survey in the resources<br>exploration, as an artificial strong motion source. Various types of cones, such as<br>seismic cones and electrical cones, penetrated into the near surface are used to monitor<br>the ground response to the vibration. Field tests for the method were performed at the<br>Tone River Site near Sawara City, approximately 60km northeast of Tokyo. The tests<br>showed the shear-wave vibrator had a power to oscillate the ground with lOOgal or<br>more at 5m from the vibrator baseplate. Decrease in shear wave velocity was clearly<br>observed with increasing vibration level, which means non-linearity of the shear<br>modulus of the ground is detectable in place by this method.