Special Research Unit on Geophysical Exploration
Imaging and characterization of bearing layers and their geotechnical properties is essential for civil engineering prior to the construction. The unit is engaged in the research on geophysical exploration or field measurement technique to image the subsurface and to evaluate its physical property.
Development of Integrated Geophysical Investigation Technique for Vulnerability Assessment of Levee (Priority Research Project) :
Recent severe flooding disasters occurred in many localities caused by typhoon, hurricane and torrential rainfall have reminded us the importance of vulnerability assessment of levee. Geophysical investigation method is expected to play an important role in the assessment of levee, because the conventional visual monitoring and spot drilling technique is inadequate to detect internal anomalies of levee. Geophysical investigations have been undertaken to establish an integrated geophysical survey method helpful for the assessment of failure vulnerability of earthen levees during flooding or earthquake. Right figure exemplifies a successful result that integrated geophysical surveying detected a high resisitivity or high permeable zone within a levee body.
Detailed Imaging and Modeling of Active Faulting Structure (Strategic Research) :
Active faults which have the potential to cause disastrous earthquake in the near future are widely distributed in Japan. As well known, faulting structure recorded in the near surface layer is the key to reveal the behavioral pattern of each fault and evaluate the potential activity. High-resolution seismic reflection method using Land Streamer developed by PWRI is applied and to be widespread as the standard method to image detailed structure of an active fault.
High-precision Measurement ant Testing Method for Geotechnical Property Evaluation (Ordinary Research) :
Synthetic Log Profiles with Core Test Data for a Hole drilled in the Kanto Plain where thick Holocene sediments are deposited. (ENLARGE)
Recent developments of high sensitive sensors and wide dynamic range digital recording equipments have enabled the high-precision field measurement or laboratory testing in the environmental and engineering fields. A concise sampling technique for soft sediments, reliability improvement of Standard Penetration Test, re-examination of the conventional physical test procedure for soil specimens, and high-precision grain size analysis is to be studied in this research.