Published: Jan 1994
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This overview is presented from a user's point of view and will consider the practical aspects, nature of the problem to be studied, information requirements, their applications and costs involved. The discussion also reviews the perceived advantages and limitations of various methodologies with suggestions and needs for future developments. Contributions to this symposium are also discussed within the above framework. The comments given are those of the writer and are based on reported research, and personal experiences and perceptions.
Conclusions suggest that most field seismic tests are quite capable to measure the low strain, shear wave velocity profile. However, the testing must rely on other tests to provide ground truthing and identify stratigraphy, except for the downhole seismic cone penetration test where the seismic sensor was added to a tool primarily used for stratigraphic logging. It is recommended that since the downhole seismic method for the cone has evolved into a simple, reliable, cost effective tool, it be added to the ASTM Standard D 3441-86 for cone penetration tests in soil which is currently being revised.
Also, most current field dynamic test methods do not routinely measure the important parameter, material damping. A preliminary procedure for damping measurements with the seismic cone is outlined in this symposium. It is suggested that researchers focus their efforts to measure damping in-situ, compare and scrutinize their results in order to establish an acceptable standard procedure.
It is also apparent that little progress has been made in the in-situ measurement of shear modulus and damping as a function of strain, even though it is generally accepted that such properties are necessary to predict dynamic response of high energy events like earthquakes and should be a high priority for future R and D. It currently appears that the self-boring pressuremeter, a downhole impulse test and a proposed tool reported in this symposium have the best chance of providing such information.
Geotechnical, Field, Seismic, Dynamic, Site investigation, Applications, Shear wave velocity, Strain level, Damping
Professor, The University of British Columbia, Vancouver, B.C.