In-Situ measurement of the shear-Velocity in the shallow earth using a portable vibrator (UGE.4518).

Imaging the shallow subsurface of the earth (the upper 20 meters) is of increasing importance both for engineering purposes (e.g. pile driving, tunnel design for the high speed train (HSL)) as well as for environmental purposes (detection of polluted soil, the determination for pathways for pollution transport). A critical parameter is the shear modulus, not only because it is a measure if the (shear) strength of the material but also because it depends sensitively on soil type, the degree of compaction and on water content. It is proposed here to develop a portable system that employs seismic surface waves for measuring the velocity of shear waves and hence the shear modulus in the earth's shallow subsurface. An 1 vibrator will be used to shape seismic surface waves with an optimization method in such a way that the surface waves at the receiver are optimally impulsive. In this way, a method will be developed to automatically measure the propagation velocity of seismic surface waves in a few minutes, and software will be developed to provide extimates in the field of the shear modulus. The method is designed to complement the existing method for measuring the shear modulus using an in-situ probe (Cone Penetration Tests). The research will be carried out in collaboration with the OYO Center of Applied Geosciences (Nieuwegein, The Netherlands) and the Colorado School of Mines (Golden, USA).

Er zijn drie bedrijven bij dit project betrokken.

Prof.dr. R.K. Snieder
Universiteit Utrecht
Fac. Geologie en Geofysica
Postbus 80021
3508 TA Utrecht