Events

Abstract: The linear and mildly nonlinear dynamic properties of basalt rock from the Idaho National Laboratory, USA, were investigated in this study. Two types of basalt rock were tested: (1) vesicular basalt which had some voids, and (2) aphanitic basalt which had almost no voids. The combined resonant column and torsional shear (RCTS) device was employed to evaluate the shear wave velocity (Vs), the shear modulus (G) and the material damping ratio in shear (D) of the rock over shearing strains ranging from about 10-5% to 0.02%. The elastic threshold shear strain ( ) for basalt specimens ranged from about 10-3% to 10-2%. The linear dynamic properties (VS, Gmax, and Dmin) and nonlinear dynamic properties (G/Gmax - log and D - log curves) exhibited little change with confining pressure. The minimum value of G/Gmax was 0.84 at = 0.014%. On the other hand, the maximum value of D was 2.12 % at = 0.013%. As a simple geotechnical engineering comparison, the nonlinear curves of basalt and sand are compared. Also, it is important to note that both solid and hollow specimens of basalt were tested.

Bio: Kenneth  H  Stokoe,  II  has  been  working  in  the  areas  of  field  seismic measurements, dynamic laboratory  measure than  50  years.  He  has  been instrumental in developing several small-strain field seismic methods for in-situ shear wave velocity measurements and recently a large strain method for nonlinear measurements of shear wave velocity. He has also developed two types of resonant column systems (fixed-free and free-free) that are used to evaluate dynamic soil and rock properties in the laboratory. Over the last  33  years,  Dr.  Stokoe  has  led  the  development  of  large-scale mobile  field equipment  for  dynamic  loading  of geotechnical systems, foundations and structures, an activity that has been funded by the National Science Foundation, first in the NEES program for 20 years and now for 9 years in the NHERI program. The equipment has already led to the development  of  new  testing  methods  to  evaluate  soil  nonlinearity and liquefaction  
directly  in  the  field.  Dr.  Stokoe  has received  several  honors  and  awards, including  
election to the National Academy of Engineering, the  Harold  Mooney Award from the  
Society  of  Exploration  Geophysicists, and the  C.A. Hogentogler Award from the American Society for Testing and Materials, the H. Bolton Seed Medal and the Karl Terzaghi Distinguished Lecturer from the American Society of Civil Engineers, the Bengt Broms Lecture from the Swedish Geotechnical Society, the Geo-Legends Recipient from the ASCE Geo-Institute and the Joe J. King Professional Engineering Achievement Award from the University of Texas.