THE USE OF SEISMIC REFRACTION AND MULTI-CHANNEL ANALYSIS OF SURFACE WAVES TO OBTAIN P-WAVE AND S-WAVE VELOCITIES FOR THE DESIGN OF WIND TURBINE FOUNDATIONS

The seismic refraction and multi-channel analysis of surface waves (MASW) techniques were used to obtain subsurface p-wave and s-wave velocities for the design of wind turbine foundations at several different wind farm locations including, Alaska, Montana, and Hawaii. Specifically the velocity data was used to calculate dynamic shear modulus and Poisson's ratio for use in providing site specific geotechnical design parameters for the turbine foundations. P-wave velocities were collected from seismic refraction surveys utilizing multiple shot locations for high resolution. Both one-dimensional (1-D) and two dimensional (2-D) MASW seismic data were collected to obtain s-wave velocities. The MASW process utilized common mid point (CMP) cross-correlation gathers of multi-channel and mutli-shot surface waves to provide high resolution 2-D cross sections of the s-wave data. This data was collected with a multiple channel digital seismograph. A general approach to the data collection, processing, along with results from case histories is discussed in this presentation.