Vibroseismic Survey, High Reynolds Number Tunnel Site, Arnold Engineering Development Center, Arnold Air Force Station, Tennessee

The results of the vibroseismic survey at the proposed High Reynolds Number Tunnel HIRT site indicated that three subsurface zones existed. The near-surface zone ranged in compression-wave velocity from 2170 to 2500 fps 660 to 760 ms to a maximum depth of 10.7 ft 3.3 m. The second zone exhibited velocities from 2950 to 5130 fps 900 to 1560 ms to a depth of 48 to 92 ft 15 to 28 m. Below this zone limestone bedrock was encountered that ranged in velocity from 14,300 to 21,000 fps 4360 to 6400 ms. Shear-wave velocities varied from 700 fps 215 ms at 11.2 ft 3.4 m to 1000 fps 305 ms at 40.0 ft 12.2 m. The shear moduli ranged from 10,000 to 20,000 psi 705 to 1410 kg square centimeters at 11.2 and 40.0 ft 3.4 and 12.2 m, respectively. Compression moduli were about three times the shear moduli for corresponding depths. Poissons ratios generally ranged from 0.45 to 0.47. Shear and compression moduli generally increased with depth.