Seismic Site Characterization Techniques Applied to the NATO RSG-11 Test Site in Muenster Nord, Federal Republic of Germany

摘要

Seismic P and SH wave refraction experiments at the NATO RSG-11 test site in Muenster Nord, Federal Republic of Germany, reveal the presence of a nearly horizontal, three-layer velocity structure. The upper layer, composed of unconsolidated glacial till, is 1 m thick and has P (compressional) and SH (shear-horizontal) wave velocities of 240 and 165 m/s. The second layer, made up of similar, more compacted material, is 9.5 m thick, with a P wave velocity of 470 m/s and an SH wave velocity of 275 m/s. The third layer, interpreted as the groundwater table, is located at a depth of 10.5 m and has a P wave velocity of 1590 m/s. The SH wave velocity of this layer is controlled by the matrix material and is the same as that of the second layer. A single, unreversed observation indicated a fourth layer at a depth of about 20 m, but the existence of this layer remains unconfirmed. The observed fundamental mode Love wave dispersion is in agreement with the theoretical dispersion predicted by the refraction velocities. Computed partial derivaties of phase velocity with respect to shear wave velocity show, for the frequencies observed, that the dispersion confirms the thicknesses and velocities of the two upper layers and is not affected by the deeper structure. (Author)