東京都内各所におけるS波の測定結果 : 第1報

概要

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It is apparent that the in situ measurements of the S wave velocities will supply a great deal of new information, which could not be obtained from the current analysis of travel time curves of P waves, for the elucidation of vibration chracteristics of subsoil layers. In view of this fact, seismic surveys by means of SH waves as well as P waves were carried out at 12 places in Tokyo Metropolitan area where the typical subsoil layers such as the clay, sand and other layers are found near the surface. The SH waves were generated by hitting either end of a wooden plate which was firmly pressed on a thin cover of slacked lime cement on the ground by means of a sufficient weight. The results of the observations are shown in Figs. 11 and 12. It will be perceived from Fig. 12, that no much divergence exists in the velocities in the same kind of layers at different localities. So the mean velocities thus calculated can be used as standard values for such layers. They are 96m/s in alluvial clay and 171m/s in alluvial sand respectively. In the same way mean values of the Poisson's ratios are calculated to be 0.44 and 0.49 respectively. Velocities in gravel and other layers obtained are too few to be warranted as typical, and we hope to make similar and other measurements in the near future.
1966-10-31