常時微動の測定結果より求めた地盤内のひずみ分布

Abstract

The investigation of strain is presented by means of the observation of microtremors in the sub-surface layer and theorecical calculation by S-wave Multi-Reflection Method together with Lumped Mass Method for Love and Rayleigh waves. The results of the investigation are summarized as follows : (1) The strain value varies rapidly at the depth of 10m below the surface of the ground, where the S-wave velocity decreases rapidly with comparison of the upper region above the depth of 10m. (2) The shear strain, especially, due to the horizontal component of Love and Rayleigh waves becomes large at the 10m depth, and the tension strain due to vertical component of Rayleigh wave gradually takes a comparatively large value from the depth of 10m to the ground surface. (3) In comparison with the observed and calculated values for strain distribution in depth direction, the observed strain of two horizontal components corresponds to the theoretical results of Love and Rayleigh waves. The observed strain of vertical component, however, is not so good corresponding to the value calculated from Rayleigh wave.