EXTRATING METHOD OF DEFORMED PART BY MICROTREMOR ON STONE WALLS OF JAPANESE TRADITIONAL CASTLE

Abstract

The non-destructive survey technique is required to estimate quantitatively the deterioration
level of a stone wall at a traditional castle site. Microtremor measurement method is one of the nondestructive survey technique to estimate geotechnical characteristics of the ground. In this study,
microtremors are measured at the stone wall of the Marugame castle, in order to evaluate vibration
characteristics of deformed or non-deformed stone wall; the method to extract the deformation part of the
stone wall is discussed based on the measurement results. The results showed that the value of H/V and H/H
spectral ration increased with the increase of deformation of wall but also by the elevation of a measurement
point. It was observed that the values of energy ratio were scattered widely. It is concluded that the H/H
spectral ratio is a suitable index to indicated the deformation level of a stone wall. By setting the adequate
threshold value, deformed walls were extracted roughly by the value of H/H spectral ratio at the Marugame
castle.