Daijyu HORIGUCHI
Analysis of earthquake damage at Takamachi housing complex using geographic information and study on damage estimation method of land developed for housing lots.
satoru OHTSUKA
In recent years, the basis of design for residential land development was revised by the occasion of the Great Hanshin Earthquake.In investigation for earthquake-proof safety of land development, it is convenient to select dangerous parts in the wide area prior to investigation.This study analyzed the factors of damaged buildings in the Mid-Niigata Prefecture Earthquake in 2004 and examined the model to estimate the damage degree by GIS.
The rate of building collapse in Nagaoka and Ojiya cities was investigated by multiple regression analysis with predominant period, H/V mean multiple factor, elevation of ground and macroscopic incline angle.Although the reliability of result was low, the coefficient of determination was obtained comparatively high, and the correlation among factors was found to be high.
In examination of the damage at Takamachi housing complex, the distribution of cut and fill was estimated with GIS by comparing geographical maps before and after the residential land development.It was examined by performing surface wave inquiry to analyze the s-wave velocity of ground. The result expressed the good coincidence in estimation of land fill distribution except the specific part of land development. It may be due to the accuracy of geographical map and it is left to the further study.Through the analysis on ground deformation and damaged buildings, about 70% of ground surface cracks and 100% of slope failures were found to locate in the filling part. Moreover, damaged buildings were found to concentrate the fill and the surrounding area.
Although the damage of building was relatively concentrated on fill part, it is noted that the serious damage can be seen in cut area close to fill.The same result with the building damage was obtained for ground surface cracks.High correlation between building damage and ground surface crack can be easily seen.From the stochastic analysis, the rate of building damage in fill part was found double for that in the whole area. It became about triple in case of houses on ground surface cracks.It is effective to estimate the damage of buildings by not only the fill and cut area distribution, but also the prediction on ground surface cracks.For the purpose to predict the crack generation position, it was investigated for the fills of convex , straight line and concave types.Stochastic analysis was conducted on the relationship between the fill shape and ground surface crack position, however the discussion was left to the further study.
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