Abstract
The estimation method of damage caused by liquefaction due to earthquake is proposed by making use of the great earthquake damage data in the Tokai district, central Japan, where the disasterous earthquakes had been repeatedly occurred in the past. In Nagoya city, western part of Tokai district, damage of wooden houses due to liquefaction is brought in case of the past three destructive earthquakes which are the 1891 Nobi, the 1944 Tonankai and the 1945 Mikawa Earthquake during preiod from 1800 to 1950. The empirical equation of damage estimation is formulated from several factors, such as activity of ground liquefaction, irregularity of ground structure, duration time of seismic waves and strength of houses, which are applied to the sites of ground liquefaction based on literature review. The results are summarized as follows : (1) The severe damage to houses due to earthquake is explained by taking account of the effect of ground liquefaction occurred during earthquakes. Damage due to liquefaction is more than 20 to 40 per cent larger than that caused by the strong ground motion without liquefaction. (2) The correlation coefficient of the damage ratio of past earthquakes in relation to that of calculated value by the empirical equation is 0.929. This equation is [numerical formula] where Y is the damage ratio in percent, S_1 to S_3 are correction for the duration time of seismic waves (see Table 3), G_1 to G_3 are correction for the irregularity of ground structure (see Figure 14). B_1 and B_2 are correction for the individual foundation strength of wooden houses and the strip footing foundation one, respectively. P_1 is the numerical value of liquefaction potential calculated from the comparison of shear strength of sandy soil layers and the maximum acceleration on the ground surface. (3) The estimation of damage ratio for the future great earthquake, occurrence of which is expected in this Tokai district, are more than 15 percents in the area near sea and river basin in Nagoya city. The damage ratio due to liquefaction is more than 3.6 times that caused by the strong ground motion.
