Damage to earth dams

Abstract

As a result of the 1995 Hyogoken-Nambu earthquake, about 1,200 relatively small-scale earth dams used for irrigation suffered some sort of damage. Since there was such an enormous number of damaged areas, survey data have not yet been sufficiently compiled. Using the results of damage and soil surveys obtained so far, this paper describes and characterizes the damage sustained by earth dams. Damage was seen in earth dams within a radius of 90 km from the epicenter, with most of it occurring within a radius of 30 km. Compared with previous earthquakes, major damage was of a greater extent from this 1995 occurrence. Damage in some of the earth dams subjected to soil surveys may have been caused by liquefaction. In fact, there is a strong possibility that liquefaction may have been responsible for large-scale damage such as 'rupturing'. Finally, data from this and previous earthquakes proved that a constant relationship exists between the anticipated maximum damage rate of earth dams and magnitude, which is a function of the average distance of a region from the earthquake's epicenter.