INVESTIGATION AND SOIL PHYSICAL PROPERTIES OF DAMAGED POND EMBANKMENTS DURING TYPHOON NO. 19 AND THE HEAVY RAIN IN 2019

Abstract

 In this study, the specifications and rainfall conditions of the reservoirs in Miyagi, Fukushima, and Tochigi prefectures, which were collapsed by Typhoon No. 19 in 2019 and later heavy rains, were arranged. After that, the damage situation of the embankment of reservoir and the characteristics of the collapsed part were investigated by the field survey. In addition, the physical properties of the embankment materials were investigated by laboratory soil tests. As a result, it was clarified that the collapse of the reservoir occurred mostly around the structure of the embankment, and that many of the collapsed embankments of reservoir were constructed of sandy soil containing much sand. Furthermore, the factor of the collapse of the embankment of reservoir was estimated based on the field survey results. As a result, it was presumed that the shortage of the length of the impermeable sheet was the cause of the collapse in the surface impermeable type embankment. In addition, in the homogeneous type of embankment, it was presumed that the collapse history, the reduction of the cross section due to slip failure on the downstream surface, and the settlement of the embankment surface due to piping were the causes of the collapse.