Risks of the Spontaneous Ignition of the Rubble which Caused by the Heat Generation of Fermentation

Abstract

The Great East Japan Earthquake has resulted in the generation of a large amount of rubble, and subsequently, many ‘outdoor rubble storage areas’ have been established in the disaster areas. However, since summer of 2011, about 30 fires occurred in the Tohoku district’s outdoor rubble storage areas. One of the causes of these fires is believed to be the proliferation of microorganisms and fermentation of the organic material present in the rubble piles. The heat generated during fermentation ultimately results in spontaneous ignition. The authors of this study conducted field surveys of two rubble storage areas in Yuriage and Kozukahara, Natori City, Miyagi Prefecture where fires have occurred. Rubble samples containing material conducive to fermentation were collected from the fire-affected areas and the risk of spontaneous ignition triggered by the heat generated during fermentation was examined. The results revealed that the heat generated during fermentation of rotten tatami mats and wood chips is most likely to act as a trigger and become a cause of the fire if adiabatic conditions are good. Abstract