Abstract
Japan has a lot of volcanically active mountains. Recently, intense volcanic activities have been observed in a few volcanoes. A large-scale volcano eruption causes serious damage. Especially, volcanic ash is the most serious in volcanic hazards, because it has long term effects over large area. This affects economy, industry, traffic and the others seriously. Even in the hazard, vehicles need to run for rescue and transportation. In this case, we examined the effects of volcanic ash on vehicle running motion. We used an equipment to measure the interaction, such as friction coefficient and rolling resistance, between a tire and volcanic ash on paved road. We also examined the characteristics of multipass, the sinkage of tire and compared with silica sand. As a result, we confidently concluded that it is difficult for vehicles to run on ash-covered road. When ash falls less than 10 mm, vehicle run depends on a status of the tire tread wear. Over 10 mm, the friction coefficient and the rolling resistance increase with the depth of ash. Over 40 mm, the friction coefficient is nearly as low as one on the road covered with snow. In this case, driving vehicle has to be avoided. When ash falls more than 100 mm, a vehicle cannot run.
