MEASUREMENT OF VEHICLE PERFORMANCE TRAVELING ON ASPHALT-PAVED ROADS COVERED WITH VOLCANIC ASH

摘要

Japan has a lot of volcanic mountains and some of them have recently started increasing their volcanic activity. A large-scale eruption spreads volcanic ash over a broad area, which causes serious damage to social infrastructure. Even at times of disaster, vehicles have an important role in the rescue effort and transportation to help people. Accumulation of ash on paved roads has a significant influence on vehicle traveling performance and trafficability. This study examined the effects of volcanic ash on driving vehicles in terms of mechanics. Single wheel test equipment was used to measure the interaction such as friction coefficient and rolling resistance between a tire and volcanic ash on a paved road. The test equipment was 10 m long to measure forces exerted on the tire in the longitudinal direction under driving and rolling conditions. An asphalt mat of about 1 cm thick was glued on the metal hard test bed, and covered by volcanic ash with a controlled thickness. The test result showed that a very thin layer of ash was found to be very slippery, and the friction depends on the depth of the tire tread groove for a thickness of ash less than 10 mm. Over 10 mm thickness, the rolling resistance increased and the friction reduced with the thickness. Over 40 mm, the friction coefficient was nearly as low as that on a road covered with snow. A thickness over 100 mm made it difficult for vehicles to overcome the motion resistance. The set of tests on the indoor equipment was restricted to the wheel traveling at a very low velocity. An instrumented vehicle was introduced to measure the parameters with increased speed outside on an asphalt road covered with volcanic ash.