Abstract:

The vehicle operations on the entrance and exit transition road section of the straight or curved tunnel were simulated by dynamics simulation means. The dynamic responces of the vehicle before and after the road pavement change were obtained. The effects of the vehicle acceleration, the braking intensity, the pavement material transition location, and the adhesion coefficient change on the vehicle operation were analyzed. The simulation results showed that the abrupt change of the adhesion coefficient at the pavement material transition is the primary contributory factor to vehicle accident a tunnel entrance and exit due to the yaw of the vehicle driving through the parement transition from the uneven trie loads on the left and right sides. The effect of the braking behavior on the vehicle driving stability at the entrance and exit of a curved tunnel is more significant than that of a straight tunnel, and the acceleration behavior shows even a more obvious effect. The transition location has a large effect on the vehicle driving stability. The tunnel design showed extend the road asphalt pavement at the entrance section to the location where the braking of vehicle has ended , and locate the exit transition before the vehicle starts acceleration. The adhesion coefficient of the concrete pavement inside the tunnel should be above 0.35 to avoid excessive difference of the adhesion coefficient.

Key words: road engineering, tunnel pavement, tunnel entrance, pavement skid resistance, change of coefficient of friction, pavement materials