DISPLACEMENT BEHAVIOR OF TREE INTRUDED-FRACTURES AT A ROCK SLOPE

It can often be seen that trees and roots intrude fractures at rock slopes. Under these situations, it is expected that the rock slope can gradually become unstable with the growth of the trees and roots, and eventually, rockfall may occur. In this study, fracture displacements were measured in-situ for three and a half years at a rock slope in Hakodate, Japan, facing the Pacific Ocean. As a result, an apparent long-term fracture opening was observed during the tree growth period from spring to summer. There are also small disturbances in the displacement with shorter periods. Comparison with weather data suggests that the fractures tended to open slightly due to rainfall and when the wind blew from the ocean. A slight opening caused by an M5.3 earthquake was also observed.