ABSTRACT
A great number of stone guard fences that protect the traffic of mountainous roads from rockfall impacts have been constructed so far in Japan.
Most of the existing fences, however, has not satisfied the performance requirements with respect to absorbing energy of rockfall impacts because the fence was originally designed by a target design rockfall impact. There are many cases that a new larger stone than the initial design target stone scale was often found during the periodic site investigation. This means that a lot of mountainous roads are in peril of rockfall impacts. Therefore a quick execution of the treatment to upgrade the performance of existing stone guard fences is required. At the same time, expensive cost is estimated if the insufficient fences are replaced to new ones. Accordingly, development of a reasonable upgrading technique for the existing fences has been required.
