Felled Trees as a Rockfall Protection System, Experimental Study for Numerical Models Calibration

Abstract

In mountain areas, natural hazards, such as snow avalanches, landslides and rockfall threat towns, communication routes and people. It is known that forests have a major capacity to dissipate rockfall energy. Forest maintenance or storms can reduce forest’s protective capacity; after such a reduction, felled trees can be strategically left on the slopes in order to replace live trees. The efficacy of these devices and their optimal position can be analyzed by developing a numerical model describing the rock-wooden device interaction. To develop a relevant model of these wooden devices when impacted, the research was focused, in one hand, on a rigorous characterization of the fresh wood mechanical properties to recreate the real dynamic response of stems after the impact. In the other hand, the local impactor-wood stem interaction at the contact point was analyzed. Laboratory experiments using Charpy pendulum, presented in this text, have been carried out to assess the calibration of the numerical model. Experimental results of the impact force and their relation with stems mass and the impact energy level were treated and commented. A second serie of experiments has enabled to characterize the law describing the contact between the stem and the impactor.