斜面安定に対する竹林地下部の力学的効果

抄録

Recently in Japan, bamboo species have been expanding into neighboring forests. This is cause for concern because such changes in vegetation can lead to destabilization of steep slopes. However, the relationship between the expansion of bamboo forests and the change in slope stability has not been fully clarified. Therefore in this study, we attempted to develop a new method to evaluate the effect of bamboo rhizomes on slope stability. This paper reports the characteristics and suitability of this method. First, we surveyed a slope, that had failed due to heavy rainfall in August 2014 and had been dominated by the Moso bamboo (Phyllostachys pubescens). Bamboo rhizomes were distributed in a shallow layer on the ground ; their underground stems were cut when the slope failed along its edge. Considering these characteristics of bamboo rhizomes, we developed a new model for the analysis of slope stability. Subsequently, we investigated the spatial distribution and ultimate tensile strength of bamboo rhizomes on steep slopes. To confirm the validity of the developed model, the stability of the failed slope was analyzed, taking the results of field investigations into consideration. Based on the results of the analysis, an appropriate safety factor was obtained and it can be concluded that our model was valid for evaluating the effects of bamboo rhizomes on slope stability.