Experimental Study on Impact Absorption Capacity of Various Expanded Materials for Rock Shed

Abstract

In recent years, there has been a continuous increase in the intensity of natural disasters. Slope disasters such as rock falls occur along coastlines and in mountainous regions. Rock shed structures are implemented as measures to prevent rock fall damage; however, these structures deteriorate over time, and their impact resistance also decreases. As a supplementary measure, a method employing foam material as a cushioning material has been used in practical applications. However, the effect of the compressive strength characteristics on the cushioning performance of foamed materials has not been studied thus far. Therefore, in this study, falling-weight impact-loading tests involving various fall heights were performed to examine the absorption performance of various expanded materials. Moreover, we examined the case where core slabs were layered to effectively exploit the absorption performance of the expanded materials. The results of this study are summarized as follows: (1) the transmitted impact penetration stress-strain curves right under the loading points of various expanded materials exhibit properties similar to those obtained from the results of material testing. However, in the case of expanded materials with high compressive strengths, the compressive stress from the results of material testing tends to be lower. (2) In the case of expanded materials with high compressive strengths, with and without core slabs, the distribution of the transmitted impact stress is large, and the energy absorption capacity is high. (3) In this experiment, the energy absorption capacity was found to double when core slabs are layered, regardless of the type of expanded material used. This suggests that expanded materials with high compressive strengths may contribute towards a higher improvement in energy absorption capacities, by using layered core slabs.