Impact Response Analysis of Wire Ring Net System Using the Concept of Particle Method

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In Japan, there are many steep mountainous areas and we have local severe rain in the season, thus rock-fall accidents occur in mountain regions year after year. In order to protect an arterial road and the urban areas from the rock-fall accidents, various protective structures had been already constructed. However most of them are made of reinforced concrete and they require huge construction cost. Hence a new economical protective structure has been expected for a long time. From these needs, several high-energy absorption rock-fall nets have been developed. Some of them have specialized shock absorbing device or specialized column which has plastic rotation capacity. On the one hand, wire frame structure (called the wire ring net system) that is composed of interconnected many wire rings of about 30 cm in diameter are predominant in Europe. Because these structures can absorb large kinetic energy of a falling rock due to their deformation capacity, they are introduced from Europe as the highly-effective structures. The wire ring net system is composed of many parts (wire ring, wire rope, supporting post, etc), and it does not require large bases due to its light weight. However, there is no analysis method that can calculate their impact response (dynamic behaviour and energy absorbing capacity), and it has been only confirmed by the full-scale falling weight tests. Although, there are several cases that evaluate the performance by same tests in Japan, the test condition is limited by restriction of test station and its cost. Therefore, this study aims at simulating the impact response of wire ring net system by using the concept of particle method. The following conclusions are obtained from this study. 1) The proposed method can simulate the impact response of the wire ring net system. 2) Fracture of the wire ring net is predicted applying critical strain limit for the material.