Analytical study on impact response characteristic of wire ring net system by using the concept of particle method

In Japan, there are a numerous steep mountainous areas and severe seasonal heavy rainfall is common. Thus, rock-fall accidents occur in mountain regions annually. In order to protect an arterial road, the urban areas and human life from rock-fall accidents, various protective structures had been constructed. Previously, most of them have been made of reinforced concrete such as the Rock Sheds. However, they require huge construction costs and impair the surrounding landscape. Hence, new economical protective structures have been considered for a long time. From these needs, several high-energy absorption rock-fall nets have been developed. Some of them have specialized shock absorbing devices or specialized columns with plastic rotation capacity. Wire frame structures (called the wire ring net system) are composed of several interconnected wire rings of about 30 cm in diameter and are predominantly used 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 highly-effective structures. The wire ring net system is composed of many parts (wire ring, wire rope, supporting post, brake system, etc), and 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 has been only confirmed by full-scale falling weight tests. Although, there are several cases that evaluate the performance by similar testing in Japan, the test condition is limited by restriction of test station and costs. Therefore, this study aims at simulating the impact response of wire ring net system by using the concept of particle method.