3. A New Type of Protection Fence for Small-Scale Rockfalls

      Rockfalls along railway lines have in most cases the kinetic energy of 100 kJ ( 10 tm) or less, and a protection fence for falling stone using diamond-shaped wire gauze is generally used as a countermeasure. However, in some places such a fence cannot be built due to construction restrictions and thus a more effective fence has been demanded.
      A new type of wire gauze (extensible net in Fig. 1) was devised and used in the development of a new type of simply-structured protection fence for falling stones. The extensible net is wire gauze, built by netting coil-shaped element wire, and can absorb more energy than diamond-shaped wire gauze due to the larger deformations of its more three-dimensional structure. In addition, the new-type fence has the benefit of low cost due to its simple materials.
      To check the performance of the new-type protection fence, full-scale tests were performed under various conditions (Fig. 2). The tests demonstrated that the fence can adequately cope with the kinetic energy of rockfalls of approximately 70 kJ, and can capture rockfalls of up to 100 kJ with some damage to posts. Furthermore, support structures depending on ground conditions were examined with the assumption that the new-type protection fence will be built halfway up a slope (Fig. 3).
      This study was conducted with a government subsidy from the Ministry of Land, Infrastructure and Transport.

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