The imperative need to protect structures in mountainous areas against rockfall has led to the development of various protection methods. This study introduces a new type of rockfall protection fence made of posts, wire ropes, wire netting and energy absorbers. The performance of this rock fence was verified in both experiments and dynamic finite element analysis. In collision tests, a reinforcedconcrete block rolled down a natural slope and struck the rock fence at the end of the slope. A specialized system of measuring instruments was employed to accurately measure the acceleration of the block without cable connection. In particular, the performance of two energy absorbers, which contribute also to preventing wire ropes from breaking, was investigated to determine the best energy absorber. In numerical simulation, a commercial finite element code having explicit dynamic capabilities was employed to create models of the two full-scale tests. To facilitate simulation, certain simplifying assumptions for mechanical data of each individual component of the rock fence and geometrical data of the model were adopted. Good agreement between numerical simulation and experimental data validated the numerical simulation. Furthermore, the results of numerical simulation helped highlight limitations of the testing method. The results of numerical simulation thus provide a deeper understanding of the structural behavior of individual components of the rock fence during rockfall impact. More importantly, numerical simulations can be used not only as supplements to or substitutes for full-scale tests but also in parametric study and design.
There are various protection measures against rockfalls. An embankment is effective in rockfall hazard mitigation at a dangerous slope end. The slope rockfall tests on full-scale embankments have been carried out. These embankments are made of sandy soil reinforced with geogrids. The cushioning layers which are made of geocells filled with crushed stones of 5-13 mm in diameter are also placed on the mountain side of the embankment. A boulder, i.e., RC block rolls down the test-site slope, and hits against the embankment. A new system of measuring instruments is employed in order to evaluate the impact force and the impact energy. One of important observations is a possibility that a rolling boulder carries it toward the top of an embankment because of its rolling momentum. The experimental results, especially the relationship between impact force and impact energy is discussed in this paper.
<p>The construction of systems to prevent falling rocks implemented in Japan commonly uses rockfall protection nets. We assumed that equipping rockfall protection nets with newly-developed energy absorbers would improve the ability of the nets to absorb energy. This research involved conducting tests to confirm the performance of the energy absorbers, as well as full-scale tests of the rockfall protection nets, and evaluating rockfall protection nets equipped with energy absorbers. The results demonstrated that rockfall protection nets equipped with energy absorbers are able to absorb an increased amount of energy, and reduce the force acting on the wire cables and anchors connected to the energy absorbers. In other words, installing energy absorbers on rockfall protection nets provides several advantages.</p>
This study uses a numerical procedure, previously validated with data from full-scale experiments, to investigate the performance of a modified prototype wire-rope fence to provide protection against rockfall. The cost-reducing modifications are increased post spacing and fewer wire netting layers.The numerical procedure provides the nonlinear response of the prototype under various impact conditions and insights into each component's role in dissipating impact energy. A simple but effective method to increase fence capacity is also developed. Finally, the use of two units of the prototype to protect a wide area is investigated employing the numerical procedure.
Shock absorbers are often situated on top of rock-sheds to mitigate the effects of geological disasters such as rockfalls. In this study, three full-scale impact load tests, with impact energies of approximately 250, 500, and 1000 kJ, investigated a new type of shock absorber comprising expanded polystyrene, steel material, and sand cushion. Comparing the results of the full-scale tests with the results through sand cushion-a common material used for shock absorbers-the maximum impact load in this study was reduced by around 50% than the empirical formula suggested by a rockfall mitigation code. Besides, the study utilized LS-DYNA finite element software to find out the limitation of energy absorption, accuracy of simulation, input parameters for inferential impact formulas of the shock absorber, and to generate a reasonable simulation for use in further research and design of rock-sheds.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.