A Simple Analytical Method for Evaluation of Flexible Rockfall Barrier Part 1: Working Mechanism and Analytical Solution

Abstract

The flexible rockfall barrier system exhibits large deflection and complex contact behaviors such that sophisticated finite element method and full-scale test are widely used to design this kind of structures, which causes inconvenient for most engineers. In this paper, a simple analytical method is proposed for fast evaluation of the performance of the flexible rockfall barrier system on the basis of system deflection characteristics observed in the full-scale impact tests and, the component deflection characteristics from component tests such as the puncturing deflection of steel wire-ring net, elongation of energy dissipating device, sliding movement of supporting rope and rotation of support structure. The equation for prediction of large deflection of flexible rockfall barrier system was established. The overall deflection is contributed by its components and therefore the analytical solutions for calculation of component deflections were derived based on the space geometry analysis and verified by component tests. The analytical solution for steel wire-ring nets were validated by 17 puncturing tests and the maximum difference was less than 7.4%. Using the discrete ring net model, an explicit dynamic method was employed to simulate the nonlinear behaviors of flexible rockfall barriers with different design energies, i.e. 2000 kJ, 3500 kJ and 5000 kJ. The deflection of each component and the overall deflections from analytical solutions were compared with the numerical simulations with the maximum difference less than 7.9%. Thus, the proposed analysis solution for evaluation of large deflection of flexible rockfall barrier system is valid and ready for engineering design. A companion paper is presented in part two separately with full-scale test for further verification of the proposed method.

Optimization strategy for flexible barrier structures: investigation and back analysis of a rockfall disaster case in southwestern China

“…The back analysis of the rockfall impact on the flexible rockfall barrier was carried out using the FE method program ANSYS_2021_R1_LS-DYNA_mpp_r13 (LSTC, 2021). The simulation method is detailed in the literature (Yu et al, 2021(Yu et al, , 2018b. The model components were all constructed of nonlinear materials, and the component specifications of the computational model were similar to those of the project.…”

“…Whether the support rope enables sliding at the end of the steel column depends on the connection mechanism employed between the steel column end, the support rope, and the flexible net. The transition rope should be used in most cases where the design protective energy is 1000 kJ or less and the support rope does not slide a significant distance along the end of the column (Yu et al, 2018b). The transition rope can prevent the lateral force at the column end and the sharp rise in the axial force of the steel column generated by the net jamming, both of which cause the column to buckle (Fig.…”

An Analytical Method for Evaluating the Deflection and Load-Bearing and Energy Absorption Capacity of Rockfall Ring Nets Considering Multifactor Influence

“…However, the net is considered to act only as a structure distributing the force on the cables and the posts. Yu et al [26,27] obtained an empirical expression for calculating the punching deformation of the ring net. Guo et al [28] established a simplified model for the deformation and load-bearing capacity of the ring net, but it is only applicable to the square mesh, and cannot consider the influence of the boundary stiffness.…”