LEI Fan,PENG Wu,HU Yang,et al.Design Method of Passive Safety Net System Considering the Angular Velocity Effect of Rolling Boulders[J].Journal of Disaster Prevention and Mitigation Engineering,2024,44(05):1030-1040.
LEI Fan,PENG Wu,HU Yang,et al.Design Method of Passive Safety Net System Considering the Angular Velocity Effect of Rolling Boulders[J].Journal of Disaster Prevention and Mitigation Engineering,2024,44(05):1030-1040. DOI: 10.13409/j.cnki.jdpme.20230901005.
Design Method of Passive Safety Net System Considering the Angular Velocity Effect of Rolling Boulders
To reveal the influence of angular kinetic energy of rolling boulders on the mechanical response of passive safety net systems and to improve existing design and testing methods
a nonlinear dynamic numerical model of passive safefy net system was established using LS-DYNA. The effectiveness of the numerical model parameters was verified through comparison with full-scale impact tests. On this basis
the influence of the proportional coefficient of angular kinetic energy (λ) on the system deformation and internal force was analyzed. A fitting relationship between the peak internal forces of various components and λ was proposed
and a design amplification coefficient (ζ) for the internal force considering the rotational effect was provided. The results showed that after applying rotational kinetic energy
the maximum vertical displacement of the boulders decreased as the λ value increased
and the boulders exhibited a clear outward rolling motion in the horizontal direction
with a significant increase in deformation of the upper support rope. The impact force of the boulders and the peak internal force of the components followed a quadratic polynomial relationship with λ. The internal force of the netting
steel column
upper support rope
and anchor rope initially increased and then decreased
reaching their maximum when λ=0.2. As λ increased
the energy absorption of both netting and dissipators decreased linearly
while the energy dissipated by sliding and friction increased linearly. Therefore
the angular velocity effect of rolling boulders increased the impact response of the main components in the passive safety net system
and this adverse effect should be fully considered in design. It was suggested to apply the internal force amplification coefficients specified in existing standards to provide safety reserves for the components
while also adding a design internal force amplification coefficient for the steel posts
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