Articles | Volume 12, issue 4
Nat. Hazards Earth Syst. Sci., 12, 1135–1149, 2012
Nat. Hazards Earth Syst. Sci., 12, 1135–1149, 2012

Research article 20 Apr 2012

Research article | 20 Apr 2012

Numerical and analytical investigation towards performance enhancement of a newly developed rockfall protective cable-net structure

S. Dhakal1,3, N. P. Bhandary2, R. Yatabe2, and N. Kinoshita2 S. Dhakal et al.
  • 1Graduate School of Science and Engineering, Ehime University, Matsuyama, Japan
  • 2Department of Civil and Environmental Engineering, Ehime University, Matsuyama, Japan
  • 3Nepal Engineering College, Pokhara University, Bhaktapur, Nepal

Abstract. In a previous companion paper, we presented a three-tier modelling of a particular type of rockfall protective cable-net structure (barrier), developed newly in Japan. Therein, we developed a three-dimensional, Finite Element based, nonlinear numerical model having been calibrated/back-calculated and verified with the element- and structure-level physical tests. Moreover, using a very simple, lumped-mass, single-degree-of-freedom, equivalently linear analytical model, a global-displacement-predictive correlation was devised by modifying the basic equation – obtained by combining the principles of conservation of linear momentum and energy – based on the back-analysis of the tests on the numerical model. In this paper, we use the developed models to explore the performance enhancement potential of the structure in terms of (a) the control of global displacement – possibly the major performance criterion for the proposed structure owing to a narrow space available in the targeted site, and (b) the increase in energy dissipation by the existing U-bolt-type Friction-brake Devices – which are identified to have performed weakly when integrated into the structure. A set of parametric investigations have revealed correlations to achieve the first objective in terms of the structure's mass, particularly by manipulating the wire-net's characteristics, and has additionally disclosed the effects of the impacting-block's parameters. Towards achieving the second objective, another set of parametric investigations have led to a proposal of a few innovative improvements in the constitutive behaviour (model) of the studied brake device (dissipator), in addition to an important recommendation of careful handling of the device based on the identified potential flaw.