Rock Sheds and Rock Impact Forces 1

[jmen]

I am currently in the preliminary design stage for a rock shed/shelter. It is for a road that has had some large boulders come down onto it in the past.

The protection/energy absorption system that sits on the r/c roof we are currently planning on using is a 1m (3.3 ft) layer of polystyrene, with a 1.5m (5 ft) rock (6-8 inch nominal dia.) layer above.

The energy of the rock impact is currently being modelled, and this is in MJ. To get the impact force (P), an estimate of the stopping distance (delta) needs to be made. Ie P = Energy / Delta

I would appreciate if anyone could perhaps give some comments, or suggest references/web sites for:
a. The protection/energy absorption system
b. The stopping distance. Currently using 2ft, but I suspect this is conservative!

 

[GeoPaveTraffic]

I don't have any direct information; however, you might want to check with the Colorado Department of Transportation. They have several rock fall modeling programs.

 

[IRstuff]

Kind of interesting Powerpoint presentation:

http://www.mirarco.org/profdev/courses/slope/docs/ee02-lecture-3x.pdf

mentions a simulation program called Rocfall

TTFN

 

[IRstuff]

Another interesting link:

http://www.ptc.psu.edu/papers_p.shtml

TTFN

 

[MHansen]

This message is being sent to share my experience with designing a rockfall shed for a 10' 80,000# rock falling from 350'= 115 mph impact. Have considerable information to share including from Dr. Hiroshi Yoshida-Japan, Sandia Nat. Laboratories, and others on computing impact effects [ie via CRSP, Abacus-Explicit, cratering and penetration] and mitigating for same, ie with geofoam + sand cushion + etc....

Space prevents describing the above in detail but feel free to ask specific questions.

MP Hansen, PE

 

[MHansen]

Rockfall tests conducted in Europe and Japan have developed energy equations consistent with the Hertz Contact Theory. A confirming independent approach was developed using Conservation of Momentum, to estimate forces with accidental impact on buried utilities, during Dynamic Compaction on soil [dropping of weights from a crane].