Rock Bolt Design

[Geocontractor]

Considering a project where there will be a 55' deep excavation. The top 13' is fill material (125 pcf) that can be laid back at a 1.5:1 slope. The lower 42' will be a vertical face cut by blasting the rock and excavating in lifts. The general shape of the excavation is square. Recovery on the rock is 85% to 100% and RQD ranges from 37% to 80%. Water table is about 7' below grade.

k=k(a)=0.33
k=k(o)=0.5

A crane will sit at the top of the excavation, so a 250 PSF surcharge should be assumed.

What is the best method to determine the spacing of rock bolts/anchors for this situation?

Thanks.

 

[exploengineer]

Totally depends on the structural geology and rock type. In may situations, bolting may not be required.

What type of rock is it and what type of structural geology?

Frank Lucca M.I.Exp.E.

http://www.terradinamica.com