Permanent and Initial Ground Support for Tunnel Excavation

[sango]

Dear all,

By using estimated Q-values and empirical design chart proposed by Barton (1993), spacing of rock bolts, length of the bolts and thickness of shotcrete (unreinforced or reinforced) for ground supporting of a tunnel can be determined.

My questions are:

(1) How to determine size of the rock dowels, eg Y25, or Y32?

(2) The thickness of lining suggested by the chart can be interpreted as total thickness of permanent lining + initial lining?

(3) Any suggested design guilde for drill & blast rock tunnel?

Thanks a lot.

 

[jdonville]

sango,

Maybe have a go posting in the Underground Structure Engineering forum.

Jeff