quartzite rock cut

[gavrock]

we are designing our house and a road that will have signifigant cuts (25')in the quartzite with proposed cuts up to 0.25:1 (h:v). We were given the option of a flatter slope, which would likely decrease the likelihood of rockfall but increase our costs very quickly. Are there "rules of thumb" associated with rock cuts, stability, and costs?

 

[Focht3]

Yep. You need a local geotechnical consultant to help you with this. There is too much to consider to give you an answer here. Hopefully some others will chime in with some things to be considered...

 

[exploengineer]

There are other options for slope control. You can easily put in a catch bench at 12'. This is accomplished easily. Also, the blasting contractor can angle drill the blast holes up to 25 degrees. I recommend that 15 - 20 degrees maximum be used becuase it is easier to drill them.

This will give a nice slope to your final wall. Using this in conjunction with a catch bench (about 3-4 feet wide) on the final wall will help to mitigate problems of stability on your final wall and reduce rock falls.

You can also using other wall control techniques such as presplitting the wall. This can be done very nicely in most quartize. This leaves the appearance of the half circles on the wall like you see on road cuts. This can also be done with angle drilling and a catch bench to really help. All of these are much cheaper and easier then using a big slope.



Frank Lucca

http://www.terradinamica.com