Soil Nailing to CIRIA 637

[martyno1]

Hi,

I'm currently undertaking preliminary soil nail design and I am using both HA 68/94 and CIRIA 637. Unfortunately CIRIA 637 does not explain very well the use of "gamma p" [sorry can't insert symbols!]. Equations 8.3 and 8.4 show that by using "gamma p" we are factoring UP the pull out resistance when normally we would factor the resistance DOWN? Is this a mistake in the CIRIA guide and should equations 8.3 and 8.4 read 1/"gamma p"?

Additionally the CIRIA guide jumps between characteristic and design soil parameters suggesting these have been factored down (I assume using EC7 DA1-C2). Surely we would not factor soil parameters DOWN yet multiply them UP using this "gamma p" value? Is this another mistake within the CIRIA guide and should equations 8.3 and 8.4 use characteristic rather than design soil parameters?

Has anyone else had a similar experience and if so what would they recommend? Should I stick with HA 68/94 which is much more clear?

Thanks in advance,

Martin

 

[Lovi]

Martin,

If you're using 8.3 and 8.4 to calculate the bond length of then nail, then you want to factor the pullout strengh up. This will result in longer, safer nails.

Also, use design parameters!

Lovi