How to determine the friction angle

[wshi]

Hello all:
I am involed a site invesigation project in which I will have to determine the bearing capacity and friction angle of the soil.
The tests we have performed included seive analysis,atterberg limits tests and SPT. These soils are silty sand or silty gravels. According to these three tests, how to decide the friction angle and bearing capacity? Is there any emprical formulas available?

Any recomendations are appreciated.
Thanx

 

[jdonville]

xixia,

To determine the friction angle experimentally, you could perform a direct shear test.

USACE EM 1110-2-2504 Page 3-3 has a chart (after Teng) showing empirical relations (based on laboratory results) between dry density, USCS classification, relative density and friction angle.

Caveat emptor.

From there it should be a simple matter to estimate the bearing capacity of this soil for your application.

Jeff


Jeffrey T. Donville, PE
TTL Associates, Inc.

http://www.ttlassoc.com

 

[wshi]

jdonville:
That chart seems helpful, thanks