dBasement
Geotechnical
- Mar 18, 2008
- 37
We are using a sonic rig to look at overburden in a very dense / hard fine-grained deposit that I believe to be weathered bedrock. The problem is, we are getting SPT results just below the casing that show blow counts of 30 or 40. In the meantime, the driller says its hard as nails and we are mushrooming casing. It makes me think that we are imparting way more damage to the deposit because of the vibration of the sonic rig than we think. I want to do a CPT (Cone Penetration Test) when we return to the site to confirm, but, is that a reasonable assessment?