Pocket Penetrometer

[ruleofthumb]

I've got a question about the usage of the pocket penetrometer(PP). Its come to my understanding that some geotechs do not use the PP when it comes to cohesive soil. They rely solely on the N values to determine the strength of cohesive material. Initially, I thought this was an industry standard. I bring this up due to the fact that the N values and the PP values could be quite different and thus the recommendations the geotechs provide vary significantly as they depend on these values.

 

[GeoPaveTraffic]

Both methods have their limitations and some engineers prefer one over the other. A lot depends on local practice.

My preference is to use laboratory and vane shear tests. But in the end, I consider all data and make my best estimation of the soils. Then these estimations are confirmed during construction (the observational method).

Mike Lambert

 

[GeoEnvGuy]

Where I work the cohesive soils have N=0, 90% of the time. So in my area the N value is useless. PP gives you some reading, more interested in vanes and lab tests for cohesive soils.

 

[geotechguy1]

When I worked in Alberta we usually used the pocket pen to gauge how consistent the shear strength was along the soil profile, and relied primarily on SPTs for the actual values.

 

[MotorCity]

I always thought pocket penetrometers were used to provide a rough estimate of soils strength on site, whereas other lab tests were used to come up with more accurate values of soil strength that are provided in Geotech reports.