Dynamic Penetrometer (DPH) conversion

[civilmg]

We have performed some work out of country where conventional SPT was not employed. Rather, dynamic penetrometer soundings were performed. Specifically, the method employed is referred to as "DPH". Could someone provide me with information that will convert the DPH data to standard blow counts?

 

[BigH]

civilmg: Sit back and look at your post. Most of us (including I who have worked overseas for some 14 years) have not heard the term DPH. We need some details. Is it a cone that was driven into the ground using a hammer (like the Canadian pentest (2 inch 60 deg apex cone driven with 140 lb. hammer dropped 30 inches) or is it the Sower's dynamic cone (see some other posts for definition) or is it a TRRL miniature dynamic cone (small 0.5 inch tip driven with light hammer). Or is it something different from a "cone" - such as driving a tube (perhaps closed ended) into the ground . . . or . . . Once we have a handle on the details, you might get some assistance - unless you do find an engineer out there who has heard of it specifically.

 

[civilmg]

DPH (dynamic penetrometer-heavy) specs

weight of striking mass: 50kg
freefall height: 0.5m
weight of striking system: 18kg
diameter of cone tip: 43.7mm
area of tip base: 15 cm^2
rod length: 1m
weight of rods: 6kg/m
depth of first rod to joint: 0.8m
tip penetration: 0.2m
cone tip angle: 90degrees

this is the information that was provided to me. let me know if this is not the data that you need. thanks for your help.

 

[BigH]

Good details - and thanks: Its a bit different animal than the Canadian used pentest that I described but the mass is almost the same (a bit less being 50 rather than 65 kg) and the freefall is only 18 inches approximately. What gets me is the 90 deg cone tip - that's pretty blunt. What country? I've personally not run into a cone like this. For the Canuck pentest - to get an idea as this is a heavy test too - see the Canadian Foundation Engineering Manual.

 

[civilmg]

The client prohibits us divulging the exact location but that the site is in Eastern Europe and the equipment seems to be a relatively common beast in Northern Europe Germany. We are using Italian GeoStru geotechnical software to analyze this and are trying to make sense of the computations and results before publishing anything formal.

 

[soiledup]

Ohhhh,, You are dynamic probing!!

This is a basic technique we use sometimes in the UK depending on site conditions. From the details above I can see that you are using the DPH setup (Dynamic probing Heavy. See BS 1377:1990 Soils for Civil Engineering - In-situ testing (Page 23!!)

The results should be presented to you as : the number of blows per 100mm (N100). This method is slightly different from the traditional SPT used on cable tool rigs, but many generalised comparisons can be drawn.

The comparitive N value can be derived: N = 2 x N100. Basically the sum of any two increments on the rods.

WARNING that this is very generalised. I'd use the comparision as guidelines only - I would not use these for design purposes.

 

[BigH]

Soiledup - many thanks for your input. My library of BS is limited. Knew someone in the group would know it!

 

[civilmg]

thanks...you guys are a great help

 

[eric1037]

BigH:

My library of BS is pretty large. Unfortunately, I doesn't contain anything on British Standards.

 

[civilmg]

soildeup-
Is there a URL to get a copy of that standard (assuming it isn't too large)?

thanks

 

[BigH]

eric1037: . Similar to many university degrees, too!

 

[soiledup]

civilmg,

There is a website called 'tionestop.com' (ti = technical indexes)whereby the documents can be accessed. You'd need to log in. But that is the best that I can do.

regards

soiledup