Steve,
We have some experience in using Dynamic Probes to drill holes to a maximum depth of 15 m in materials other than soft clays.
We have used dynamic probing to to assess the characteristics of colliery spoil, especially with regard to possible localitions of burnt areas and the differences in burnt and unburnt zones of the colliery spoil tip. The dyanamic probe handled the depth of the borehole relatively easily and would have probably been able to drill slightly deeper, however we ran out of rods and as the tip was still on fire they were getting too hot to handle. The system gave no indication of the geotechnical parameters, apart from a conversation to SPT N value, however the penetration profile was adequate to assess differences in levels of burning.
It is possible to install piezometers on completion of the probehole
If the system can drill through a variable material like colliery spoil then it should be able to drill through the conditions you are describing.
If possible it would be advisable to carry out some visual assessment of the materials using window sampling. This should provide enough sample to carry out basic analysis and a useful visual description, which is lacking in the dynamic probe method.
Regards
Simon Croxford
Engineering Geologist
IMC Consulting Engineers Ltd
PO Box 18
Mill Lane
Huthwaite
Sutton in Ashfield
Notts NG17 2NS
Tel : 01623 444611
Fax : 01623 440021
E Mail : [log in to unmask]
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