GRIZZLY Options – Geotechnical Drilling, Standard Penetration Test (SPT) core sampler, torque wrench
The options for the GRIZZLY Dynamic Probing Super Heavy (DPSH) include:
- Geotechnical drilling head with Auger (diameter 63 mm) for geotechnical drilling and soil investigation at depth.
- Standard Penetration Test (SPT) core sampler (NF P94-116 standard).
- Window sampling and windowless sampling
- Torque wrench to control excessive lateral friction between soil and the rod.
Geotechnical Drilling Head
The geotechnical drilling head is a fully integrated attachment that allows the GRIZZLY to be turned immediately from a Dynamic Probing Super Heavy (DPSH) into a geotechnical drilling rig with a 63mm helical auger suitable for soil investigation. Depths of 10-15m or more can be achieved, depending on the soil type. Applications include helical auger drilling, soil sampling, geological profiling, pressumeter tests and the Standard Penetration Test (SPT).
Window sampling or windowless sampling is a technique used to bore through shallow soft soils to investigate the substrata in order to gain a profile of the ground conditions and to facilitate soil sampling for chemical and geotechnical analysis. Window sampling can be used for the investigation of contaminated land, for geotechnical investigations and for the installation of ground gas and ground water monitoring wells.
Standard Penetration Test (SPT) Core Sampler / Sampler Tube
The Standard Penetration Test (SPT) core sampler is an additional feature of the GRIZZLY Dynamic Probe Super Heavy (DPSH). To do the Standard Penetration Test, no correlation is required as the SPT uses the same standard energy as the DPSH- type B. The difference is that you have a 50 mm core sampling tool instead of a 20 cm² cone for the DPSH.
The Standard Penetration Test (SPT) is an in-situ dynamic penetration test designed to provide information on the geotechnical engineering properties of soil. The main purpose of the test is to provide an indication of the relative density of granular deposits, such as sands and gravels from which it is virtually impossible to obtain undisturbed samples.
To get the SPT values (no data acquisition on the GRIZZLY for this special application), the operator just has to note the number of blows each 150 mm or 300 mm. The sample tube is driven 150 mm into the ground and then the number of blows needed for the tube to penetrate each 150 mm up to a depth of 450 mm is recorded. The sum of the number of blows required for the second and third 150mm’s of penetration is termed the “standard penetration resistance” or the “N-value”. In cases where 50 blows are insufficient to advance it through a 150 mm interval the penetration after 50 blows is recorded. The blow count provides an indication of the density of the ground. The Standard Penetration Test (SPT) procedure is described in the French Standard NF P94-116, British Standard BS EN ISO 22476-3, ASTM D1586 and Australian Standards AS 12126.96.36.199.
The torque wrench is used to measure the lateral friction between the material being tested and the rod stem to identify whether the torque (Nm) is within the acceptable limits, defined by the standards NF XP P94-063 for control compaction and NF P94-115 for soil investigation.
The torque, measured before each additional 1 m rod is added, can be entered into the GRIZZLY software and printing on the penetrograms.