A world first – Heavy Penetrometer automatically adapts to the soil hardness
The GRIZZLY is the first Dynamic Probing Super Heavy (DPSH) in the world to automatically adapt its impact energy to the hardness of the soils. This enables it to measure the dynamic resistance of the soils even more accurately.
Heavy dynamic penetrometers are the most suited for work on hard or very hard geological layers, where the soil resistance is over 50 MPa. However, for soft or very soft soils, the advantages of this type of equipment become its disadvantages: a single impact can sink the cone tip in by 10, 20, 30 centimetres or more.
In this case, the measurement made loses a lot of its finesse: for a depth of 1 metre, 30 measurement points are better than 3 to make an evaluation. However these soft zones are of great interest to geotechnical engineers.
To get around this problem, if it is possible with the equipment, the operator can lower the impact force (M) or the height from which M is dropped (H). The problem is that this requires several interventions during the tests to adapt it to the varying resistance of the ground. In other words, heavy and long operations (removal and refitting of protective cage, lifting the masses etc). In addition the soil resistance needs to be recalculated each time using the formula with M and H.
The technical solution developed by the R&D team of Sol Solution (Variable Energy GRIZZLY) still uses a fixed impact mass (M), but automatically varies H between four different values. This is all automatically commanded by the GRIZZLY integrated data acquisition system. Depending on the depth of penetration on the previous impact, using previously defined parameters, the onboard computer instantly decides on the value of H for the following test, so as to adapt in real time to the resistance of the soil encountered. During an evaluation, the more variations in resistance that are found in the soil, the more often the value of H changes. This requires no intervention by the operator or any interruption in the testing.
Furthermore, using the Dutch formula, the resistance of the soil is calculated automatically each time taking into account the value of H and thus the impact energy supplied. Again, no intervention is required by the operator. They simply need to select the impact mode at the start of the test: either the classic constant energy impact (DPSH-B), or the servo- controlled variable energy option. In this option, the 4 values of H available correspond to European standardised impact energies (EN ISO 22476-2). In extreme cases where the set of rods sink in themselves (no impact, just under their own weight), the penetration is still measured constantly in spite of this, and the following impact will update the total depth so that no information is lost.
This innovative technology is already installed on Sol Solution light dynamic cone penetrometers (PANDA®), and is now being adapted to the GRIZZLY® where its advantages can be seen when combined with the dynamic measurements at each impact to obtain other important rheological properties of the soil – load penetration graph, deformation modulus, wave velocity, viscosity… – and to measure the energy transmitted in the impacts.
I must confess that this equipment is fantastic compared to the old technology.
After scouring the market, we settled on the PANDA DCP test equipment as it offered the technical capability and, moreover, the flexibility required to work in the restricted environment our project presented; overhead clearance typically at 1500mm but as low as 1200mm. We had a unique problem that required a unique solution and that’s precisely what we found through the team at Insitutek and the PANDA equipment. The ease of assembly, intuitive operability and compact nature of the equipment, made light of the numerous soundings we required across a widely dispersed area.
The ZFG 3000 is an excellent tool and should be included in any professional contractors equipment list of assets. This tool should have a similar impact on the construction industry as the laser level. The ability to accurately and reliably measure this aspect of ground condition will improve the quality of the work and remove doubt as to the progress of the project.
I bought my ZFG 3000 and on the same day less than two hours later, it had paid for itself. Using this instrument, I was able to demonstrate scientifically, repeatably and independently the quality of the work that we had completed for our client. Ending the disagreement and creating an improved working relationship. Most jobs are not as confrontational as this was however, most jobs are built to a standard. The contractor can now measure as required, to know on site, at the time of testing if this standard is being achieved.
I strongly recommend the ZFG 3000 Deflectometer to any earthmoving, civil construction contractor. Good luck with your projects.
Insitutek Blogs
On 2 August 2024, geomechanics professionals gathered in Canberra for the Australian Geomechanics Society ACT Insitu Testing Practical Workshop. The event focused on practical demonstrations of key insitu testing methods, including Cone Penetration Testing (CPT), Static Plate Load Test (PLT), Dynamic Probing Super Heavy (DPSH), Light Weight […]
Have you ever wished your Plate Load Test equipment would operate itself? Then our static plate load test with automatically operating battery hydraulic pump is definitely something for you. 🙂 Typically, a hydraulic hand pump is used to apply 15 to 20 load increments over two loading cycles by the operator. One test lasts 20-30 […]
We want to share details of a practical AGS Insitu Testing workshop on 2 August, share something for those working on slope stability and for those in land development and tip you off on getting early bird prices for a couple of up-coming conferences in Australia. If you are interested in modern insitu testing methods […]