For soil investigation, the bearing capacity (qu) is calculated from the dynamic cone resistance (qd) as follows:

Lateral friction is avoided with ‘lost’ cones of area 4 or 10 cm².The maximum resistance you can test with the PANDA® is about 30 MPa. Note that 1 Mpa = 1000 kpa = 10 bars = 0,1 KN/cm²

We want to use the PANDA® to test crane pad locations and we have calculated that the ground must withstand 100 Tonnes / Square Metre.

How does this relate to the PANDA® results?

100 t/m² = 100000 kg/m² = 1 MPa = 10 bars : that is the pressure the crane gives to the soil under the crane foundation (pads)(insulated foundations).

So the soil must be able to “retain” 1 MPa under the foundation. This must be the minimum bearing capacity qu of the soil under the crane foundation.

And with the following correlation qu (in bar) = qd (panda in MPa) x 10 / (12 to 15) – let’s take 15 for safety and use only the 4 cm² PANDA® lost cone in order to avoid the lateral friction around the rods.

In this case the minimum qd panda® tip resistance would be : qd (in MPa) = qu x 15 /10 = 1 MPa x 15/10 = 1.5 MPa

So you should need a qd PANDA® cone resistance (qd) minimum of 1.5 MPa for an enough depth of 2 times the width of the foundation (insulated foundations). For example, with a foundation of 1m x 1m, you should need 1.5 MPa with the PANDA® for 2 meters under the foundation.

Test Hole Spacing – at the university which makes the calibration of the PANDA®, they consider that you can make tests with the PANDA® with 15 cm between each test hole. 20 cm is a conservative value.