Plate bearing test

[Brendeb1]

Hi there are hopefully someone can help with some plate bearing test information

I currently work for a ground worker to carry out qa checks on formation / piling mats etc using a plateman system plate bearing equipment .

Getting results for cbrs is a doddle , where I come unstuck is where we have to prove a crane or piling mat.

The client will always give a maximum kn/m2 required for the rig or crane.
The plateman system gives k value in Mn/m3 and k762 in Mn/m3

How do I convert from the k modulus to the maximum bearing pressure.

Also , how do you convert from mpa to kn or tonnes?

Any help would be much appreciated

 

[newa]

Brendeb1,

As you require maximum bearing pressure for carne pad (which is short term load), I am comfortable with Plate Load testing. However, if you want allowable/Ultimate bearing pressure for permanent structure (especially in Clayey Soil) full geotechnical investigation and testing is necessary.

Determining allowable bearing pressure with plate load test is fairly easy as long as the crane is far from any slope or not adjacent to the bank of the river. in such a case slope stability is what you should be more concerned of.
I would not do plate load test if it is just the crane pad verification as 20mm settlement or 50mm settlement does not matter to the crane as long as there will not be any shear failure. I would simply look at the geotechnical report for that site and carry out DCP test to figure out if the ground confirms to the report and give the client estimated allowable bearing pressure. If geotech report is not available carry out DCP and use empirical relationship to get allowable bearing pressure.

If the client insist they want Plate Load test then choose limiting settlement for e.g 25mm. Carry out plate load test and read applied pressure to induce 25mm settlement. The pressure you get is Ultimate Bearing Pressure. Divide the number with appropriate factor of safety to get allowable bearing pressure of the soil for 25mm limiting settlement.

Bear in mind that for permanent structure in clay, settlement analysis shall be carried out to determine the allowable bearing pressure. Plate load test has limitation as it cannot simulate the size of the footing and influence depth.

Please comment if anyone disagree. I am open to discuss and learn myself.