piles 1

[jondeere]

Hi, question from a C/P driller, so appologies if it is worded wrong!.
Trying to resolve an argument with engineer about depth of bore hole drilled with Pilcon rig. At 35mtrs the weight of the casing alone (150mm) is close to the maximum single line pull of the rig. I know its hard to say without looking at samples/logs, if the casing weighs 1500kgs, due to the skin friction on the casing, appprox how much extra in Kgs has the rig got to lift to pull casing out?
The strata is mixture of loose/soft wet sand/silt.
Regards,weight
JD

 

[civilperson]

Not only adhesion of soil to wall of cassion but also inertia to accelerate the stationary steel to a upwards velocity. The impact factor for overcoming inertia is 15-20% of weight and the soil adhesion can be as high as 70 KN/m<2,(1,460 lb/ft<2) for depths greater than 15 diameters. This assumes a phi of 35 degrees for the sand and a soil friction angle of 21 degrees with time for the sand to lose excess water pressure, (use a sixth of earlier value for immediate retreval with the winch). Thus total pull is over 190 Kn.