Back to results
US 4,614,110 AGranted
Device for testing the load-bearing capacity of concrete-filled earthen shafts
OwnerJorj O. Osterberginventor
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
OwnerJorj O. Osterberginventor
Estimating the term…
A device which separately measures the skin friction and the load-bearing capacity of the earth at the bottom of a hole. An expansion device is in the bottom of the hole, with a shaft resting on top it. A pressurized fluid is pumped into the expansion device, via a coaxial pipe and rod, to fill and expand it. By observing the movements of the rod and pipe responsive to the expansion and relative to the ground surface, it is possible to record the pressure versus upward movement of the shaft and the pressure versus downward movement of the earth below the bottom of the shaft. The ultimate or maximum skin friction is indicated when the load-upward movement curve plotted from the data indicates no further increase in load with upward movement. The ultimate end bearing capacity is indicated when the load-downward movement curve indicates no further increase in load with downward movement. When the shaft has concrete poured down the hole, the expansion device may be a bellows-like affair with the rod connected to the bottom of the bellows and the pipe connected to the top. When the shaft is a driven pile, the expansion device is a massive piston which can withstand the driving forces.
A device for separately measuring the load-bearing capacity of an earthen substrate at the bottom of a hole and of the skin friction between the walls of the hole and a shaft in the hole, said device comprising a vertically acting expansion means resting flat on the bottom of said hole, means extending from the surface of the earth to said expansion means for transmitting a pressurized fluid from the top of the shaft to the expansion means at the bottom of the hole thereby expanding the expansion means to transmit upwardly and downwardly acting forces at the top and bottom of the expansion means, and means responsive to said transmission of fluid into said expansion means for measuring upward movement of the top of the expansion means to measure skin friction and for measuring downward movement of the bottom of the expansion means to measure underlying support capabilities.
A device for separately measuring the load-bearing capacity of an earthen strata at the bottom of a hole and the skin friction between a shaft and the wall of an earthen hole, said device comprising upper and lower spaced parallel expansion means joined at their peripheries to enable said expansion, whereby said expansion may move apart responsive to a pressurization of the space between said upper and lower expansion means, means for lowering said device to lie flat on the bottom of said hole, said lowering means including a coaxial pipe and rod extending from the upper surfaces of said upper and lower expansion means respectively, means for transmitting a pressurized fluid from the top through the pipe to the space between the upper and lower expansion means at the bottom of the hole, said pressurized fluid expanding said expansion means, and means for measuring upward movement of the pipe and downward movement of the rod responsive to the expansion which occurs when the fluid is transmitted into said expansion means.
A method of separately measuring skin friction and the supporting capacity of an underlying earthen area, said method comprising the steps of:
A device for testing the load-bearing capacity of a shaft in the earth, said device comprising a coaxial rod and pipe extending from the top of the earth down approximately the center of the shaft to the bottom of the shaft, an inflatable rubber-like doughnut associated with the bottom of said coaxial rod and pipe and positioned between the bottom of said shaft and the underlying earth, and means for detecting movement of the tops of said rod and pipe responsive to fluid pumped down said pipe to said rubber-like doughnut.
Dependencies are inferred from the claim text.