DEVICE FOR TESTING THE LOAD-BEARING CAPACITY OF CONCRETE-FILLED EARTHEN SHAFTS

摘要

Abstract of the DisclosureA device which separately measures the skin friction and the load-bearing capacity of the earth a the bottom of a hole. An expansion deviceis in the bottom of the hole, with a shaft resting on top it. A pressurizedfluid is pumped into the expansion device, via a coaxial pipe and rod, to filland expand it. By observing the movements of the rod and pipe responsive tothe expansion and relative to the ground surface, it is possible to record thepressure versus upward movement of the shaft and the pressure versus downwardmovement of the earth below the bottom of the shaft. The ultimate or maximumskin friction is indicated when the load-upward movement curve plotted from thedata indicates no further increase in load with upward movement. The ultimateend bearing capacity is indicated when the load-downward movement curve in-dilates no further increase in load with downward movement. When the shafthas 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 pipeconnected to the top. When the shaft is a driven pile, the expansion deviceis a massive piston which can withstand the driving forces.