MEASUREMENT OF BEARING POWER OF CAST-IN-PLACE PILE HEAD

PURPOSE:To exactly measure the bearing power of a cast-in-place pile head by a method in which a steel tube having a slipping material on its inner surface is penetrated into an excavated pit, the cast-in-place pile is formed in the steel tube, and a pile axial direction load is applied to the upper end of the pile. CONSTITUTION:A steel tube 2 having a slipping material (a) such as asphalt- based materials, etc., on its inner surface is penetrated into a pit under the ground. A reinforcing bar cage and concrete are put in the steel tube 2 to form a cost-in-place pile B. Reaction piles C are placed on both sides of the pile B, and an oil-pressure jack E is provided between a horizontal member D fixed to the upper ends of the piles C and the upside of the pile B. A load test is made. Since the pile B is in an isolated state from the steel tube 2 by the slipping material (a), no skin friction forces act on the pile B, and therefore, the bearing power of the ground at the lower end of the pile can be measured exactly.