PURPOSE: To investigate the bearing power of a pile simply by inserting a pressure pipe, upper and lower sections of which have jacks, into the hollow pile sunk into the ground and applying pressure to the base of a pile pit while measuring the pressure at the base of the pile pit and the jacks.

CONSTITUTION: A nose blocking plate 2 is installed and sunk at the nose of a pile 1, a pressure pipe 3, a lower end of which has a jack 4 for forcing and an upper end of which has a jack 6 for loading, is inserted into the pile 1 while a drawing bar 11 is disposed in upright to the upper end section of the pile 1, and a pressure-receiving plate 12 abutted against the jack 6 for loading is fixed. Pressure water is forwarded to both jacks 4, 6 from a pump 18, and the pressure and the displacement of the push surfaces of the jacks and a pile head are measured respectively by a pressure gauge 21 and dial gauges 31, 33. The pressure pipe 3 and the jack 4 for forcing are pulled up after the load test, and concrete is placed in the pile 1.