MODEL TESTS OF PULLING RESISTANCE OF HELICAL SCREW PILES

The authors conducted the pull-out loading tests on a helical screw pile in a calibration chamber where the two layered sand deposits with different relative densities were prepared. When the ultimate uplift resistance of the pile head occurs, the uplift displacement is equal to 7.5~10% of the diameter of the helical plate. Meanwhile, the helical plate, the bottom plate and the pile shaft forming the helical screw pile show the particular resistance-displacement curves. The helical plate resistance definitely increases with the embedment length while the bottom plate resistance beneath the helical plate tends to be nearly constant.