Tip Shape Effect on Screw Pile Installation and Ultimate Resistance

In the field of deep foundations, the screw pile is one of the new ways of construction that can support infrastructure against extreme weather events. Moreover, its eco-friendly installation mechanics that involve quick installation, minimum noise and vibration; no wastage of material and reusability makes it more efficient than conventional piling techniques such as concrete piles which involves noise, consumption of natural resources, and wastage of materials. However, the use of screw pile in the dense ground with large helix is still a concern as higher torque and pushing force is required, which sometimes exceeds the limits of machinery. In this regard, the present study focused on the effect of helix tip shape on the installation torque and force under dense ground conditions. In addition to this, the effect of tip shape on ultimate resistance also studied. To investigate these effects, model-scale pile load tests are conducted. Three kinds of pile tip shapes, i.e., flat, cone, and cutting-edge ends are considered in this study. Toyoura sand is used as a model ground. Ground disturbance due to pile installation also monitored at various distance from the edge of the pile. To check the effectiveness of the screw pile, its results compared with the results of the straight pile having the same shaft diameter under similar ground conditions. The test results indicated that the overall performance of the screw pile with cutting-edge is better than other tip shape piles, and also better than straight shaft pile in terms of installation force, torque, surrounding ground disturbance, and ultimate resistance.