Parameters Affecting Screw Pile Capacity Embedded in Soft Clay Overlaying Dense Sandy Soil

Abstract

Abstract The screw piles application is constantly increasing due to their high efficiency and numerous advantages. Screw piles are supplying stability against compression, overturning moment, uplift tension, and horizontal loads. This investigation presents a set of model experiments performed on single screw pile embedded in soft clay soil over laying a sandy soil loaded in compression, at a constant strain rate. The sandy layer 20 cm thick was compacted in a test container of 30 cm diameter into four sublayers to attain a relative density of 70%. The 30 cm thick soft clay layer with Cu (undrained shear strength) 30 kPa was compacted in six sublayers on the sandy bottom layer. Three different pile length (30, 35 and 40 cm), single and double helix and pile without helix, (3D and 4D) helix diameter, (3 and 5) cm spacing between helix plate are used in this study. The experiment results showed that, the screw piles settlement for piles embedded in soft clay soil overlaying a sandy soil layer decreases (59-182)% with increasing depth of embedment in the sandy layer L/D from 35 to 40, number and diameter of helix those provide anchorage against settlement. The deeper screw piles with higher L/D ratios showed compressive capacity (24-55) times greater than the shallower piles (screw pile embedded in soft clay). In addition, screw piles demonstrated resistance to the applied compressive forces (9-16) times more than ordinary piles. The compressive force increases with rising number and diameters of helix plates.