The Behavior of Tapered and Step-Tapered Piles under Lateral Load

The present study is an experimental investigation to determine the behavior of tapered and step-tapered piles in sand (cohesionless soil) under horizontal loads. A series of lateral loading tests were conducted on the modeled tapered and step-tapered piles with varying sections equal to taper angles of 0.5°, 1°, 1.5°, 2°, and segments of 2-segments, 3-segments, and 5-segments respectively. A large experimental facility was established to test the model piles. The testing facility consists of a model steel tank containing soil and a provision for applying an incremental lateral load. The pile was measured along its length to determine its behavior with depth. Tests were performed to failure to investigate the ultimate lateral load capacity and deflection. The results were compared with those of uniform-diameter piles to determine the performance of tapered and stepped piles. The results showed that the lateral capacity of both piles was significantly improved compared with that of the uniform-diameter pile. In addition, it was found that there exists an optimum taper angle and segments for tapered and step-tapered piles, which are in the range of 1° – 1.5° for tapered piles and 3 – 5 segments for step-tapered piles. It was concluded from the study that tapered and step-tapered piles have an increased lateral load-carrying capacity with a better distribution of materials, leading to economic benefits.