Investigation of Lateral Resistance Capacity of Inclined Helical Pile Group in Sandy Soil under Cyclic Loading

Abstract

ABSTRACT Inclined helical piles are one of the types of deep foundations used to resist loads resulting from tension, lateral external loading, and axial compression. Despite significant progress in helical pile manufacturing and application, particularly in wind turbines and power transmission towers, few studies on their side behavior have been conducted. In this research, the response of inclined helical and ordinary pile groups (2×1), (1×2), and (3-pile) under lateral cyclic load (CLR) study with the various pile inclination angles (5°, 10°, and 15°), the spacing of the piles to the diameter of the helix (S/Dh = 3), pile diameter (10 mm), and various pile embedded lengths to the diameter of the shaft (L/d = 33, and 26) by using single and double helix for inclined helical piles. All inclined pile group models are embedded inside sandy soil at a relative density of 65% and tested under the impact of a pure two-way symmetrical side periodic load with a natural frequency of 0.2 Hz. In this work, various parameters have been studied like the impact of configuration, the impact of pile inclination angles, the impact of helix number in the inclined helical pile and compared with the inclined ordinary pile, and the impact of embedded length for the inclined helical pile under the impact of various levels for periodic load proportion and with the use of a cyclic number until 100. VI The results show that increasing the pile inclination angle significantly affects lateral resistance. At a 60% cyclic load ratio, increasing the inclination angles of the piles in all groups from (5°) to (10° and 15°) for the same pile embedded length increases lateral resistance by about (11.5-22.5%) and (21-39%), respectively. The side resistance is also affected by the arrangement of identical piles in the group; the inclined pile group (1×2) has a higher lateral resistance than the inclined pile group (2×1), about (28%, 24%, and 8%) for single helix-pile, double helix-pile, and ordinary pile, respectively. The inclined helical piles showed better performance than inclined ordinary piles during side cyclic load influence, as the inclined ordinary piles gave side deflection larger than the inclined helical piles with a proportion of (11 100) % at various cyclic load ratios, and the double helix-piles showed better performance compared with the single helix-piles during periodic side load impact, as the double helix-piles gave side resistance larger than the single helix-piles by a proportion of (4 23%) at various cyclic load ratios.