Yang Tingting, Zheng Weicheng, Xie Yongli, Zhang Hongguang, Yue Xiabing
School of Highway, Chang'an Univ., Xi'an 710064, China.
Heliyon. 2023 Oct 11;9(10):e20887. doi: 10.1016/j.heliyon.2023.e20887. eCollection 2023 Oct.
Screw-shaft piles have seen extensive adoption in construction and railroad engineering, due to their superior enhanced bearing capacity and cost-effectiveness. While monopiles have been thoroughly examined, composite foundations that include screw-shaft piles have not been studied as extensively. Proper determination of geometric parameters for both the piles and the cushion is a critical aspect of successful design. This paper introduces a comprehensive examination that merges indoor experiments with numerical simulations, aiming to evaluate the bearing capacity, settlement characteristics, and force characteristics of screw-shaft piles under a variety of conditions. This study scrutinizes key components, such as root diameter, pitch, cushion modulus, and the threaded portion's proportion. The research outcomes offer crucial insights for optimizing the design parameters of screw-shaft pile composite foundations. The results indicate that the side resistance of screw-shaft piles initially increases with the threaded section's length, stabilizing at an optimal length of approximately 0.44-0.55 times the pile length (L). Furthermore, although decreasing the pitch improves bearing capacity, it also introduces variations in pile material usage, with optimal bearing performance noted at a pitch approximately equal to the diameter (D). Moreover, screw-shaft piles with thread widths ranging between 0.58D and 0.67D show a significant decrease in stress concentrations, approximately 22 % less than those with a width of 0.5D. By setting the cushion modulus within the 40 MPa-60 MPa range, reduced settlement and optimal pile-soil stress ratios were achieved. These research outcomes provide critical insights into optimizing screw-shaft pile composite foundation design parameters, serving as valuable guidance for designers and engineers in diverse civil engineering projects.
螺旋桩因其卓越的承载能力提升和成本效益，在建筑和铁路工程中得到了广泛应用。虽然单桩已得到充分研究，但包含螺旋桩的复合地基尚未得到如此广泛的研究。正确确定桩和垫层的几何参数是成功设计的关键环节。本文引入了一项将室内试验与数值模拟相结合的全面研究，旨在评估螺旋桩在各种条件下的承载能力、沉降特性和受力特性。本研究仔细考察了关键要素，如桩根直径、螺距、垫层模量以及螺纹部分的比例。研究结果为优化螺旋桩复合地基的设计参数提供了关键见解。结果表明，螺旋桩的侧阻力最初随螺纹段长度增加，在约为桩长（L）的0.44 - 0.55倍的最佳长度处趋于稳定。此外，虽然减小螺距可提高承载能力，但也会导致桩材料用量的变化，在螺距约等于直径（D）时观察到最佳承载性能。而且，螺纹宽度在0.58D至0.67D之间的螺旋桩应力集中显著降低，比宽度为0.5D的螺旋桩低约22%。通过将垫层模量设置在40MPa - 60MPa范围内，实现了沉降减小和最佳桩土应力比。这些研究结果为优化螺旋桩复合地基设计参数提供了关键见解，为各类土木工程项目的设计师和工程师提供了有价值的指导。
