Abstract: To reveal the bearing characteristics and loading transfer mechanisms of hard rock-socketed piles, the factors influencing the bearing performance of large-diameter rock-anchored piles in mountainous areas are investigated in this paper. Combined with the mechanized borehole project for a 500 kV transmission line in the western of Baoding, geological parameters of the rocks were obtained through quasi-static compression tests. Explicit nonlinear finite element(FE)methods were employed to conduct numerical simulations on the uplift and shear load-bearing properties, failure modes, and carrying mechanisms of large-diameter rock-socketed piles in hard rock area. The mechanical behavior of pile bodies- DOI:10.3969/j.issn.1000-1565.2024.06.001山区机械化成孔的大孔径硬岩嵌岩桩承载能力王敬德^1,2,张新春¹,刘增炜³,孙青松³,李北²(1.华北电力大学 能源动力与机械工程学院,河北 保定 071003;2.河北电力工程监理有限公司,河北 石家庄 050081;3.国网河北省电力有限公司 建设公司,河北 石家庄 050081)摘 要:为揭示硬质岩石的承载能力与荷载传递机制,结合保定西某500 kV输电线路的山区机械化成孔项目,对山区大孔径嵌岩桩承载性能的影响因素进行了研究.首先利用准静态压缩试验得到岩石地质参数.然后,采用显式非线性有限元方法对山区大孔径硬岩嵌岩桩的抗拔与抗剪承载特性、失效模式和受力机理进行数值研究,具体分析桩体在上拔和水平荷载作用下的力学性能,讨论了覆土层增加钢套筒对桩体水平极限承载力的影响.研究结果表明:在上拔荷载下,承载力主要由桩体侧摩阻力和桩体自重来承担,硬质岩层桩侧摩阻力占主导地位,约为总侧摩阻力的90%;在水平荷载下,桩身较大位移区域在桩身4 m内,弯矩最大值出现在距桩顶2~3倍桩径,覆土层增加钢套筒可明显提高桩体的水平承载极限.本文研究结果将对岩石地质山区大孔径嵌岩桩结构设计和机械化施工提供理论指导.关键词:嵌岩桩;硬质岩石地质;抗拔承载力;水平位移;有限元分析中图分类号:TU741 文献标志码:A 文章编号:1000-1565(2024)06-0561-10Bearing capacity of large diameter hard rock socketed pile with mechanized hole in mountainous areasWANG Jingde^1,2, ZHANG Xinchun¹, LIU Zengwei³, SUN Qingsong³, LI Bei²(1. School of Energy Power and Mechanical Engineering, North China Electric Power University, Baoding 071003, China; 2. Hebei Electric Power Engineering Supervision Co., Ltd., Shijiazhuang 050081, China; 3. Construction Company, State Grid Hebei Electric Power Co., Ltd., Shijiazhuang 050081, China)Abstract: To reveal the bearing characteristics and loading transfer mechanisms of hard rock-socketed piles, the factors influencing the bearing performance of large-diameter rock-anchored piles in mountainous areas are investigated in this paper. Combined with the mechanized borehole project for a 500 kV transmission line in the western of Baoding, geological parameters of the rocks were obtained through quasi-static compression tests. Explicit nonlinear finite element(FE)methods were employed to conduct numerical simulations on the uplift and shear load-bearing properties, failure modes, and carrying mechanisms of large-diameter rock-socketed piles in hard rock area. The mechanical behavior of pile bodies- 收稿日期:2024-04-23;修回日期:2024-09-05 基金项目:国家自然科学基金资助项目(11875014);河北省电力工程监理有限公司资助项目(SGTYHT/21-JS-223) 第一作者:王敬德(1990—),男,华北电力大学在读博士研究生,河北电力工程监理有限公司高级工程师,主要从事输电线路工程研究.E-mail:rqhdejd@163.com 通信作者:张新春(1980—),男,华北电力大学副教授,博士,主要从事输电线路工程研究.E-mail:xczhang@ncepu.edu.cn 第6期王敬德等:山区机械化成孔的大孔径硬岩嵌岩桩承载能力河北大学学报(自然科学版) 第44卷under uplift and horizontal loadings was discussed in detail. The effects of adding steel casings to the overburden layer on the horizontal ultimate bearing capacity of the piles were also studied. The results show that the bearing capacity mainly depends upon the side frictional resistance and the self-weight of the pile under uplift loadings. The side frictional resistance of the pile plays a dominant role in the hard rock formation, which is about 90% of the total side frictional resistance. Under horizontal load, the maximum displacement area of pile body is within 4 m, and the maximum bending moment will appear within 2—3 times diameter of the pile from pile top. The horizontal ultimate bearing capacity of the pile can be significantly improved by adding steel casing to the overlying soil layer. These results will provide theoretical guidance for the structural design and mechanized construction of large-diameter rock-socketed piles in rocky mountainous area.

Key words: rock-socketed pile, hard rock geology, ultimate pulling capacity, horizontal displacement, finite element analysis