Study on load transfer and resistance of large diameter deep embedded rock piles in complex strata

Journal Information

J. Hefei Univ. Tech. (Nat. Sci.), Jun. 2026, Vol. 49 No. 6: 813-820

DOI: 10.3969/j.issn.1003-5060.2026.06.014

Authors

LI Zibing $ ^{1} $, YIN Yonggao $ ^{2} $, CHEN Taotao $ ^{2} $, WANG Kehong $ ^{2} $, HE Min $ ^{2} $, XI Banglu $ ^{2} $

(1. Anhui Expressway Test and Research Center Co., Ltd., Hefei 230031, China; 2. School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei 230009, China)

Abstract and Keywords

Abstract: This study focuses on large diameter deep embedded rock piles of a rail-cum-road Yangtze River bridge under overload conditions. Traditional research approaches regarding the lateral friction resistance of rock-embedded piles assume that the pile-rock interface is a plane. However, it is proposed that in deep embedded rock foundations in thick rock strata, the pile-rock interface actually forms a rough surface with significant geometric variations. Therefore, it is necessary to consider the joint roughness coefficient (JRC) and the pressure exerted by the initial setting of the concrete against the surrounding rock (referred to as $ P_{hi} $) to evaluate the bearing capacity of the cast-in-place pile. By conducting indoor direct shear tests on concrete-rock interface samples, parameters for the pile-rock interface considering JRC $ ^{3D} $ and $ P_{hi} $ are obtained, and a numerical calculation model for the vertical load of rock-embedded piles is developed to analyze the lateral resistance at the pile-rock interface, as well as the load transfer mechanism and ultimate bearing capacity of the pile foundation under overload conditions. The following conclusions are drawn: when subjected to upper load conditions, the lateral resistance of the rock-embedded segment of large diameter deep embedded rock piles varies with depth, which differs from the assumption in pile design codes that the lateral friction resistance remains constant across the same stratum; during the formation of the pile-rock interface, the self-weight stress of the concrete slurry increases with the depth of the pile, significantly enhancing the depth effect of the interface. characteristics and, consequently, improving the allowable bearing capacity of the pile foundation. A modified formula for the mobilization coefficient of the lateral resistance, taking into account the squeezing effect of the pile foundation and the depth effect of the interface characteristics, is proposed. The research results may provide reference for the design of the large diameter deep embedded rock piles in complex strata under overload conditions. characteristics and, consequently, improving the allowable bearing capacity of the pile foundation. A modified formula for the mobilization coefficient of the lateral resistance, taking into account the squeezing effect of the pile foundation and the depth effect of the interface characteristics, is proposed. The research results may provide reference for the design of the large diameter deep embedded rock piles in complex strata under overload conditions.

Keywords: deep embedded rock piles; pile-rock interface; roughness; bearing characteristics; lateral resistance of pile body

作者信息

李子兵 $ ^{1} $，殷永高 $ ^{2} $，陈涛涛 $ ^{2} $，王克宏 $ ^{2} $，何敏 $ ^{2} $，奚邦禄 $ ^{2} $

(1. 安徽省高速公路试验检测科研中心有限公司, 安徽合肥 230031; 2. 合肥工业大学土木与水利工程学院, 安徽合肥 230009)

摘要和关键词

摘要: 文章以重载作用下某公铁两用长江大桥大直径深嵌岩桩为研究对象, 针对目前对嵌岩桩桩侧摩阻力的研究, 传统的做法认为在构造上桩-岩接触界面是一个平面, 提出了嵌入深厚岩石地层的桩基础在桩-岩界面会形成几何形态差异较大的粗糙面, 需要考虑界面粗糙度(joint roughness coefficient, JRC)及混凝土初凝期与围岩侧壁作用压力 $ P_{hi} $对灌注桩承载力的影响, 通过室内混凝土-岩样界面直剪试验获取考虑三维JRC与 $ P_{hi} $的影响下的桩-岩接触界面参数, 建立嵌岩桩竖向荷载下数值计算模型, 分析其桩-岩接触界面侧向抗力、重载作用下桩基的传力机理及极限承载力。结果表明: 大直径深嵌岩桩在承受上部重载作用时, 嵌岩段桩身侧向抗力沿桩深位置是变化的, 不同于桩基规范认为同一地层桩侧摩阻力是不变的假定; 在桩-岩界面成型中, 混凝土浆液自重应力随成桩深度增加而增加, 可大大提升桩-岩界面特性深度效应, 进而提升桩基容许承载力; 提出考虑桩基挤压效应和桩-岩界面特性深度效应的侧阻发挥系数修正公式。该研究成果对重载作用下复杂地层深嵌岩桩基础的设计具有一定参考意义。

关键词: 深嵌岩桩；桩-岩界面；粗糙度；承载特性；桩身侧向抗力

Funding

国家自然科学基金资助项目（52209127）；安徽省交通控股集团有限公司科技资助项目（JKKJ-2020-31）

合肥工业大学学报(自然科学版)

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