Research on self-balancing test pile detection technology for large-diameter drilled piles of extra-large bridges crossing navigable waterways
跨通航河道特大桥大直径钻孔灌注桩自平衡试桩检测技术研究

摘要

针对跨通航河道特大桥地质条件复杂，试桩涵盖陆上引桥、水中引桥及水中主桥桩基的工程特点，采用超声波成孔质量检测、声波透射法桩身完整性检测与自平衡法桩基静载试验相结合的成套检测技术，完成3根大直径钻孔灌注桩试桩检测。介绍试桩方案设计、荷载箱与钢筋应力计埋设工艺、现场测试流程，阐述自平衡试验加载控制、桩身轴力、分层侧摩阻力以及极限承载力的计算思路。结果表明，该组合检测方案可同步评价成孔质量、桩身完整性与桩基承载性能，获取各土层实测侧摩阻力参数；潮间带复杂工况条件下，荷载箱安装精度、测试线缆防护、成桩灌注工艺是保障自平衡试桩成功实施的关键，可为同类地区大直径钻孔灌注桩试桩工程提供借鉴。

Abstract

Considering the complex geological conditions of extra-large bridges crossing navigable waterways and the engineering characteristics of the test piles covering the land approach bridge, water approach bridge, and water main bridge pile foundations, a complete set of detection technology combining ultrasonic hole quality detection, acoustic transmission method for pile integrity detection, and self-balancing pile static load test was adopted to complete the detection of 3 large-diameter drilled pile test piles. The test pile scheme design, load box and vibrating-wire steel bar stress gauge embedding technology, and on-site testing process were introduced. The loading control of self-balancing test, pile axial force, layered side friction resistance, and ultimate bearing capacity calculation ideas were expounded. The results show that this combined detection scheme can simultaneously evaluate hole quality, pile integrity, and pile foundation bearing performance, and obtain the measured side friction resistance parameters of each soil layer. Under complex conditions of intertidal zone, the installation accuracy of the load box, the protection of test cables, and the construction and pouring process of the pile are the key to ensuring the successful implementation of the self-balancing test pile. This can provide a reference for similar large-diameter drilled pile test pile projects in other regions.