基桩竖向抗压静载荷试验若干关键问题的研究

Research on Several Key Issues of Vertical Compressive Static Load Test of Foundation Piles

摘要:

基桩竖向抗压静载试验是工程桩验收的核心手段，也是确定单桩竖向抗压极限承载力的可靠方法。基于对《建筑基桩检测技术规程》（JGJ 106—2014）、《公路工程基桩检测技术规程》（JTG/T 3512—2020）、《水运工程基桩试验检测技术规程》（JTS 240—2020）等规范的梳理，重点阐释Q-s曲线陡变型、缓变型判定标准与误判原因，剖析缓变型曲线基桩极限承载力不同判定方法及规范差异。以武汉绿地中心超高层大直径嵌岩灌注桩为实例，揭示桩身弹性压缩对桩顶沉降的影响规律及其在长桩承载力评价中的工程意义，明确地面桩与坑底桩的本质区别及修正。研究表明，做好试验筹备、严控试验流程、优选坐标比例、计入长桩弹性压缩，可有效提升静载试验结果精准度与可靠性。

Abstract:

The vertical compressive static load test of foundation piles is the core means for the acceptance of engineering piles and is also a reliable method for determining the ultimate vertical compressive bearing capacity of a single pile. On the basis of sorting out the codes such as Technical Code for Inspection of Building Foundation Piles (JGJ 106—2014), Technical Code for Inspection of Foundation Piles in Highway Engineering (JTG/T 3512—2020), and Technical Code for Test Inspection of Foundation Piles in Water Transport Engineering (JTS 240—2020), the determination criteria and misjudgment reasons for the steep and slow variation types of the Q-s curve are specially explained, and the differences in various determination methods and standards for the ultimate bearing capacity of slowly varying curve foundation piles are analyzed. Taking the super-high-rise large-diameter rock-embedded cast-in-place piles of Wuhan Greenland Center as an example, the influence law of elastic compression of the pile body on the settlement of the pile block and its engineering significance in the bearing capacity evaluation of long piles are revealed, and the essential differences and corrections between ground piles and pit bottom piles are clarified. Research result shows that proper test preparation, strict control of the test process, optimal selection of coordinate ratios, and inclusion in the elastic compression of long piles can effectively enhance the accuracy and reliability of static load test results.