天津某项目长大桩检测实例分析与探讨

Analysis and discussion on testing of large diameter and super-long piles in a project in Tianjin

摘要:

基桩承载力与完整性检测是隐蔽工程验收的关键环节，通常于桩基设计阶段即规划好检测方法，在施工阶段安放好检测设施或解决好地基处理问题，以利于后续检测工作的顺利开展。大直径超长桩因设计承载力大、桩身情况复杂，对检测工作要求较高，更应遵循检测与设计同步的原则。本文所述天津某项目恰恰忽视了基桩检测的事前设计，致使长大桩检测遇到棘手问题。作者在有限条件下通过专业技术分析，利用多年实践经验，因地制宜制定检测方法措施，采取分步加载法解决了大吨位堆载试验对长大桩承载力的验证性试验问题，综合利用低应变法与高应变法解决了长大桩的完整性检测问题，为类似工程提供了宝贵经验。

关键词:长大桩;承载力检测;桩身完整性;堆载试验;低应变法;高应变法

Abstract:

Testing of bearing capacity and integrity of foundation piles is the key step in acceptance inspection of concealed works. Usually， the testing method is planned in the design stage of pile foundation with the testing facilities placed or the ground treated in the construction stage， so as to facilitate the smooth execution of subsequent testing. The large diameter and super-long pile has high testing requirements due to the large design bearing capacity and complex pile conditions； thus， the principle of synchronous testing and design should be followed. On a project in Tianjin， the very negligence of prior design of foundation pile testing led to difficulty in large diameter and super-long pile testing. Though the conditions were limited， with professional technical analysis and many years of practical experience， and through formulation of testing methods and measures according to local conditions， the author has completed the bearing capacity verification test on large diameter and super-long piles with large tonnage surcharge by the step-by-step loading method， and integrity test on large diameter and super-long piles by combination of the low-strain method and the high-strain method， which provides valuable experience for similar works.

Key words:large diameter and super long piles;bearing capacity testing;pile integrity;surcharge test;low-strain method;high-strain method