CFG桩复合地基承载力检测方法讨论与实例分析

Case study and discussion on test method for bearing capacity of composite foundation with CFG piles

CFG桩复合地基技术目前已广泛应用于高层建筑地基处理,但实际工程中CFG桩施工问题频发,故引起对其承载力检测方法的关注,相关规范也伴随工程实践和总结逐渐成熟起来。《建筑地基处理技术规范》(JGJ79—2002)只要求进行复合地基静载荷试验以检测复合土层承载力,《建筑地基处理技术规范》(JGJ 79—2012)增加了复合地基增强体单桩静载荷试验,要求必须将增强体单桩承载力作为检测的一项重要指标。本文中某高层办公楼,在新版规范(2012版)未使用之前,超前进行了复合地基增强体单桩静载荷试验,试验结果的确有不合格增强体单桩,即在所检测的5根单桩中,2根单桩承载力未达到设计要求。为此,讨论了在进行CFG桩复合地基设计时,进行增强体单桩静载荷试验的必要性。

Composite foundation technology with CFG piles has been widely used in high-rise building foundation treatment. But engineering accident was happened frequently in the practical construction processes of the CFG piles.Thus,its bearing capacity test method has drawn greater attention,and the relevant specifications are also gradually mature with engineering practice and summarizes. It only requires load test on composite foundation to test bearing capacity of composite soil according to Technical code for ground treatment of buildings(JGJ 79—2002). The content of the Technical code for ground treatment of buildings(JGJ 79—2012) has added load test on single pile of composite foundation,and it rules bearing capacity of single pile as an important indicator of detection. In this article,during the construction of a high-rise office building,the load test was carried on the single pile of composite foundation before the new standards(2012 edition) was used. The test result shows that there are unqualified reinforcing single piles indeed.Namely,in the five tested reinforcing single piles,the bearing capacity of two piles did not reach the design requirements.Thus,in this paper,the necessity of enhancing load test on single pile of composite foundation for the design of composite foundation with CFG piles has been discussed.