大直径超长混凝土灌注桩受力特性试验研究

Experimental study on stress characteristics of super-long large-diameter bored piles

选取郑州市某32层高218.5 m建筑物的3根大直径超长灌注桩进行静载荷试验,并对桩的荷载与沉降的关系及桩身应力测试结果进行了分析.结果表明,大直径超长灌注桩为纯摩擦桩,桩侧摩阻力大小取决于桩土相对位移大小和桩周土的种类、密实程度等因素,桩顶沉降主要来自于桩身压缩和压屈变形,无刚体位移,采取无限制增加桩长的方法很难达到提高桩基承载力的目的.

Static loading tests were performed on 3 super-long large-diameter bored piles of a 32-storey building with the height 218.5 m in Zhengzhou City. The analysis of the relationship between the loads and settlements of piles and the test results of pile stresses shows that super-long large-diameter bored piles are pure friction piles, the lateral friction along pile bodies depends on the relative displacement between soil and piles and the types and compactness of soils around piles, and that with negligible rigid body displacement, the settlement at the top of piles is mainly induced by compressive strain and buckling strain of pile bodies, therefore it is difficult to improve the bearing capacity of pile foundation only by increase of pile length unlimitedly.