超大直径嵌岩桩沉降长期效应研究及实测

RESEARCH ON LONG-TERM EFFECT OF LARGE-DIAMETER ROCK-SOCKETED PILES AND FIELD MEASUREMENTS

深圳平安金融中心超高层建筑的桩基础为超大直径嵌岩端承桩。由于混凝土材料的收缩及徐变特性,非荷载因素引起的桩身压缩及桩顶沉降不容忽视。为探究收缩徐变等非荷载因素对该工程超大直径桩长期变形的影响,借助SAP 2000有限元软件,运用工程中常采用的混凝土时变模型对施工全过程的桩基沉降进行了分析和预测,并与实测结果进行对比。结果表明:对于大直径端承桩,考虑混凝土材料的收缩徐变对桩基沉降预测是合理和必要的。常用的欧洲标准CEB-FIP 90、美国标准ACI 209R-92和GL2000等混凝土收缩徐变模型均能给出与实测结果相近的预测结果。

Shenzhen Ping’an Financial Center is a super-high-rise building in China.The pile foundation of the project is rock-socketed end-bearing piles with a super large diameter.Due to the creep and shrinkage of concrete materials,the compression of pile body and the settlement of pile top caused by the creep and shrinkage of concrete should not be ignored.In order to explore the influence of non-load factors on the long-term settlement of super-large diameter piles in this project,the settlement of pile foundation in the whole construction process of this project was analyzed and predicted by using SAP 2000,a finite element software.During the analysis some time-dependent volume varying models of concrete were adopted to reflect the time-varying characteristics of the concrete in the superlarge diameter piles.To check the rationality of the calculation results,comparison was made between the calculation results and the measured results.The results showed that it was reasonable and necessary for large diameter endbearing pile to predict the settlement of pile foundation considering the creep and shrinkage property of concrete.The frequently used models,such as CEB-FIP 90、ACI 209R-92 and GL2000,could give a correct prediction closed to the measuring results.