水平循环荷载下砂土海床中超大直径单桩临界埋深确定方法研究  

DETERMINATION ON CRITICAL DEPTH OF MONOPILE IN SAND UNDER CYCLIC HORIZONTAL LOAD

作　　者：章刘洋 朱斌[1,2] 孙永鑫 王路君 ZHANG Liuyang;ZHU Bin;SUN Yongxin;WANG Lujun(MOE Key Laboratory of Soft Soils and Geo-Environmental Engineering, Zhejiang University, Hangzhou 310058, China;Institute of Geotechnieal Engineering, Zhejiang University, Hangzhou 310058, China;Economic ＆ Technology Research Institute, State Grid Shandong Electric Power Company, Jinan 250022,China)

机构地区：[1]浙江大学软弱土与环境土工教育部重点实验室,杭州310058 [2]浙江大学岩土工程研究所,杭州310058 [3]国网山东省电力公司经济技术研究院,济南250022

出　　处：《工业建筑》2018年第6期91-95,134,共6页Industrial Construction

基　　金：国家自然科学基金项目(51679211)

摘　　要：超大直径单桩是目前海上风机最常见的基础形式,承受风压、波浪等循环荷载的耦合作用,其变形机理与传统的常规直径基桩存在较大差异,目前国际上还没有成熟的设计理论。在保证基桩服役性能的同时需考虑经济性,因此确定基桩的临界埋深具有重要意义。基于砂土割线刚度衰减模型,开发了相应的桩土水平循环相互作用分析有限元子程序;根据福建平潭标准砂三轴循环剪切试验率定刚度衰减模型参数,进行基桩水平静力和循环变形三维数值分析,并将计算结果与超重力离心模型试验结果进行对比验证。在此基础上针对福建平潭海上风电场5 m直径的超大直径单桩,计算不同循环次数下的桩身变形特性,并基于不同的判断准则确定其临界埋深。最终建议以基桩泥面处侧向变形达到最小值时的埋深作为基桩临界埋深,相应的基桩临界埋深为8倍桩径。Monopiles are the most widely adopted foundation system for offshore wind turbines（OWTs） in the world,which are mainly subjected to the coupling action of cyclic loads such as wind and waves. The deformation mechanism of monopile is different from that of traditional small diameter pile foundation,there isn＇t any mature design theory yet. To ensure the performance of monopiles while considering economical availability,the critical depth of pile needs to be determined. Based on the secant stiffness degradation model of sand,a corresponding subroutine in finite element program was developed. An analysis model of pile-soil interaction under cyclic loading was established based on the parameters validated from cyclic triaxial tests. The results of FE model were compared with the results from centrifuge model test to verify their correctness. For the case in Fujian Pingtan offshore wind farm,the cyclic deformation characteristics of monopiles with diameter of 5 meters were calculated,and their critical depth were determined based on different design criterias. It was suggested that the critical depth could be reached when the monopile＇s lateral deformation at the mud surface was minimal,and the corresponding critical depth was 8 times of pile diameter.

关 键 词：超大直径单桩 水平循环荷载 循环衰减 临界埋深 

分 类 号：TU476[建筑科学—结构工程]