水平循环荷载下嵌岩单桩基础受力特性试验研究  

Experimental study on characteristics of rock-socketed monopile under lateral cyclic loads

作　　者：袁煜晖 贺瑞[1,2] 朱元张 YUAN Yuhui;HE Rui;ZHU Yuanzhang(Key Laboratory of Minstry of Education for Coastal Disaster and Protection,Hohai University,Nanjing 210098,China;College of Harbor,Coastal and Offshore Engineering,Hohai University,Nanjing 210098,China;Three Gorges New Energy Offshore Wind Power Operation and Maintenance Jiangsu Co.,Ltd.,Yancheng 224055,China)

机构地区：[1]河海大学海岸灾害及防护教育部重点实验室,江苏南京210098 [2]河海大学港口海岸与近海工程学院,江苏南京210098 [3]三峡新能源海上风电运维江苏有限公司,江苏盐城224055

出　　处：《河海大学学报（自然科学版）》2024年第6期97-106,共10页Journal of Hohai University(Natural Sciences)

基　　金：国家自然科学基金项目(51879097,52271272)。

摘　　要：为保障嵌岩单桩基础海上风机的长期安全运行,试验研究了嵌岩单桩基础与土质地基单桩基础的受力特性差异,通过室内1g模型试验分析了地层性质、荷载条件对桩基承载力与受力特性的影响规律。结果表明:对于长径比较小的单桩基础,底部嵌岩时桩基水平刚度和承载力较无嵌岩情况提升显著;水平单调循环加载作用下,桩顶累积位移在开始的数十个循环中快速发展,后期逐渐趋于稳定;底部嵌岩时,桩顶的累积位移存在平衡状态;循环加载初期,桩基刚度均随循环荷载作用次数增加而增大,主要表现为砂土的振密效应,砂土密实后,结构刚度基本稳定;在循环荷载幅值较大时,强风化地基中的桩-岩界面在加载后期损伤脱离,桩基刚度有所下降;水平加载试验中,底部嵌岩单桩桩身弯矩最大位置始终高于无嵌岩情况;无论嵌岩与否,桩身最大弯矩位置均随荷载循环加载次数增加而有所下降;对于嵌入不同风化程度岩石的单桩,循环加载后再静力加载至桩基破坏,其最终破坏模式存在明显差异。To ensure the secure and prolonged operation of offshore wind turbines with rock-socketed monopile foundation,an experiment investigation is carried out to study the mechanical distinctions between such foundations and soil-based alternatives.The study involves an indoor 1 g model test to analyze the impact of stratigraphic property and loading condition on both the bearing capacity and mechanical properties of the rock-socketed pile.The research reveals that:The horizontal stiffness and bearing capacity of a rock-socketed monopile is significantly higher than that of a pure sand one with relatively a small length to diameter ratio.Under the horizontal monotonic cyclic loading,the cumulative displacement of the pile top develops rapidly in tens of cycles at the beginning,and tends to be stable in the later cycles;an equilibrium state exists for the cumulative pile-top displacement of rock-socketed monopiles.At the early stage of the cyclic loading,the stiffness of the pile foundation increases with the number of cyclic loads,mainly due to the vibrational density effect of sand,and the structural stiffness is basically stable after the sand is compacted.When the cyclic load amplitude is relatively large,the pile-rock interface is damaged and detached in the heavily weathered rock at the late loading stage,and the stiffness of the structure decreases.In the horizontal loading tests,the position of maximum bending moment of a rock-socketed monopile is always higher than that of a pure sand one,and the position of maximum bending moment of a pile decreases with the increase of cyclic loads whether the monopile is rock-socketed or not.A destructive static loading test is conducted subsequent to the cyclic loading tests,and the ultimate failure mode of the foundation obviously varies for the monopiles socketed in weathering rocks of different degrees.

关 键 词：海上风电 嵌岩单桩 循环荷载 模型试验 P-Y曲线 

分 类 号：TU473.1[建筑科学—结构工程] P752[建筑科学—土工工程]