水平循环荷载下高桩基础受力性状模型试验研究

近海高耸结构基础承受风,浪,波流等水平循环荷载作用,受力变形性状十分复杂.在饱和粉土地基中完成了单桩和群桩的水平循环加载试验,揭示了单桩和群桩响应随循环加载的变化规律.试验结果表明循环加载使桩周土体产生累积塑性变形,桩-土体系水平刚度随循环次数增加不断下降;先期循环加载对后期加载的刚度有着明显影响;群桩中各基桩分担的水平荷载比例随循环加载发生重分配,前排桩的作用得到更多发挥;荷载循环效应对群桩的影响大于单桩.基于p-y曲线法引入循环效应系数以考虑荷载循环的影响,并将该方法与其它文献方法和试验结果作了对比验证.

Large-scale model tests on high-rise platform pile groups under cyclic lateral loads

Large-scale physical model tests are carried out to study the mechanical characteristics of high-rise platform pile groups subjected to cyclic lateral loads such as wave, tidewater and wind, etc. They are conducted in silts, which consist of nine steel-pipes in a closely-spaced arrangement. The response of pile groups and its variation under cyclic loading conditions are discussed. The results indicate that the cyclic loading produces plastic deformation within soil around piles. The lateral stiffness of pile-soil system decreases with cycling, and the lateral load carried by each pile is redistributed during repeated loading. The previous cyclic loading influences the stiffness of piles in the next loading stages. The effect induced by the cyclic loading is more important for group-pile than a single pile, which can be estimated by a multiplier based on the p-y curve method. Finally, a comparison between the calculated results and those obtained by other different methods is presented.