九桩厚承台室内外试验分析与设计探讨

摘要

To study the load-bearing mechanism of deep pile caps that are widely used in large-scale bridge constructions, a nine-pile double thin-wall pier cap was tested to failure, and the bearing behavior of a nine-pile double thin-wall piers cap during the construction period was inspected. The laboratory and field tests indicated that the deep pile caps did not behave like conventional flexural members, and that the load bearing mechanism under line load conformed to a strut-and-tie model. Zones of concrete with primarily unidirectional compressive stresses are modeled using compression struts and tension ties as the principal reinforcements. The line load applied to pile cap can be reduced to concentrated load using the equivalent load method, to form a uniform strut-and-tie model which can be designed using the procedure in the relevant code.%为研究大型桥梁工程中常见的厚桩基承台受力机理,首次对1个九桩双薄壁墩厚承台模型进行室内破坏性加载试验,对承台的受力全过程进行了研究,并对某大型桥梁九桩双薄壁墩承台进行了施工全过程的现场实测.室内外试验结果均表明,厚承台的受力与传统的受弯构件不同,线荷载作用下承台的受力机理符合以带有主要单向性压应力的混凝土区域为压杆,主受力钢筋为拉杆的空间桁架模型.通过荷载等效,将作用在承台上线荷载等效为集中荷载,建立了统一的空间桁架模型,进而可采用有关规范给出的设计方法设计.