青藏交直流联网工程装配式基础抗压性能试验

Compressive Performance Test of Precast Concrete Assembly Foundation for Qinghai-Tibet AC/DC Grid Interconnection Project

通过监测下压加载试验过程中基础构件位移、基底土压力以及连接件应力变化,研究了青藏交直流联网工程部分冻土地基所应用的预制装配式基础在下压荷载作用下的协同工作性能。试验结果表明:(1)下压荷载作用下预制装配式基础荷载-位移曲线变化可分为弹性、弹塑性屈服两个阶段,基础立柱和底板连接法兰盘、底板之间连接缝附近位移量及其变化规律与基础顶部基本一致,预制基础整体承载性能好,能够满足青藏交直流联网工程杆塔基础承载性能要求。(2)预制装配式基础在下压荷载作用下,底板连接槽钢承受拉应力作用,设计荷载范围内均呈弹性应力状态,拼装底板以拼装缝为轴,呈2边向上弯折趋势,基础底板外边缘处角点沉降位移量小于基础顶部,基础底板接触压力变化规律不同。但下压位移量和基底土压力的差异在基础整个承载过程中均呈有限和规律性发展,基础各组成部件具备协同工作、共同承载的能力。(3)下压荷载作用下,基础拼装间隙、拼装过程中螺帽拧紧程度不同以及基础预制加工误差是预制装配式基础共同工作性能的主要影响因素。

The precast concrete assembly foundation for Qinghai-Tibet AC 750 kV/DC±400 kV grid interconnection project in frozen soil area was tested under compression load. The mechanical co-working properties for the different parts of the foundation were analyzed based on the monitoring results of structural displacement,soil pressure,and fitting stress.Under compression load,both the displacement and the changing regularity of the ring flange connecting the column and the bottom slab and the joint seam of the two consolidated bottom slabs comformed with that of the top plane of the foundation. Two stages of elastic and elastic-plasticity were observed according to load-diplacement curves of the foundation.The stress of the channel beams increased with the compression load and were found in elastic stress status.Under the compression load,the two edges which were parallel to the the joint seam of two consolidated foundation slabs had a tendency to upwarping. However the displacement of all angular measuring points were less than that of the top plane of the foundaiton.The diplacemnet and the stress of the different connected parts redistributed until the new banance developed.As a result,the different connected parts of the precast concrete assembly foundation co-operated to carry the compression load.The structrual characteristic of the assembly foundaiton,the gaps among the assembly parts,the discrepance of the nut screwing up and the mismathing tolerance during consolidating were the key factors to determine the performance of the foundation.Under compression load,all structural parts of precast concrete assembly foundation had good entirety.