输电线路板柱基础上拔试验研究

Experimental Study on Uplift Capacity of Pad and Chimney Foundation for Transmission Line

针对架空输电线路板柱基础承载性状、破坏机理和计算方法研究相对薄弱的问题,文章以红色黏土地基为例,开展了上拔荷载作用下的板柱基础承载性状试验。结果表明:上拔荷载—位移曲线形态与地基载荷试验曲线的形态相似,极限上拔荷载试验值略大于《架空输电线路基础设计技术规程》(DL/T5219—2014)计算结果 ;板柱基础上部土体的土压力随着上拔荷载的增大而增大,增大的幅度与埋深正相关,而板边缘上部位置土体的土压力增长幅度最大;在上拔过程中柱内钢筋及上底板内钢筋均承受拉力,且拉力随荷载增大而增大,下底板内钢筋则承受压力,其值随上拔荷载的增大而略有增大;达到极限状态时地表形成了较为连续的圆形破裂缝,其直径略小于依土重法计算的假定破裂面直径。研究成果对板柱基础承载机理研究及优化设计具有参考价值。

Studies of in-situ tests on bearing capacity and damage mechanism of pad and chimney foundation, as a common type of foundation for overhead transmission line, is rarely reported. A test of on the site of a red clay was completed on bearing capacity of board-pillar foundation subject to uplift load, and the results are shown as the shape of curve of relationship between uplift load and vertical displacement is similar to that for plate load test of foundation, and the value of ultimate limit of uplift load from in-situ test is a little higher than that calculated from design method in the "Technical code for foundation of overhead transmission line"(DL/T 5219-2014) and the earth pressure above the board increased with the uplift load added, especially the pressure up to the edge of the board most, and the increased range was positively correlated to the embedded depth and during the uplifting, rebar in the pillar and upper baseboard bore tension which was increased with the uplift load increased, while the rebar in the lower baseboard bore pressure which had a slight rise with the uplift load increased and ring crack formed on the ground surface when the foundation reached its ultimate limit, and the diameter was slightly smaller than that calculated from the soil-weight method of the Code. Results is beneficial to the bearing mechanism research and optimization of engineering design.