摘要
为研究含砂卵石地层中预应力锚索的加卸载工作性能,依托某基坑支护工程,对不同自由段和锚固段长度的预应力锚索进行了现场拉拔试验,同步测试了各锚索的位移变化。试验结果表明:本级位移和累计位移随加载荷载的增大保持连续增长,拉拔位移和锚索的自由段及锚固段长度紧密相关。归纳提出了含砂卵石地层下预应力锚索P-S曲线的指数模型,并对归纳的模型参数适用性进行了检验分析。预应力锚索卸载后的位移包括锚固体的塑性位移、锚固体和含砂卵石层间的滑移位移,以及自由段钢绞线的塑性拉伸形变。增加长锚索的锚固段长度可以提高锚索结构对较大拉拔荷载的位移控制性能,而短锚索在使用时应该保证其最短锚固段长度。研究结果可为西北地区卵石地层的支护工程设计和施工提供经验和借鉴。
In order to analyze the loading and unloading performance of prestressed anchor cables in sandy pebble stratum,based on a foundation pit support project,the field pull-out tests of prestressed anchor cables with different lengths of free section and anchor section were carried out,and the displacement changes of each anchor cable were measured synchronously.The test results show that the displacement and cumulative displacement at this level keep continuous growth with the increase of loading load,and the pull-out displacement is closely related to the length of free section and anchorage section of anchor cable.The exponential model of P-S curve of prestressed anchor cable under sandy pebble stratum is summarized and proposed,and the applicability of the summarized model parameters is tested and analyzed.The displacement of prestressed anchor cable after unloading includes the plastic displacement of anchor body,the sliding displacement between anchor body and sand pebble layer,and the plastic tension of steel strand in free section.Increasing the length of the anchorage section of the long anchor cable can improve the displacement control performance of the anchor cable structure under large load,and the shortest anchorage section length of the short anchor cable should be guaranteed when it is used.The research results can provide experience and reference for the design and construction of the support engineering of the pebble layer in Northwest China.
作者
孙伟红
马亮
杨鑫
SUN Weihong;MA Liang;YANG Xin(Gansu Academy of Building Research(Group)Co.,Ltd.,Lanzhou,Gansu 730030,China)
出处
《水利与建筑工程学报》
2022年第4期155-161,共7页
Journal of Water Resources and Architectural Engineering
基金
甘肃省住房和城乡建设厅2019年建设科技项目计划“BIM技术在兰州市区复杂环境深大基坑中的研究与应用”(JK2019-06)。
关键词
含砂卵石
预应力锚索
拉拔
荷载
锚固
sandy pebble
prestressed anchor cable
pull-out
load
anchorage
