桩锚支护结构锚杆受力机理试验研究

Experimental research on stress mechanism of the anchor of pile-anchor supporting structure

为分析基坑开挖过程中桩锚支护结构的锚杆受力机理,结合西宁火车站综合改造工程的深基坑支护结构,对不同工况条件下锚杆的受力进行现场综合动态试验与监测。结果表明:在未施加预应力阶段,随着基坑的开挖,锚杆的锚固作用逐渐发挥,锚杆轴力沿锚固长度呈现先增大后减小的变化趋势,而摩阻力的分布则存在"中性点";对锚杆进行单循环加载时,锚头施加的荷载有所损失,锚杆轴力和摩阻力均沿锚固段长度逐渐减小;在施加预应力之后,锚杆轴力沿锚杆长度逐渐减小,随开挖深度的增加而逐渐增大,摩阻力沿锚固长度逐渐减小。所得结论可进一步完善锚杆的受力理论,为基坑支护的优化设计及施工提供参考性建议。

To study the stress mechanism of anchors of pile-anchor supporting structure in the process of foundation pit excavation,engineering example of supporting structure of deep foundation pit in Xining railway station renovation project was used. Integrated field experiment and monitoring on stress of anchors under different working conditions were carried out. The results show that anchoring effect of the anchor play the role gradually with the pit excavation at the stage with absence of pre-stress,and axial force of the anchor decreases after increase along anchoring length while the neutral point exists on the distribution of frictional resistance. At the stage of single cyclic loading,the applied loading in the anchor head lose,the anchor axial force and frictional resistance decrease along anchoring length. After application of pre-stress,axial force of the anchor gradually decreases along anchoring length and increases with the excavation depth. Frictional resistance decreases along anchoring length and the variation is obvious at the back of the anchoring length. The obtained conclusions can further improve stress theory of the anchor and provide reference for the optimization design and construction of foundation fit supporting.