隧道开挖对邻近单桩竖向受力特性影响

Effects of tunneling on vertical bearing behaviors of adjacent single pile

在分析隧道开挖对邻近单桩竖向受力特性影响时,基于荷载传递法和Winkler地基模型,利用两阶段分析法通过迭代求解给出隧道开挖与邻近单桩相互作用的弹塑性解答。通过与离心机试验的短期和长期试验结果的对比,分析了隧道开挖对邻近单桩的竖向影响,从而验证该方法的合理性和适用性。讨论了隧道开挖情况下隧道中心线距地表的距离、隧道中心线与桩轴线的距离、平均地层损失比、桩长、桩径、桩身强度6种因素对邻近单桩竖向受力特性的影响,提出隧道开挖对邻近单桩的竖向受力特性的影响规律。结果表明:随着隧道中心线距地表距离的增加,桩身沉降和桩身轴力先增大然后逐渐减小;随着隧道轴线与桩轴线距离的增加,桩身沉降逐渐减小,桩身轴力增大到一定值后逐渐减小;随着平均地层损失比的增加桩身沉降不断增大,桩身轴力逐渐增大到稳定值。

Based on load transfer method and Winkler model,an elastoplastic solution of tunnel-pile interaction is given by the two-stage method to analyze the vertical behavior of adjacent single pile due to tunneling.The long-term and the short-term vertical behaviors of adjacent single pile are analyzed.The results are compared with that obtained from some existing centrifuge model tests,and then a good agreement is observed.The influences of the distance between tunnel center line and the ground surface,the distance between tunnel center line and the pile axis,ground loss,pile length,pile diameter and pile strength on the vertical behavior of adjacent single pile due to tunneling are analyzed;and the influence regularity is presented.The results show that：（a） the distance between tunnel center line and the ground surface increases,the pile settlement and pile axis force firstly increases and then gradually decreases;（b） the distance between tunnel center line and the pile axis increases,the pile settlement decreases gradually,the pile axis force increases to a certain value and then gradually decreases;（c） with the increase of ground loss,the pile settlement is continuously increasing,the pile axis force gradually increases to a stable value.