盾构隧道近接侧穿引起桥梁桩体的变形规律

Law of Bridge Pile Deformation Induced by Shield Tunnel Side-passing in Proximity

目的:当盾构隧道侧穿临近桥梁的桩体时,会引起桩体发生一定的竖向变形和水平变形,因此有必要对桥梁桩体的变形规律进行研究。方法:建立数值计算模型,并进行可靠性验证;分析8根桩体的水平变形量及沉降量;基于数值计算模型分析盾构隧道施工时,各桩体x向水平变形量、y向水平变形量及沉降量;分析盾构施工桩体x向水平变形量的影响因素;对比分析盾构施工对各桩体实际沉降量的影响。结果及结论:距离左线盾构隧道最近的1号桩的沉降量最大,2号桩—8号桩的沉降量显著小于1号桩;右线盾构隧道施工产生的扰动对距离右线盾构隧道较远的桩体影响较小;盾构侧穿桥基对桩体水平x向的变形影响最为显著;随着盾构隧道直径的增大,桩体的最大水平变形逐渐增大;随着隧道埋深的增加,桩体的x向最大水平变形量先增大后逐渐减小。盾构侧穿过程会导致桩基产生较大的沉降,贯通后,土体负摩阻力将会消失,进而使得桩体产生一定的回弹。

Objective:When a shield tunnel passes bridge piles on the side in proximity,vertical and horizontal deformation can be caused in the piles.Therefore,it is necessary to study the deformation law of bridge piles under such circumstances.Method:A numerical calculation model is established and validated for reliability.The horizontal deformation and settlement of eight piles are analyzed.Based on the numerical calculation model,the x-direction horizontal deformation,y-direction horizontal deformation,and settlement of each pile during shield tunneling are analyzed.The influencing factors of shield tunneling pile x-direction horizontal deformation is investigated.The impact of shield tunneling on the actual settlement of each pile is compared and analyzed.Result&Conclusion:The No.1 pile that is closest to left-line shield tunnel demonstrates the largest settlement,while the settlements of piles No.2 to No.8 are significantly smaller than that of pile No.1.The disturbance caused by right-line shield tunneling had a minor impact on the piles farther away from the right-line shield tunnel.Shield tunnel side-passing bridge foundation has the most significant impact on pile horizontal x-direction deformation.As the shield tunnel diameter increases,the pile maximum horizontal deformation gradually increases.As the tunnel buried depth increases,the pile maximum x-direction horizontal deformation initially increases and then gradually decreases.The shield tunnel side-passing process will lead to evident settlement of pile foundation,and after passing through the soil,the negative skin friction would disappear,resulting in a certain amount of rebound in the piles.