浅埋超大直径盾构近穿既有高架桩基的影响  

Effect of a Shallowly Buried Super-large-diameter Shield Tunnel Closely Crossing Existing Pile Foundations of a Viaduct

作　　者：苏稚寅 谢家冲 王子怡 SU Zhi-yin;XIE Jia-chong;WANG Zi-yi(Shanghai Tunnel Engineering Co.,Ltd.,Shanghai 200232,China;Department of Geotechnical Engineering,Tongji University,Shanghai,200092,China;Department of Civil and Environmental Engineering,Universitat Politècnica de Catalunya(UPC),Barcelona 08034,Spain;School of Engineering and Design,Technical University of Munich,Munich 80333,Germany)

机构地区：[1]上海隧道工程有限公司,上海200232 [2]同济大学土木工程学院地下建筑与工程系,上海200092 [3]加泰罗尼亚理工大学土木与环境工程学院,巴塞罗那08034 [4]慕尼黑工业大学工程与设计学院,慕尼黑80333

出　　处：《科学技术与工程》2024年第24期10439-10448,共10页Science Technology and Engineering

基　　金：国家重点研发计划(2019YFC0605105);国家自然科学基金(41877227);上海市科技创新行动计划(21DZ1201103)。

摘　　要：上海北横通道工程Ⅷ标段为15.5 m超大直径盾构隧道,区间在出洞后仅54 m即近距离侧穿内环高架,最小覆土埋深比为0.5,距离桥墩桩基最近仅3.9 m。施工过程中既有桩基、地层和盾构穿越表现出显著的相互作用影响。开展了盾构施工影响区范围内的地表沉降和桥墩桩基的位移监测,并基于实测结果对盾构开挖过程的三维精细化数值分析结果进行对比验证。结果表明:数值结果与实测数据吻合良好,均反映了在浅埋超大直径盾构出洞后即穿既有高架桥梁桩基下,在横断面上表现为地表中间沉降,两侧显著隆起的特点,其中部分隆起量在开挖完成后由于卸载恢复;侧穿高架过程中表现出显著的隧-土-桩相互作用:既有桩基对盾构开挖引起的地层变形存在钳制作用,导致沉降槽两侧表现为非对称隆起,地层变形同时也协同带动既有桩基的竖向隆起;在开挖的纵向响应上,沉降区间受到两侧工作井与桩基约束而扩展有限;侧穿引起桩身发生背向隧道最大值超过3 mm的水平侧向屈曲位移,同时在单桩中产生最大达到150 kN的附加轴力。SectionⅧof Shanghai Beiheng Passageway is a super large shield tunnel with a diameter of 15.5 m,which closely sidecrossed the inner circle viaduct after escaping from the shaft for only 54 m.The minimum covering soil burial depth ratio is 0.5 and the shortest distance between the tunnel and pile foundation of the viaduct is only 3.9 m.Obvious interaction between the existing pile foundation,stratum,and shield crossing is present.Comprehensive monitoring on the ground surface settlement and pile displacement within the influential zone of shield tunnelling was conducted.Based on the monitoring data,the results of a refined 3D numerical model were compared and verified.The results show that the numerical results match well with the measured data,which both reflect the characteristics of settlement in the middle and significant upheaval on the two sides of the ground above the tunnel axis.Partial upheaval will be recovered due to unloading after the excavation.There is a significant effect of tunnel-soil-pile interaction during the side-crossing of the viaduct.The existing piles have a clamping effect on the stratum displacement induced by shield excavation,which results in asymmetric ground upheaval on the two sides.In the meantime,the deformation of the stratum synergistically drives the uplift of the existing piles.On the longitudinal ground response due to excavation,restricted by the working shaft and pile foundations,the expansion of the settlement section is limited.The shields side-crossing causes the piles to deform laterally outwards for a maximum value of 3 mm,and induces additional axial forces in a single pile that exceeds 150 kN.

关 键 词：盾构隧道 桩基穿越 既有桥梁 自动化监测 地表沉降 桩土相互作用 

分 类 号：TU91[建筑科学—建筑理论]