长距离共线基坑下卧隧道上浮控制措施及效果研究

Control Measures and Corresponding Effectiveness for Tunnel Heave Induced by Long Collinear Overlying Excavation

上方基坑开挖引起下卧隧道上方土体卸载,易诱发隧道上浮,影响结构正常服役。依托深圳桂庙路快速化改造工程,针对不同区段基坑开挖期间下卧隧道上浮,提出差异化的变形控制措施,并通过实测数据验证措施的有效性。结果表明:距基坑中心越近,下卧隧道上浮量及土体卸载率越大;当开挖区域距离隧道大于30 m时,土体开挖卸载对隧道变形基本无影响。对不同区段针对性地采取了“纵向分段分步+竖向分层+左右分幅”、“纵向分段分步+竖向分层+左右分幅+旋喷桩加固”,以及“竖井跳挖+抗隆起框架”3种差异化控制措施。实测数据表明:土体最大卸载率为0.52,隧道最大上浮量为13.4 mm,表明隧道变形控制效果较好。本研究可为类似长距离共线基坑下卧隧道工程提供重要参考。

Overlying excavation causes stress relief in the soil above an underlying tunnel,which easily induces tunnel heave and affects the serviceability of the tunnel.Based on the reconstruction project of Guimiao Road in Shenzhen,this paper proposes differential countermeasures for the underlying tunnel heave subjected to overlying excavation in different sections and verifies the effectiveness of the measures via field measurements.The results showed that as the distance to the excavation center decreases,the heave of the underlying tunnel and the unloading rate of the soil increase.When the excavation area is more than 30 m away from the tunnel,the excavation-induced soil stress relief does not significantly affect the tunnel deformation.In various excavation areas,longitudinal segmentation+vertical stratification+separate excavation for left and right side;longitudinal segmentation+vertical stratification+separate excavation for left and right side+reinforcement of high-pressure jetting piles,and spaced shaft excavation+anti-heave frame were adopted.Furthermore,the measured data showed that the maximum unloading rate of soil mass was 0.52,and the maximum uplift of the tunnel was 13.4 mm.This indicated that the effectiveness of these measures was generally satisfactory.This study offers valuable insights into similar projects.