盾尾挤压作用下盾构管片施工期力学行为研究

Study on Mechanical Behavior of Segment under Shield Tail Extrusion during Shield Tunnel Construction

为研究施工过程中盾构管片在盾尾挤压作用下的力学行为,以成都地铁18号线为工程背景,基于混凝土塑性损伤理论,建立了考虑土压力、注浆压力、千斤顶推力等施工荷载的拼装式管片数值模型,模拟分析了管片拼装完成、盾壳移动、千斤顶回缩施工循环过程中的衬砌结构位移、应力与损伤规律。结果表明:在地层荷载、盾尾挤压和千斤顶力综合作用下,施工过程中管片位移和应力不断发生变化,当盾壳向右偏离隧道轴线1°时,盾尾挤压会导致接缝错台以及管片出现损伤,且错台主要出现在环向接缝处,损伤以拉伸损伤为主。

In order to study the mechanical behavior of segment under the action of the shield tail during the construction of shield tunnel,taking Chengdu Metro Line 18 as a subject for study,and considering the construction loads such as earth pressure,grouting pressure and jack thrust,a numerical model of erected segmental lining was established based on the concrete plastic damage theory.The mechanical behavior of the lining structure during the completion of segmental lining,the movement of shield shell,and the jack retraction was simulated,including the displacement,stress and damage of segment.The results show that under the combined action of formation load,shield tail extrusion and the jack force,the displacement and stress of the segment will vary continuously during the construction process.When the shield shell deviates from the tunnel axis by 1°to the right,the extrusion of the shield tail will cause the joint dislocation and the segment damage,and the dislocation mainly appears in the circumferential joint.Besides,the damage is mainly caused by tensile damage.