盾构隧道施工阶段管片上浮的力学分析

 盾构隧道衬砌管片在施工阶段处于复杂的受力状态，易出现管片错台、整体上浮等现象。对盾构隧道施工阶段管片注浆段进行受力分析，考虑静态上浮力和动态上浮力，分别分析其作用机制，提出上浮阶段的衬砌环受力模型及计算公式。针对盾构隧道衬砌环在正常设计状态与上浮状态下的受力不同，采用修正惯用法衬砌设计理论分别对其进行内力计算，并将计算结果进行对比分析。结果表明：上浮状态下管片的弯矩值、剪力值和轴力值分别比正常设计状态下的管片内力增加64%，51%和46%，表明隧道上浮对管片受力不利。其中施工阶段动态上浮力对管片的受力影响非常大，超过静态上浮力，必须对其进行合理控制，防止压裂管片。

MECHANICAL ANALYSIS OF SEGMENT FLOATING DURING SHIELD TUNNEL CONSTRUCTION

The lining segment is in a complex stress state during shield tunnel construction,which is prone to go dislocation and have wholly rising displacement.Based on the analysis of segment in grouting section and considering static buoyancy and dynamic buoyancy,the buoyancy is respectively analyzed during shield tunnel construction.The mechanical model for segment ring in floating phase and calculation formula are presented,respectively.Aiming at the difference of segment ring between normal design state and floating state,the modified routine method is carried out to calculate lining internal force to draw a comparison.The results show that,comparing with segment ring in the normal design state,the bending moment,shear force and axial force values of segment increase by 60%,51% and 46% in floating state,which indicates that segment floating is adverse to its safety.The stress of segment is affected by dynamic buoyancy greatly during construction stage,which is larger than static buoyancy and must controlled reasonably for preventing the segment fracture.