传力垫片对管片后端开裂影响的数值模拟研究

Numerical Simulation on the Segment Cracking Induced by Backend Gasket

盾构施工期间的管片裂缝对衬砌结构的安全性及耐久性影响较大。结合福州地铁某区间隧道衬砌管片开裂的现场调查,在MIDAS数值平台上设计了均压、偏压推进2种工况,对衬砌管片的受力状态进行精细化三维数值模拟。重点关注管片中拉应力分布情况,分析当垫片分布不均匀或垫片脱空等不利因素存在时,管片后端裂缝的分布模式。当均压顶推且垫片失效时,管片仍处于安全状态;偏压顶推时,后端裂缝发展的危险区域均出现在垫片失效区域。

Segment cracks during the shielded tunnel excavation have a large impact on the safety and durability of the lining structure.Based on the field investigation for the segment cracking in shielded tunnel excavation of Fuzhou Metro,the numerical simulations for shielded even/eccentric jacking conditions are carried out by using the MIDAS platform.The distribution of the tensile stress with the segment and the segment backend cracking are well analyzed under the unfavorable conditions such as the uneven distribution or the voiding of backend gaskets.Under the even jacking condition,the segment remains in safety even with some unfavorable condition of gasket.Under the eccentric jacking condition,the segment cracking may occur on the backend area where lacking gaskets.