裂缝长度对盾构隧道管片结构破坏模式模型试验研究

Model test study on failure mode of segment structure of shield tunnel with crack length

依托国内某地铁区间盾构隧道工程,采用相似模型试验的方法,通过对盾构隧道管片的声发射数据、管片衬砌位移及破坏过程素描等数据的分析,研究不同裂缝长度条件下管片衬砌在外荷载作用下的力学响应及其承载性能。研究结果表明:裂缝的存在降低了结构整体刚度,裂缝长度对管片衬砌结构的力学特性具有显著影响,1/3幅宽是裂缝长度对管片衬砌结构力学性能影响的分界点;当裂缝长度大于1/3幅宽时,随裂缝长度增加,相同荷载条件下管片椭圆扁平率急剧增大,结构的极限承载力逐渐降低,结构的失稳破坏趋于突发性破坏。

Based on a domestic metro shield tunnel section project,this paper studies the mechanical response and bearing capacity of lining segments with different crack length under external loads by conducting a series of model tests and analyzing acoustic emission data,values of displacement and failure process sketch of lining segments.The results indicate that the existence of cracks reduces the overall stiffness of structure.The length of cracks has a significant impact on the mechanical properties of lining segments.The turning point for the influence of the crack length on the mechanical properties of the lining structure occurs at the 1/3 of the segment width.If the crack length is greater than 1/3 of the segment width,with the increase of the crack length,the elliptical flattening rate of the segment gains sharply under the same load.This phenomenon results in the gradual decline of the ultimate bearing capacity and the increase of the chances of sudden failure.