Second lining of tunnel cracks is one of the most frequent diseases in the highway tunnel construction, which adversely impacts the project quality as well as traffic safety.

隧道二衬开裂是目前隧道工程中经常出现的病害，严重影响工程质量和交通安全。

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The calculation of structural load on the lining of tunnel with shallow overburden shows that the load on composite lining will be shared by primary support and secondary lining.

隧道衬砌在浅埋段的结构荷载计算表明，复合式衬砌中的初期支护和二次衬砌一般要共同承担荷载。

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These findings, backed up by other data collected from conventional inspections, led London Underground to investigate the replacement of the tunnel lining.

这些发现，是从常规检查而收集出来的其它数据中被证实，引致伦敦地下铁要调查研究隧洞衬砌的替代物。

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The Rail Accident Investigation Branch (RAIB) said the broken sections were part of an auger drill that had "penetrated the tunnel lining before falling on to the track".

BBC: Construction drill came from site above rail tunnel