Reason for Cracks of Double-arch Tunnel without Middle Drift and Analysis of Mechanical Characteristic
Research purposes:To reveal the reason for invert lining cracking in double-arch tunnels adopting the construction technology without middle drift,this paper first obtained the force patterns of the first tunnel by field monitoring.Based on the mechanism characteristics,this study put forward a load-structure calculation model for the first tunnel considering the excavation of the second tunnel.The results of numerical simulations combined with field monitoring were utilized to analyze the causes of the invert lining cracking.Finally,the safety of the secondary lining was evaluated and the corresponding control measures were suggested.Research conclusions:(1)Before the excavation of the second tunnel,the secondary lining of the first tunnel is in a symmetrical stress state and the safety factor of each section is greater than 2.4.After the excavation of the second tunnel,the first tunnel is under an unsymmetrical stress state,and the safety factor of the right side of invert is only 1.25.The inner surface of the right side of invert is exactly where the maximum tensile stress is located,which is consistent with the actual position of observed cracking.(2)The cracks of invert lining in the first tunnel is caused by uneven settlement and unsymmetrical pressure due to the excavation of the second tunnel.(3)Enhancing the support resistance factor could improve the safety of the lining structure,but the safety factor has little change when the support resistance factor is higher than a certain value.(4)The research results can provide guidance for the design and construction of similar double-arch tunnels.
construction without middle driftcause of crackingnumerical analysisdouble-arch tunnelsafety evaluation
万方数据
维普
