Study on Evaluation Method of Structural Safety Factor Considering Insufficient Thickness of Tunnel Lining
In order to improve the accuracy of underthickness safety evaluation of tunnel lining structure and to measure the safety factor of tunnel lining structure accurately,the change law of structure safety factor is studied when underthickness diseases occur in different degrees and ranges at the arch,waist and foot of the lining,based on the calculation method and numerical simulation results of tunnel lining structure safety factor.Assuming the principle of volumetric strength equivalence,the influencing factors of underthickness of each lining structure were quantified,the underthickness position influence coefficient μ,scale influence coefficient λ and degree correction coefficient ψ were introduced,and the optimized underthickness safety coefficient correction formula of lining structure was constructed based on calculation examples.The results show that:1)When the lining thickness is insufficient,the safety factor of the disease area decreases obviously,and the safety factor of other parts does not change basically.2)With the increase of underthickness depth and scope of the lining structure,the safety coefficient of each typical part of the lining shows a decreasing trend,in which the arch top has the largest decline,the waist is the second,and the arch foot is the least,but the arch foot is the most vulnerable to the influence and decreases to the standard requirements.3)The underthickness depth of the lining structure has a larger influence on the safety factor than the underthickness range of the lining structure.
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