Study On Stress And Optimization Design Of Secondary Linings In Highway Tunnel

In order to study on stress and optimization design of secondary linings in highwaytunnel,the project located in based on the Baojiashan highway tunnel,Mingyazi highwaytunnel,Liujiaping tunnel group.Through the in-situ monitoring measurement method,studiedon shared proportion of surrounding rock pressure to secondary linings of rock tunnel andloess tunnel;through the finite element numerical simulation method,studied on safety andstructure optimization to secondary linings.The main research contents and results are asfollows：(1)Through the in-situ monitoring measurement method,obtained that IV-class,Ⅴ-classof deep-buried rock tunnel shared proportion of surrounding rock are26.3%and38.2%;IV-class,deep-buried,Ⅴ-class,Ⅵ-class shallow-buried loess tunnel shared proportionof surrounding rockt are39.9%,43.5%and48.8%.(2)Through the finite element numerical simulation method,obtained that vault,archlumbar,foundation,inverted arch side wall side and invert the central are the mostdisadvantageous position of the force to secondary linings;analysis of side pressurecoefficient change on influence to stress,deformation,safety coefficient; Combined with thedesign specification,obtained that IV-class,V-class of deep-buried rock tunnel and IV-classdeep-buried loess tunnel most adverse side pressure coefficient are0.15,0.30and0.15.(3Analysis the relationship that between the strength grade of and durability ofsecondary linings—low strength concrete is negative to durability of secondarylinings;combined with our country design situation of highway tunnel,put forward to use C30concrete instead of C25concrete, to improve the secondary linings durability,prolonging themaintenance cycle and service life of the tunnel.(4)In C30concrete instead of C25concrete conditions,study on secondary liningthickness effect on structure safety,with increasing thickness of secondary lining,thevault,arch lumbar,foundation,inverted arch side wall side safety coefficient nonlineartrend,and invert the central safety coefficient linear trend growth;the rocktunnel(IV-class,Ⅴ-class deep-buried),loess tunnel(IV-class deep-buried,Ⅴ-class,Ⅵ-classshallow-buried)the minimum safe thickness of secondary lining are given...