Study On Span-Ratio And Construction Method Optimization Of Road Tunnel With Super-Large Cross-Section

For single-hole four-lane super-large cross-section road tunnel, the current road tunneldesign and construction technology codes all aren’t specifically involved. Therefore, it isimportant to carry on the overall research on the design and construction of single-holefour-lane super-large cross-section road tunnel. Aimed at optimizati on problem of single-holefour-lane super-large cross-section road tunnel span-ratio and construction method, the articlemakes the following researches:(1)Based on the finite element numerical simulation method and AHP which ismuti-objective optimization, when tunnel span-ratioes are optimized, every index factor’svalue isn’t obtained, then,Analytic Hierarchy Process(AHP) method is employed, and thetunnel economy index is taked accout of, the different span-ratioes are optimized under Ⅰ～Ⅴ rank surrounding rock, finally,the rational span-ratioes of Ⅰ～Ⅴ rank surrounding rockare obtained.(2) Combined with the best span-ratioes of super-large cross-section tunnel under Ⅰ～Ⅴ rank surrounding rock, the different construction methods which are employed bysingle-hole four-lane super-large cross-section road tunnel are analyzed by using numericalsimulation, the forces of super-large cross-section tunnel are obtained,when tunnel isexcavated by different construction methods. The three indexes which include the tunnelforces, cost of per meter tunnel and construction time of per meter tunnel are considered, theconstruction methods which are employed by super-large cross-section tunnel construction areoptimized by using Entropy Method under Ⅰ～Ⅴ rank surrounding rock,finally thereasonable construction methodes which are employed by super-large cross-section tunnelconstruction under Ⅰ～Ⅴ rank surrounding rock are obtained, the reference is also providedfor super-large cross-section tunnel construction scheme selection in future.