| Based on the tunnel engineering of Chongqing mass transit line 1.using the methods of theory analysis,numerical simulation,the actual construction site verification,and so on,this paper aims at the mechanism and controlling of the stratum displacement caused by the large-span and small interval tunnel constructed in the intensely weathered granite with abundant water in southeast coastal areas of China, which is seldom reported in literature of domestic and foreign.It not only successfully directed the construction,but also can be applied in the following project.Through a comprehensive technology research,acquired research results are as follow:Firstly,compared with normal long span tunnel,the enlarging of the existing air defense tunnel have the following basic mechanical characteristics;â‘ The existing air defense tunnel can release stress in advans;â‘¡The first step of enlarging the existing air defense tunnel is the most dramatic changing of the rock stress.â‘¢Own to becoming long span cavern,stress redistribution after excavating becomes very harmful,and powerful support structure is needed to control its deformation.Secondly,study on three different excavtion modes which are centeral excavation and surppot first method,the central excavation and surppot after method,CD method, comparative analysis these aspects which are rock stress,displaces,surppot stress and the structure tilt rate,then we found the central excavation and surppot after method is the best.And,test and verify the correct of analysis by site monitoring.Thirdly,reachs conclusion of blasting parameter of the tunnel engineering of Chongqing mass transit line 1 by field test,site measuration,continuously feedback and adjust blasting parameter.These results arehopeful to have more benefit anddevelopment in allied engineering aftertime... |
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