| Along with our country highway construction gradually toward the " long, large,deep," the direction of development, the instability of the surrounding rock damagecaused by the disaster forecast to become one of the major tasks facing the. But becauseof the unique characteristics of highway tunnel project, the existing tunnel safetycriterion theory and method is not mature, and not applicable to special highway tunnelstability standard of judgment and method.This article based on Guangdong provincetraffic hall" science and technology project for large span flat tunnel excavationconstruction safety and project decision of key technology", through a combination ofcollecting spot measurement, numerical simulation analysis and mathematical statisticsanalysis and other means of three lane road tunnel safety judgment method wasstudied.Thesis of three lane highway tunnel field monitoring measurement data and theresults of numerical calculation and data statistical analysis, a comprehensive analysisof the large span flat tunnel four kinds of commonly used methods of ultimatedisplacement, including: three step seven step excavation method, next door, in themethod of center cross diaphragm method and Twin-Side heading method. Firstly,through the influence of surrounding rock stability of elastic modulus, Poisson’s ratio pE, internal friction angle, cohesion C for four parameters of the random combination ofthe numerical simulation, reach four kinds of methods each excavation segment limitdisplacement and ultimate displacement. The strength reduction method is introduced,through the internal friction angle, cohesion for C using the same safety coefficient ofreduction, the overall limit displacement of highway tunnel. A combination of severalmethods of portfolio analysis, to establish a set of suitable for the tunnel constructionsite safety reference value system, and in the future the practical engineering applicationof continuous improvement.The main contents of this paper are:（1） in combination with the characteristics of highway tunnel by field test, astatistical analysis of three lane road tunnel measured data, to develop a set of highwaytunnel limit displacement.（2） through to four kind of large span highway tunnel numerical simulationmethod and the results were statistically analyzed, obtained in different surroundingrock grade, different buried depth of four kinds of method of ultimate displacement oftunnel excavation and the whole displacement. （3） the strength reduction method is introduced into the tunnel safety referencevalue obtained from the simulation study, four kinds of methods of safety coefficient,that based on the strength reduction of three lane road tunnel limit displacement.(4)through the results of the three methods is analysed, reach four kinds of method ofultimate displacement, and to develop a set of three lane road tunnel safety referencevalue. |
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