| The studies of deformation and stability become an important issue on the highwaytunnel excavation, when Rapid development China’s western transport has rapid developmentwith the steady implementation of western development and the Wenchuan reconstruction.Currently, many scholars and experts from home and abroad who have done a lot of researchhave yielded some results by theoretical analysis, model tests, field tests, numericalsimulation and other means. However, the research work on the tunnel stability still requiresin-depth due to the uncertainty and complexity.In this paper, the mainly research works based on Maerkang tunnel project are made asthe following aspects:The current Situations about deformation monitoring measurement and stabilityevaluation in highway tunnel surrounding rock, this article conducted a systematic summaryand analysis, and analyzed the failure factors influencing the Stability and evaluation methodsof surrounding rock.The Maerkang tunnel’s project overview (Geographical conditions, lithology, geologicalstructure and seismic safety evaluation, hydrogeological conditions and adverse geologicalphenomena), site construction methods and technological process were discussed, accordingto the failure mechanism and factors of tunnel surrounding in field the actual, the factorswhich affects stability of Maerkang tunnel surrounding rock were analyzed. The researchshows that the surrounding rock of Maerkang tunnel is mainly grade of Ⅲ. In the actualconstruction process, Because of the presence of weak structural plane, leading to theexpansion of the surrounding rock loose circle, affecting the stability of surrounding rock. Inthe actual construction process, the monitoring of this surrounding rock section should bestrengthened. When the information is feedbacked timely, for reducing the harmfuldeformation and ensuring the overall stability of the surrounding rock, the support parametersof the surrounding rock will be regulated and the method of construction workers or supportform will be changed.Author obtain the regression curve of a variety of the surrounding rock conditions afterthe monitoring data of the tunnel is analyzed that use the various function, and authordetermine the hyperbolic function and logarithmic function to predict the ultimatedeformation amount of the Maerkang tunnel crown settlement and the level of convergence,to determine the supporting effect of surrounding rock in the construction process. Finally,compared with the accuracy of a variety regression function, proposed the choose ofregression curve basing on different monitoring content and method to choose a differentfunction to return fitting.Maerkang tunnel was simulated using finite element analysis, the stress-strain trendsduring tunnel excavation was analyzed in detail, contrast validation and field data to judge the final steady state of surrounding rock, Provide a reference for initial support design andconstruction of the tunnel. The research shows that the surrounding rock have plastic failureregion of different degrees in the supporting conditions. Tension damage to the main vault andbase plate are mainly in the arch waist and foot of a wall are the shear destruction. Under theconditions of support, the surrounding rock appears different degrees of plastic failure region.The breakage that happen at the vault and base plate is mainly tension destruction, and thebreakage that happen at the arch waist and the Corner is mainly shear destruction, in order toensure the stability of surrounding rock should strengthen support in these parts. The resultsalso show the excavation in the construction process of Maerkang tunnel that the surroundingrock of the grade of Ⅲ uses full-face method to excavate and the surrounding rock of thegrade of Ⅳ uses up-and-down-stairs law to excavate is more reasonable. These works haveguiding significance for Tunnel design and construction.The conclusions of this paper have the reference value for the construction of similartunnel. |
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