| The construction of tunnels in mountain city can overcome terrain conditions, conducive to the development of urban transport, but the city of tunnel entrance are generally shallow zone, the hole cover layer is relatively thin, and there are the soil surrounding rock crushing, even for miscellaneous fill soil surface. Under such wall rock conditions the presence of great section of tunnel entrance with small spacing following questions:temporary slope and elevation slope instability easily damaged, cannot rely on their own stability of surrounding rock into arches and reinforcement measures of selectionView of the above problem, this paper relies on Jinan Shi Fang Yu tunnel project, the main research work are the following:(1) Factors affecting the stability and the failure mode of the slope of the hole, summary slope treatment of programs for slope failure in the form; The use of rigid limit equilibrium method for calculating safety factor of slope varies with soil mechanics parameters change the situation, by analyzing calculation results, Considered to ensure that the temporary tunnel entrance grew slope stability, Geotechnical investigation must be encrypted point.(2) According to Shi Fang Yu tunnel engineering geological features and construction difficulties, analysis Shi Fang Yu slope, upward slope hazards and disease control:The tall slope reinforcement measures of the hole, and the analysis of slope stability during excavation in real time; upward slope for cracking diseases, analyze the causes of the disease upward slope, and then propose appropriate action against cracking diseases.(3) Finite element MIDAS GTS simulation study with small clear distance tunnel door and three steps of seven steps excavation method of settlement of displacement and plastic zone size, choose suitable for urban shallow buried tunnel into the hole excavation construction methods, and according to the working condition of simulated choose reinforcement scheme.(4) By monitoring and measuring the stonework valley of the tunnel, get change information in the construction process of surrounding rock and support system; analysis portal section monitoring measurement data to determine the tunnel excavation process stonework valley periods need to focus on monitoring and timely feedback analysis.Currently Shi Fang Yu tunnel project has been completed, about Shi Fang Yu tunnel construction methods and reinforcement measures proposed are reasonable, the project has achieved remarkable results. |
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