| According to the newly built tunnel of Wenchuan to Maerkang based on engineering. In order to solve the difficult point and key technical problems of plateau alpine deep soft rock tunnel after the earthquake, we research on tunnel design and construction technology. Based on the monitoring and analysis of atmospheric temperature, formation temperature and surrounding rock stress to master character of surrounding rock, deformable features, temperature and stress characters of plateau alpine deep soft rock tunnel. According to the data on plateau alpine deep soft rock tunnel after the earthquake theoretical analysis and numerical calculation, establish of field coupling model of seepage and stress, and field coupling model of seepage, stress, and temperature. Focus on the tunnel characteristic of surrounding rock, deformation temperature stress research under the influence of temperature, stress, and groundwater conditions. Through the research provide theoretical basis for plateau alpine deep soft rock tunnel freezing injury prevention design.The main conclusions are as follows:1. Through the monitoring of tunnel longitudinal atmospheric temperature, study longitudinal temperature of tunnel change rule, where the temperature change and the outside air temperature change trends are basically identical, which presents the temperature in tunnel and outside tunnel the same change trend. While tunnel temperature sensitive degree decreases with the tunnel longitudinal depth. Freezing point of Zhe Gu tunnel appeared in about 100m from the entrance of the cave, the freezing phenomenon of the lining appeared in about 100 meters from the entrance of the cave.2. Based on the radial temperature of surrounding rock of tunnel monitoring, it is show that the overall temperature of surrounding rock will change with the change of seasons, and the more close to the airport the more intense to the surrounding temperature change, while the more far away from the airport the lesser intense to the surrounding temperature change.3 Due to surrounding rock lithology changes tunnel vault vertical displacement change will have different degree, when the tunnel across the inhomogeneous formation. The full surrounding rock displacement is small, while the broken surrounding rock displacement is big.4. According to the lining monitoring data, lining deformation is impacted greatly by disturbance of surrounding rock. Time effect and space effect influence each other. Timely and rational support, closed cavity has a positive influence on tunnel stability; Tunnel deformation depends on the control of the construction technology. If the construction technology is not up to the standard, it will affect tunnel deformation condition.5 By using finite difference software to simulate the tunnel buried deep section stress field single field calculation and stress field, seepage field coupling numerical simulation to analysis and comparison tunnels during the excavation of the main structure under the action of groundwater. By comparing single field simulation calculation and stress field and seepage field coupling to simulate calculation, it is show that displacement of the tunnel vault and arch shoulders are less than two field coupling displacement of the tunnel vault and arch shoulders. The influence of seepage field on stress field exists, especially in deep depth, high groundwater head mountain tunnel.6. Due to heat exchange of surrounding rock and atmospheric environment only can be done within a certain range. There is almost no heat exchange inside of surrounding rock and atmospheric environment, which lead the temperature of surrounding rock relatively stable. The influence of the temperature field on the tunnel excavation process is very limited. So the influence of the temperature field on stress field of tunnel excavation can be almost negligible. It can be thought of tunnel deformation only related to the seepage field and stress field, when the tunnel is excavating. With the operation of the tunnel the freeze-thaw cycle will affects tunnel, which will lead to deformation of tunnel. And as the longer operating time, the greater the deformation of surrounding rock of tunnel is studied. The frozen soil of tunnel portal section frozen-heave force will produce certain effect of lining. Frozen-heave force influence the mechanical behavior of lining and increases the deformation of surrounding rock and lining. According to the simulation frozen scope of surrounding tunnel porta is about 1.4 meters every year(Including thickness of primary support and secondary lining), which fit good with geological exploration data. Geological exploration data prove the reliability of the results of numerical simulation. |
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