| The geological conditions of the main powerhouse on the left bank of Wudongde hydropower station on Jinsha river are extremely complicated,The main powerhouse excavation scale is large,the maximum height is 89.80 m,and the maximum span is 333.0m,mainly for the gate hole type.The excavation of main powerhouse has the characteristics of large span and high side wall.During the excavation of the main powerhouse,a series of geological phenomena,which are not conducive to the stability of the surrounding rock,are caused by the unloading of surrounding rock which will seriously affect the stability of the surrounding rock and the engineering effect of the main powerhouse.Therefore,This paper analyzes the engineering geological data of the surrounding rock of the underground powerhouse on the left bank of Wudongde Hydropower Station,and classifies the surrounding rock.Combined with the relevant research data of the underground powerhouse,the appropriate numerical analysis method is adopted,and the effective analysis software is used to establish the research area of the left bank main plant.The 3D geological model is combined with the deformation monitoring data during the excavation of the main building to analyze the deformation characteristics of the main building on the left bank of Wudongde,and qualitatively analyze the surrounding rock stability of the main building.based on geological analysis and deformation analysis,numerical simulation The step-by-step excavation process of the main building is reproduced,and the variation characteristics of the basic field such as the displacement field,the stress field and the plastic zone during the excavation process of the main building are obtained,and the deformation characteristics of the main building excavation process and the stability of the surrounding rock are quantitatively analyzed.On the basis of numerical analysis,combined with the main plant support measures,the main plant excavation and support process was simulated,and the simulation calculation results before and after the main plant support were compared and analyzed,and the main plant support effect on the left bank was analyzed.Finally,based on the above analysis,the comprehensive stability evaluation of the left bank main building is carried out.The main research contents are as follows:1)According to the characteristics of Wudongde underground powerhouse project in China,the background and significance of this paper are selected.The research status of the typical Three Gorges Hydropower Station,Xiluodu Hydropower Station and Shuibuya Hydropower Station and the research status of underground powerhouses are reviewed.To lay the foundation for the research of this paper;systematically expound the research method of surrounding rock stability,and combine the characteristics of Wudongde underground powerhouse project to select the appropriate research method.2)The main research is to find out the basic geological conditions of the main plant on the left bank,and lay a solid geological foundation for the next research content.Through the petrophysical mechanics experiment,the recommended values of the physical and mechanical parameters of the surrounding rock of the main building are provided.3)Summarizing the influencing factors affecting the stability of the surrounding rock of the main building on the left bank,mainly including geostress,geological structure,rock mass structure,karst,groundwater,etc.This chapter mainly analyzes the above influencing factors to stabilize the surrounding rock of the main building.The influence process and mechanism,qualitative evaluation of the surrounding rock stability of the main plant in the left bank;summarizing the domestic peripheral rock classification methods and standards,combined with the characteristics of the surrounding rock of the main building on the left bank of this paper,selecting the surrounding rock classification method of the water conservancy and hydropower project to carry out the surrounding rock of the main building Grading.4)According to the geological phenomena exposed in the excavation process of the main building,such as slow dip cracks,small caves,structural structural planes,etc.,the deformation and failure modes of the cavern are predicted;combined with the multi-point displacement gauge embedded in the main building The displacement data of the monitoring is used to analyze the displacement characteristics of the main building during the excavation and support process.5)Using the flac-3D software to numerically analyze the geological model,first simulate the initial geostress field of the dam before the excavation of the main building,and simulate the reproduction of the main building on the basis of the initial geostress field.The displacement field,stress field,plastic zone,etc.during the excavation process are analyzed and evaluated by analyzing the basic fields such as displacement field,stress field and plastic zone during the excavation process of the main building.6)Combined with the main plant support scheme,the surrounding rock stability after the support of the main plant on the left bank is simulated.The simulation results of stress field,displacement field and plastic zone under two different working conditions before and after support are compared and analyzed.The effect of the main plant support on the left bank and the influence of support on the stability of surrounding rock are analyzed.The content of surrounding rock stability evaluation mainly includes the classification and distribution law of surrounding rock,the type and distribution of unfavorable stable geological phenomena of surrounding rock,the distribution of surrounding rock stress meter,the displacement characteristics of surrounding rock deformation,and the surrounding rock support effect.Comprehensive evaluation of the stability of the surrounding rock of the main plant. |
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