| As transmission line is the main channel for long-distance power transmission, line in operation requires safety and reliability. How to accurately predict the deformation of the mining area where the line passing through, what the surface deformation law will be in the future, how about the stability of the tower, what kind of measures should be taken to analysis and evaluation the transmission line scientifically, etc, these questions above are all urgent problems needed to be solved. This thesis, based on a typical engineering project, studied the time and space effect of surface deformation and its influence on the surface stability. The main contents are as follows:In this thesis, the RTK technology was used to beserve the surface deformation. And then the surface deformation is calculated by using the probability integral method and FLAC3 D respectively. The measured values, predicted values and simulated values are compared. And the results verify the rationality and feasibility of the prediction and simulation method.Taking the mining area which the typical 220 k V transmission line passing through as the background, the influence of mining process on surface deformation and the characteristics of surface deformation at different locations in mining area are studied, and the influence of ground deformation on the tower at different spatial locations in mining is analyzed. The influence laws of mining process and space characteristics of surface deformation in mining area on steel tower are obtained.In the process of mining, the soil arch will be formed by soil arch effect in the overlying layer. FLAC3 D is used to establish a computational analysis model of typical mining area and study the influence of soil arching effect on the surface deformation. The result shows that the existence of the soil arch effect can effectively reduce the maximum surface subsidence and the subsidence rate.By using the finite difference software, taking the Loess and sandstone in the typical soil layer as an example, the subsidence law of the ground surface is analyzed, and the relationship between the depth ratio and the ground surface subsidence is obtained. Analysis results show that with the decrease of the depth-thickness-ratio, the sinking value and the sinking rate increase gradually. In the case of depth-thicknessratio less than 30, the surface subsidence is significantly increased. On the whole, the surface subsidence and the subsidence rate are greatly influenced by the mining depth. Under the same conditions, the surface subsidence and the subsidence rate of sandstone are smaller than that of the loess.The concept of standard depth-thickness-ratio is put forward, and the standard calculation method of depth-thickness-tario is proposed. Analysis shows when the standard depth-thickness-ratio is greater than 1, the surface subsidence rate is small and it changes slowly; when the standard depth-thickness-ratio is less than or equal to 1, surface subsidence rate is large and it changes quickly. At the same time, the equivalent calculation method is proposed, and the equivalent depth-thickness-ratio is obtained, which is more detailed than the standard one. It is suggested that convert the depththickness-ratio to the depth-thickness-ratio of sandstone, when consideraing the technical measures for the transmission tower in the mining area. For sandstone, the surface deformation is serious when the equivalent depth-thickness-ratio is less than 30, and the surface deformation is slight when the equivalent depth-thickness-ratio is more than 100.The time function model of ground surface subsidence is established, and the time characteristics of the ground surface deformation are studied. The time function model can well reflect the actual physical process of the surface subsidence. Several design proposals for the transmission line in the mining area with different equivalent depththickness-ratio are presented. |
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