Study On The Anti-surface Deformationperformance Of Composite Foundation Withopening Of Transmission Tower

As the energy strategy about coal for power transmission has been put forward in our country, there are a large number of transmission lines through mining subsidence area. The Surface subsidence in mining area will affect the transmission line safety. There are some protection measures related to the transmission tower structure. The composite foundation with opening that is good economical and environmental protection have been used in the project. But the research on the anti-surface deformation performance of composite foundation with opening of transmission tower hasn’t carried on. So it has an important significance to study the surface deformation resistance of the transmission tower with the composite foundation with opening.The large-scale equipment to simulate surface deformation of transmission tower was developed in this article. The typical 220 k V transmission tower was taken as the research object. The experiments about the combination action of transmission tower, ground and foundation(independent foundation and the composite foundation with opening) have been carried. Under influence of the surface deformation, the relationship between the structure members stress and the support displacement have been studied. The relationship between the stress of the composite foundation with opening and the surface displacement has been analyzed. Through comparing the deformation resistance performance of the transmission tower with independent foundation and composite foundation with opening, the composite foundation with opening is proved to be effective. At the same time, through comparing the result between the model test and numerical simulation, the results of numerical simulation are verified to be effective.The typical 220 k V transmission tower was taken as the research object. The finite element modeling is modeled by ANSYS. The single ground deformation(11 kinds typical conditions) and the composite surface deformation(6 kinds typical conditions) are analyzed. The influence rules about the damage form, members stress and deformation of the transmission tower are researched, meanwhile the limit displacements of the supports are got. Through the above work, we got the safety evaluation standard of the transmission tower in the mining area.The combined action finite element model of the typical 220 k V transmission tower, foundation and ground is established here. The anti-surface deformation performances of transmission tower with different foundations(independent foundation, composite foundation, composite foundation with opening) were researched. The change rule about the deformation of the top surface soil, the surface soil stress and the stress on the bottom of the foundation, the support displacement and the upper structure stress were studied in the typical surface deformation(tensile deformation, compression deformation, curvature deformation of positive and negative curvature deformation). The results show that the composite foundation and the composite foundation with opening have the great ability of anti-surface deformation performance compared to the independent foundation, and the anti-surface deformation performance of the composite foundation and the composite foundation with opening is basically similar.The deformation resistance optimization analysis was carried in this chapter. The influence of the plate thickness on the surface deformation resistance of the combination action of transmission tower, ground and foundation was studied. The results show that the plate thickness of the composite foundation with opening should be taken for 300~400mm, as well as about 1/30~1/20 of the tower root length. At the same time, through the study of the influence of the foundation soil on the surface deformation resistance of the composite foundation with opening, the results show that the protective effect will be weaker on the harder surface soil condition. When the towers are built on the harder surface soil condition, the plate thickness of the composite foundation with opening should be increased reasonably.