Study on overhanging deformation of high arch dam during construction period before and after treatment of complex geological conditions
[Objective]The site of high arch dam usually faces complicated geological conditions,including deep unloading zone,joint,crack and so on.Deep joint is a special geological defect caused by the unloading rupture of deep rock mass.The stress distribution and deformation of high arch dam are induced under the comprehensive influence of the factors such as dead weight,temperature and concrete creep,and further increase the overhanging deformation during the construction period is not conducive to the working state of high arch dam,thus affecting its stability and safety.[Methods]This paper adopts the feedback simulation analysis method of the whole process of the dam,and takes a dam under construction in southwest China as an example to estab-lish a detailed model of the dam under complex geological conditions.According to the overall concrete pouring and arch sealing grouting plan of the dam body,the simulation and analysis of the construction of the whole dam section are carried out to compre-hensively reflect the temperature field,stress field and deformation during the construction period.The influence of geological de-fects including grade Ⅱ structural plane,grade Ⅲ structural plane and foundation surface replacement block on overhanging de-formation and dam working behavior is studied.[Results]The result show that the overhang degree of high arch dam increases with the increase of pouring height from the dam foundation,and the overhang deformation value below 1/3 dam height is small.The overhanging deformation tends to flow upstream from 1/3 to 2/3 of the dam height,and the overhanging deformation disap-pears above 2/3 of the dam height,Resulting in the deformation in the downstream direction.The simulation result of the whole dam show that the maximum value of overhanging deformation in upstream direction is about 20.000 mm,which occurs between 1/3 dam height and 2/3 dam height.The maximum downstream deformation is about 13.000 mm and occurs above 2/3 of the dam height.Under the same elevation,the deformation fluctuation from upstream surface to downstream surface is affected by temperature load,creep and other comprehensive factors,and the influence of this error on overhanging deformation monitoring should be considered in the actual installation layout.The displacement block of grade Ⅲ structural plane and foundation surface has little influence on the deformation during the construction period of the arch girder dam section.The Grade Ⅱ structural plane(F2,F2-1 faults)is located below the 14# dam section,which has a great influence on the overhanging deformation and the downstream deformation of the dam roof during the construction period.The maximum overhanging deformation increase is about 4.000 mm,and the downstream deformation increase of the dam roof is about 7.500 mm.[Conclusion]According to the calcu-lated result,the mechanical parameters of the dam body and the elastic modulus and mechanical parameters of the second-order structural plane should be considered in the inversion of deformation data during the construction period.
high arch damgeological defectssimulation calculation of the entire dam processoverhanging deformationcon-struction perioddeformation
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