| Futang power station is located in the Minjiang River segment of Wenchuan Country of Sichuan Province. The power station is diversion type power station of low gate dam with a normal storage level of 1268.0 m, a highest gate dam level of 31 meters and a reservoir capacity of 2,974,000 cubic meters, the length of diversion tunnel of which is 19.57 kilometers, installed capacity is 360MWFutang power station is constructed on the basis of deep and thick overburden, the foundation of which mainly consist of five overburdens which, in general, belong to multiple, complex foundation. The foundation are formed by the inter-layer of fine and crude earth, in the different level of the layer, are distributed lenticular sand, which result in the poor uniformity. The power station is situated in the area of 8° earthquake fortified zone, the fourth sand layer are probably liquefied and the second sand layer are not liquefied in the situation of 7°, 8° earthquake. However the security index of anti-liquefying of second sand is not very high in the situation of 8° earthquake.In this paper, by focusing on the treatment of gate dam foundation of Futang power station under construction, and finally by the researches, contemplation and exploration made on the basic treatment of deep and thick overburden, we intent to use these results to offer some reference for the related projects.Our researches are focused on the basic treatment as anti-seepage style and related problems, as regards the anti-seepage measures ofgate dam foundation, the combination measures of vertical anti-seepage and horizontal blanket anti- seepage are studied here. Concrete anti-seepage wall are penetrated through the alluvial layer with high water permeability and put in the relative impermeable layer. In order to chose the reasonable structure and size and determine the execution progress and order, it is necessary to first calculate the architecture and then analyze the deformation of foundation. According to these calculation results, proper measures are chosen to secure the proper operation of sluice.According to the structure layout of Futang power station design, geological parameters and calculation results of seepage, the stability and stress of gate chamber and retaining dam are calculated, the security index and stress of anti-slide can can meet the requirement of criterion.The structure of dam and foundation was analyzed in terms of 3-dimentional finite element static analysis and kinetic reaction analysis by ANSYS software. static analysis was analogued by elasticity and ideally elastic-plasticity material, while kinetic analysis was carried out by the combination of modal analysis and kinetic reaction analysis hierarchical method. By analyzing and calculating the structure and stress distribution status of foundation under time of completion, operating period and earthquake condition, the initial determination on the kinetic strength and liquefied possibility of underlying sand layer beneath the dam foundation are obtained.On the basis of comparison of different plan, calculation results of seepage of dam foundation and the calculation results of gate dam foundation settlement value and the integrated analysis of the calculation results of load supporting capacity, with additional reference to other project, the resolutions to the anti-seepage,anti-liquefaction and uneven sedimentation of foundation were put forward. The basic uneven settlement problem were controlled well, also the anti-liquefied problem of sand layer nearly was solved in this plan. When increasing the basic gravity after the project completion, the proportional lowering of seepage damage of sand in overburden foundation are greatly improved. which avoid the damage to the seepage of interlayer and inner layer of foundation, which is surpass the suggested standard, therefore the meet the seepage stability of overburden foundation can meet the requirement.
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