Design Of RCC Gravity Dams And Section Optimization Of Nan’ao River Hydropower Station

Casting technology of Roller compacted concrete dam got rapid development in the world because of its rapid construction, short construction period and low cost.But the roller compacted concrete gravity dam is mass concrete, it has great project and large investment,therefore, it is particularly important to optimal design of dam section. Because a lot of heat generated by the cement hydration heat within the dam, and the layer between the new and old concrete may produce different temperature, it could lead to larger temperature stress,may even cracks. In this paper, the main research contents:(1) Design of this article main includes overflow dam, non-overflow and flushing sluice.Design of overflow dam, select the appropriate overflow weir surface curve and dam section,the width and crest elevation of overflow dam according to requirements of the spillway and generating head, select the appropriate energy dissipation type, achieve discharged volume can connect smoothly with downstream river flow. Initially selected trajectory bucket type energy dissipation as energy dissipation type, calculate the anti-slide safety coefficient based on the formula of stability against sliding, and analysis the stress according to the formula of stress calculation, make it meets standard requirements.(2) Selected basic parameters of roller compacted concrete combined the existing domestic engineering. Combined with the existing data, fitting the temperature change function in dam site, preliminary estimated concrete pouring temperature. Using ANSYS software, set up three-dimensional entity model according to the geometric parameters of the preliminary design of the dam in the feasibility stage. Through the simple simulation the process of dam construction, considering the concrete pouring temperature, the outside temperature changes, cement hydration heat and layered. Temperature field during the construction can be obtained by the thermal analysis. Extracted the results of temperature field, and applied structural analysis can be gotten temperature stress field during the construction. Initial temperature of dam relatively high. The temperature decreases as the dam’s rises, and high temperatures focus on interior. The main stress is compressive stress in the beginning, the gradual emergence of tensile stress and compressive stresses alternationwith the pouring process, it can provide the reference for later design.(3) The paper combined the actual project, using ANSYS optimization module, set up plane model according to the geometric parameters of the design condition and checking conditions of the dam in the feasibility stage,geometric constraints and state constraints are constraint conditions, section area as the objective function, use the first-order optimization method to optimize. According to the results of optimization, the area of the optimal section is reduced by 14.86% less than the area of the initial section in design condition, the area of the optimal section is reduced by 7.40% less than the area of the initial section in checking condition.When two conditions are met, the area decrease 7.40% than the initial cross-sectional area, it can greatly reduce the quantity, shorten the construction period, save engineering investment.