Research On Optimization Of Temperature Control Curve Of Mass Concrete For Arch Dam And Its Engineering Application

Temperature control of mass concrete is the focus of arch dam construction.Water cooling is an important means to achieve temperature control and crack control.Intelligent water-cooling technology is a new temperature-control method that can overcome the problem of untimely and inaccurate temperature data acquisition,achieve fine control of water flow and process,and improve temperature control accuracy.It has been applied in the existing Xiluodu arch dam and is currently being applied to arch dams such as Wudongde and Yangfanggou.At present,although the intelligent water supply has been realized,the cooling process of the arch dam generally adopts the "three-phase and nine-stage" water-cooling method.In practical engineering applications,there is a general problem of temperature rise during the temperature control phase and large fluctuations in the stress development process,resulting in a sharp change in the crack safety factor,which is unfavorable for crack control.Therefore,further optimization of the temperature control process is of great significance to improve the technical level of arch dam construction.Based on the simulation of thermal stress,this paper optimizes the temperature control curve of concrete arch dam under the background of intelligent water flow.The main work of this paper is as follows:(1)This paper summarizes and analyzes the temperature control process of seven high-arch dams in China during construction,and clarifies the common characteristics of temperature control curves.The Wudongde arch dam was selected as a typical project for temperature and stress process research.Through the simulation calculation and monitoring analysis of the riverbed dam section,steep slope dam section,corridor and mesopores of Wudongde Arch Dam under the existing temperature control curve,it is pointed out that the stress meets the crack resistance requirements,but the temperature is prone to occur in the process.The rebound,the stress fluctuation is large,especially the problem that the safety factor of the second cold is too small.(2)Based on the concept of cooling water flow of "small temperature difference,early cooling,slow cooling",the concept of stress difference averaging is proposed.By comparing and analyzing the three-stage nine-phase,linear,concave,and convex-type temperature control curves,the concave curve is optimal.The parabolic model was chosen to optimize the temperature control process,and the method of optimizing the temperature control curve and the optimization curve equation were proposed.(3)Taking the Wudongde arch dam as an example,through the comparative analysis,the temperature distribution curve and the stress distribution and variation law under the optimized temperature control curve are obtained for the riverbed dam section,the steep slope dam section,the dam corridor and the mesoporous area.The results show that the temperature control is carried out according to the optimized temperature control curve.The safety factor is generally greater than 1.8,the temperature and stress curves are smoother,and the safety factor fluctuation is small,which is beneficial to the safety control of the arch dam during construction and operation.