Research Of Temperature Control Technology Of Mass Concrete Anchor Of Lishui Bridge

With the rapid development of bridge project in China in recent years, the mass concrete used in bridge engineering is more and more widely, and temperature control problem dued to the hydration heat has aroused great attention. In the construction process of mass concrete, the cement hydration heat caused a sharp temperature rise inside of concrete. for the poor thermal conductivity of concrete,the temperature built up inside, while the temperature surface exposured the air is lower, resulting in temperature difference internal and external of concrete, caused tensile stress internal of concrete. If the tensile stress exceeds a certain limit, cracks will form. By taken Lishui Bridge HuaYuan massive concrete anchor as research object, its temperature monitoring temperature control design and summarizes the changing law of temperature and stress within the mass concrete, the article carried out the following studies:1. Introduce cracks in mass concrete reasons and temperature field analysis of the basic principles.Then take Lishui Bridge HuaYuan massive concrete anchor as the project background,analyze the parameter sensitivity of layer thickness of concrete, Spiking pulverized coal ash or not, water flow rate of Cooling Water Pipe, arrangement direction of cooling water pipe. The results show that: the thinner the layer is , the lower the maximum temperature; pulverized coal ash has an important influence to the highest temperature inside the concrete, can effectively reduce the temperature peak;the maximum temperature inside the concrete reduces with the increase of the cooling water flow rate.However, after exceeding the critical flow rate, the cooling effect of is not obvious. Sensitivity Analysis of the above can be reference for other similar projects to develop the right construction plan.2. Established the three-dimensional finite element model considered the time dependent materials, air temperature, the effect of cooling water of Lishui Bridge HuaYuan massive concrete anchor by using the software MIDAS/Civil, carried on the simulation analysis of temperature field of construction process of Lishui Bridge HuaYuan massive concrete anchor,then determined the design of temperature control, developed a temperature indicators and temperature control program.The results showed that temperature are controlled within the permissible range. 3.Realized Informationization of mass concrete and achieved effective temperature control of construction of mass concrete based on real-time monitoring temperature and feedback analysis. Comparisons showed that simulation results agree well with the measured values, so computer finite element program can be used to conduct simulation analysis of the temperature field of hydration heat of mass concrete ,so as to instruct the design and construction, and control the appearance of cracks of mass concrete effectively.4. Proposed some feasible suggestions on the selection and strict control of raw materials, layer pouring intermittent period, choice of conservation measure.to other similar projects.