| The residential building in the case is a103m super high-rise building with frame-shear wall structure, pile foundation and raft plate. The thickness of raft plate is1.9m, and the strength grade of concrete is C35. As a result, the heat produced by the hydration of large-volume cement during construction will definitely affect the infrastructure. Therefore, it is necessary to study the heat of hydration and find an effective solution.At first, the adiabatic temperature rise of the building’s foundation slab and the temperature rise of hydration heat after the application of comprehensive cooling measures are calculated through ANSYS simulation; then, this paper describes construction technology, cooling measures, methods of temperature measurement and analysis result of measured temperature in the case; finally, the influence of air temperature, thickness of structure and strength of concrete on the maximum temperature at the center of foundation slab and the temperature rise of hydration heat are analyzed. The following conclusions are made: 1. The vertical temperature distributions of the raft are as follows:(l).there is a high-temperature area with almost zero temperature gradient in concrete, where takes up a half of laminate construction thickness;(2). High-temperature was in the middle in the first five days, conforming to the rule of high temperature in middle, low temperature in base and interarea;(3). With the growth of age of concrete, high-temperature area moves down gradually. The back surface of high-temperature area moves down to base in the14th day, when the highest temperature in base, middle taking second place, lowest temperature in interarea2. The influence of air temperature on temperature rise of hydration heat (assume pouring temperature is equal to air temperature) is as follows:(1) the maximum temperature at the center of foundation slab, the pouring temperature and the temperature rise of hydration heat all increase with air temperature. The pouring temperature has a straight climb, while the other two rise in a curve which is almost a straight line;(2) As air temperature varies, the change value of the maximum temperature at the center of foundation slab is the sum of the change value of pouring temperature and that of the temperature rise of hydration heat caused by the change of hydration reaction rate. The change value of the maximum temperature at the center of foundation slab is almost the same as the change value of pouring temperature, because the change value of the temperature rise of hydration heat has a very limited impact;(3) The change value of the temperature rise of hydration heat caused by the change of hydration reaction rate has a negative linear correlation with air temperature. If the air temperature is larger than50℃, the change value of the temperature rise of hydration heat will be zero, and the change value of the maximum temperature at the center of foundation slab is equal to the change value of pouring temperature.3. The influence of thickness and strength grade of concrete structure on temperature rise of hydration heat is as follows:(1) The maximum temperature at the center of foundation slab increases with the growth of thickness and strength grade respectively, vice versa;(2) As the structure thickness increases, the rise speed of the maximum temperature at the center of foundation slab gradually declines. When the structure thickness is greater than6m, the rise speed will be zero and the maximum temperature at the center is close to adiabatic temperature rise.4、With the results of research theory in this paper as a guide for practical engineering, it can be seen that the temperature control of base plate in practical engineering is effective. Besides, there has not appeared any cracks in the structure during the nearly two years of usage. It is an illustration that the theoretical analysis is correct and has certain guiding significance to the temperature control of similar structure. |
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