Research On Temperature Control Technology Of Mass Concrete In Winter Construction In Alpine Area

Temperature crack is the main form of failure of newly poured mass concrete,and controlling the production of temperature crack becomes an important subject to ensure the safety of mass concrete structure.From the principle,the control temperature crack produces the essence is to control the temperature change inside and outside the concrete,the mass concrete pouring molding and the post-maintenance stage structure if produces the larger table temperature difference(generally more than 25?),the concrete internal and external tensile stress will soon be unbalanced,after breaking through the ultimate tensile strength,the surface concrete first produces micro-cracks,It may then even develop into cracks and deep cracks throughout.The average winter temperature in the northwest Alpine region is low,the temperature difference between day and night is huge,and it is especially important to adopt strict temperature control measures after pouring large volume concrete.Based on a large volume concrete winter pouring project in Lanzhou New area,this paper explores the variation law of the internal temperature field of the newly poured mass concrete under the location environment under the condition of finite element simulation calculation and field temperature measurement test.And the practical effect of temperature regulation of newly poured mass concrete by using extruded Polystyrene board(XPS plate)and HHC-S type hydration thermal inhibitor,and to find the most efficient and economical temperature control measures.The main contents of this article are as follows:1.This paper introduces the basic theory and method of calculating the temperature field of concrete,compares the finite element method with Monte Carlo method,and holds that the finite element method can adapt to the cell division and calculation of various irregular structures,and has great advantages in the coupling calculation of each factor.The advantage of Monte Carlo calculation method is that it has high calculation accuracy.,and the calculation accuracy is easy to control.In this paper,the finite element simulation software MIDAS Civil is used to simulate the temperature field of concrete under the complex environment of Alpine area.2.Starting from the idea of "external protection internal Control",this paper uses XPS extruded polystyrene board to regulate the internal and external temperature and heat dissipation of concrete,and uses HHC-S type hydration thermal inhibitor to interfere with the hydration process of concrete in order to achieve the goal of reasonable temperature control.The performance test of hydration thermal inhibitor at normal temperature was carried out indoors,and the test results showed that the hydration thermal inhibitor had the effect of inhibiting the hydration reaction of cement,delaying the arrival time of peak temperature and reducing the peak temperature,whether it was mixed with concrete or cement slurry.3.The use of MIDAS Civil simulation of the field test environment under the conditions of different mold temperature,different insulation layer thickness of the internal temperature field changes,and from the temperature rise rate,temperature peak,the temperature difference of the table analysis of the simulation results,it is concluded that the field test using concrete into the mold temperature of 10?,The thickness of 5cmXPS plate can effectively control the conclusion that the temperature difference of the scale is produced after the pouring of the Test pier.The adiabatic temperature rise curve of concrete after mixing with hydration thermal inhibitor was simulated by laboratory test,and the simulation results were analyzed by simulating the temperature field of the field Test pier.4.In Lanzhou New district,a construction site of mass concrete test pier pouring and temperature measurement test.On the one hand,the test results prove the high reliability of the finite element simulation results,on the other hand,the validity of the two temperature control measures is verified,which provides a reference for the construction of mass concrete in this area.