Research On Crack Control Technology Of Mass Concrete Of The High Altitude Environment’s Winter

Under the Qinghai-Tibet Plain this kind of special atmospheric environment, for a one-time pouring of mass concrete research is less and still was in particular imperfect regarding the durable concrete under this kind of condition early dehiscence mechanism research, therefore this article embarked on Qinghai-Tibet Plateau this atmospheric environment and unifies the bridge pier winter construction the project background conducts the research from the mass concrete temperature field and the temperature stress distributed rule to the concrete early time dehiscence. On the main task of this paper specifically as follows:1. Firstly, with the thermal conduction between the concrete outside the general regularity were studied and introduced the mass concrete hydration heat of cement, concrete adiabatic temperature rise calculation formula and the temperature field, stress field finite element calculation principle, at the same time also expounds the different boundary conditions in thermal properties of concrete and temperature diffusion law and the boundary condition is the approximate processing method.2.This article based on the heat transfer theory, Making use of the finite element software, the pile cap, the bridge pier concrete temperature field and the stress field carries on the finite element simulation computation, the obtained results are compared with the experimental data, variation law of concrete temperature field and stress field are analyzed, the reasons of the large volume concrete in winter construction of surface cracking are summed up and the above research will have a certain reference value in large volume concrete cracking.3. This article has collected the correlation grit in the scene and so on each raw material data as well as the Xining basic meteorological data has provided the essential parameter for the following simulation computation. This paper also developed a test plan and test pier piers according to size in its interior and surface area layout of measurement points, is aimed at the pier in the pouring process for temperature monitoring and data collection.Through the Experimental study found that the surface of the curing temperature and ambient atmospheric to prevent cracks in the concrete temperature has a close relationship, especially in the winter construction of mass concrete, require its surface for good heat conservation, so as to reduce the temperature difference between inside tablein order to prevent the concrete surface cracking.4. Based on the experimental study data and the model analysis result, this article finally put forward the correlation proposal and the measure to time the mass concrete winter construction crack prevention; at the same time in this paper the influence of concrete early cracking factors make correlation analysis. The key consideration and the pouring temperature of the concrete under low temperature construction, curing temperature, heat storage and holding time parameters on the maximum temperature rise inside the concrete, as well as the size of the surface tensile stress, and draw some useful conclusions. Applying these conclusions to prevention in winter construction of large volume concrete temperature crack, but also for future engineering practice has certain guiding role.