Numerical Calculation Research About Early-age Temperature Stress Of Inner Frozen Shaft Lining

The deep alluvium inner freezing walls are mostly constructed by high strength massive concrete. Earlier after concrete has been poured, the interaction between temperature fields of inner-wall and frozen wall will produce temperature stress, which needs to be controlled within an allowable range under the control of highest temperature in wall. This paper is based on the inner-wall of double-layer reinforced concrete shaft lining, the followings are main research contents.(1) Proceeding from the theoretical research of temperature field of concrete hydration heat, it expounds the application of heat conduction theory in concrete temperature field, solves initial conditions and boundary conditions of heat conduction equation and obtains the solution of finite element method in unsteady temperature field.(2) Calculation formulas of stress components are obtained based on the theoretical study of temperature stress. The result shows that the temperature stress consists of its own temperature stress caused by temperature difference between inside and outside wall, radial temperature stress, vertical temperature stress and tangential shear stress caused by thermal expansion.(3) Simulation software ADINA is adopted to make a numerical study of earlier temperature stress, which helps to expound the change rules of temperature and temperature stress under the influences of various factors, and effective methods are put forward to control the development of temperature. Research shows that:(1) The surface temperature is developing slower than inside temperature, the highest temperature is 79.94℃ and the maximum temperature difference is 38.01℃ when the thickness of inner-wall is 1.6m.(2)The thicker the inner-wall, the farther the distance from location of highest temperature to inside of inner-wall is, the smaller the convection coefficient of heat transfer, the closer the distance from location of highest temperature to inside of inner-wall is, the thickness of highest temperature accounts for about 12~34 percent of the thickness of inner-wall.(3)Controlling of the thickness of inner-wall can reduce the highest temperature and temperature difference obviously.(4)Hoop stress is biggest between all stress components, radial stress follows and vertical stress is smallest. When hoop stress is bigger than the tensile strength of C55 concrete, it is likely to induce the fracture of inner-wall.(5)Stress at inside inner-wall is bigger than outside generally, it shows that the temperature stress will lead to the fracture at inside firstly.(6)When the thickness of inner-wall reaches 0.8m, the temperature stress has exceeded the standard value of tensile strength of concrete.