Hydraulic Concrete Thermal Stress Analysis And Temperature Control And Crack

The large volume concrete occupies an important position in the modern industry and the public building, especially the large volume concrete structures of water engineering, usually carrying on the big piece in the whole sprinkle to build in a short time .This structure will release a great deal of hydration heat to cause the temperature of concrete to go up, bigger temperature gradient inside the concrete make the structure produce temperature stress, build up the drying shrinkage in the meantime and etc, then cause crack;These cracks usually bring engineering hazards in different degree, some of them even endanger the safety of the building. Therefore, the control on temperature stress and the temperature crack is an important problem in the construction of large volume concrete structure.This thesis aims directly at this problem, combining the floodgate engineering of bai-sha reservoir,to research thoroughly on the temperature stress and the temperature anti-crack of large volume concrete structure of water engineering.the main contents has a few aspects as follows:1. Utilize powerful front-post dealing function and compute ability of the finite element software ANSYS to precisely imitate the construction process of the large volume concrete,comprehensive consider elastic modulus of the concrete hydration heat going up air temperature and water temperature with the variety of the age period, construction condition of sprinkles per layer and per piece the after sprinkle build technique and so on , to come true the finite element calculation on concrete structure temperature field and stress field .2. In consideration of the complexity of the concrete aqueduct cooling off and the limit of the finite element calculation in the existing calculator function on the aqueduct cooling concrete , lead-in equations of isoeffect heat conduction to cool off concrete ,then carry on simulation calculation.3. To think over the complicated creep characteristics of concrete , utilize the open program interface of ANSYS, adopt VB language to compile user subprogram, and carry out second-time exploitation, to come true the increment calculation of concrete elasticity creep thermal stress by ANSYS.4. According to characteristics of the water engineering concrete tructure, adopt reasonable humidity move-shift mathematic model, combining the beginning conditions and the boundary conditions, synthesizing to consider various factors of influencing humidity diffusion, approach the mathematical expression of concrete humidity diffusivity and the surface moisture coefficient of crossing over in the calculation of humidity field;get a set of relatively integrity calculation system of concrete humidity diffusion and drying shrinkage stress.5. Combine the bai-sha reservoir floodgate engineering, put forward a set of relatively consummate temperature control design method about floodgate concrete construction and the operation projectat carrying on dynamic control blindunder construction , attain to not only keep the floodgate concrete from appear the temperature crack effectively, but also overcome the blindness on adopting temperature control and anti-crack under construction.Combining the whole theory research with actual engineering closely , not only carry on a thorough research on controled measures , but also verify accuracy of theories in practice, and build up abundant of the spot construction experience.