Study On Thermal Stress Analysis Of Mixed Gentle MgO Swelling Concrete Structure And Its Effective Stress Method

A state-of-the-arts of the mixed gentle MgO of mass concrete technique in dam engineering are reviewed. The merits and defects of the traditional analytic method are discussed. According to the conception of microlevel or mesolevel mechanics and multi-phrase porous media, the study of concrete thermal stress with mixed gentle MgO are generally carried out in this dissertation. The purpose of the dissertation lies on the theory, algorithm and its application. The main contents are as follows:Firstly, the traditional analytical method of thermal stress of mass concrete with MgO are briefly induced. By initial strain method, the thermal stress of Longtan's roller compacted concrete gravity dam is analysesed. The author suggests that Gentle MgO autogenous expansive volume can be denoted by experimental testing table.Secondly, the early age adiabatic temperature development of concrete is investigated. The apparatus are set up for measuring temperature rise of 11 types concrete specimen. Based on hybrid experimental-numerical technique, the compensative correct factor for the experimental data is present. The influence of experimental error is discussed.Thirdly, the influence of gentle MgO expansive volume in different part and its adjustable delaying are the two keys in MgO concrete technique. The effect of the thermal stress of mixed gentle MgO concrete slab are studied in detail. Mixing with MgO in concrete dam can make tensile stress lessen in structure. It is important to ensure that the swelling of MgO must be coincidence with up-down different slabs each other. The results show the property of mixed MgO concrete thermal stress.Fourthly, accordance with the random particle model in micromechanics, the new cement paste matrix swelling model has been expressed, which is suitable for MgO concrete. This model can distinguish between the aggregate and paste matrix in MgO concrete.Finally, effective stresses method of thermal stress analysis to mixed gentle MgO expansive concrete structure is first presented. Based on Biot-Coussy theory, the governing equation and its boundary condition are established. With the application of the weighted residual method, the FEM formula are deduced. The relative FEM procedure is decoded. Some examples prove the new method correctness.