The Application Study Of MgO Concrete To Solve The Problem On Thermal Stress Of Gravity Dam

The problem of mass concrete's thermal stress has great significance for the project design and construction, which had obtained a series of results, and got the application in the practice. But, if we could further improve the construction speed and lower the build cost, that will have very greatly economic and social value. Ever since our country constructed the Bai Shan's gravity arch dam, gradually discovering that the Micro-expansion MgO concrete has the function of compensated thermal stress. Basing on research a great deal of datum and relatively literatures, this paper comprehensively discussed to utilize the Micro-expansion MgO concrete to solve the problem of mass concrete's thermal stress. It is of greatly actual meaning to generalize and advance the Micro-expansion MgO concrete thermal stress compensated technique on dam build.It is referring to knowledge of many fields and subjects that the Micro-expansion MgO concrete thermal stress compensated technique on dam build. Being from the technique current development level and the usage of it, this paper systemically disuses quite a number of concernments of the technique, for which count much of make MgO, MgO cement and concrete, the thermal and mechanical parameter of MgO concrete, the soundness of the Micro-expansion MgO concrete and the MgO cement construction equipments. The problem of the soundness of the Micro-expansion MgO concrete is a key factor for the Micro-expansion MgO concrete technique on dam build. Hydraulic engineer is general widespread think that there should be no soundness problem of the concrete with MgO upper limit 5%.As the improvement on the experimental method, the more engineering practice experience and the new topic in the project practice, the restrict of the concrete with MgO upper limit 5% must be breakthrough.Essentially, the expansion of the MgO concrete is the result of the chemistry reflection of the concrete material, among them, for the reason of the concrete expansion is the MgO to hydrate. In our country, the roller compacted concrete dam (RCCD) mixes a great lot of fly ashes and the more fly ashes can restrain the MgO expansion in the concrete. Therefore, under the concrete soundness condition, appropriately heighten the MgO content in concrete then can satisfy the request of quickly build and simplified temperature control measures of the RCCD without transverse seam. In this article, according to heat conduction theory, elastic creep theory and finite element theory, the temperature field and thermal-creep-stress field programs are compiled. The programs are validated by contrast the result of the program computational to the result of the engineering surveyed or theoretic analyzed. Constructionand operation stage temperature field and thermal-creep-stress field of the roller compacted concrete cofferdam without transverse seam, whose concrete contains high fly ashes and with 6% MgO, are simulated and analyzed by the programs, which conclude the thermal stress expansion capacity and area by utilized the MgO concrete, aim at provide some reference and results to the usage of MgO concrete in gravity dam.