Study Of The Compensative Effect Of Micro-Expansive Concrete In Thermal Stress

Since 1970s, in our country JiLin province northeast chilliness region discovered in the BaiShan power station gravity-arch dam the magnesia had compensative effect, therefore a great many design departments and technologist proceeded a deep research. Findings indicate: Magnesia has a evident improvement on mass concrete temperature stress, and predigest the temperature-control measures, which would achieve the purpose of depress constructing cost, expedite construction velocity.Nowadays magnesia concrete has applied in a great many hydroelectric projects ang achieve a lot success.In this paper the author overviews mass magnesia concrete dam thchnical origin, the present status here and abroad, and available primal problems; descripts theexpansive character of magnesia concrete, fundamental force performances and long-term lasting quality, derivates all the equations of temperature field and temperature stress field, analysises the existing canonic calculating autogenous volume deformation model of the micro-expansive concrete, at last select the expansion model of dynamics for calculating. Based on the heat transfer theory elasticity creep theory and theory of finite element, the author analysis the LongTan hydroelectric power station by the programs, and contrast with the actual measurements, the maximum error do not exceed the confines of 5%, proving the programs are right.Apply the programs to analysis the temperature field and temperature stress field of a roller compacted concrete gravity dam. In order to show the compensative effect of magnesia in dam concrete, design tow contrast schemes of the concrete:one is mixed magnesia and the other is not. Results indicate: The micro-expansive concrete can obtain 160～180 microstrain through 3 years, the expansion of one year can reach 80% of the ultimately expansion, and the after expansion tend towards stability. All these concide to the expansion character of the micro-expansive concrete. The results also show: at foundation bed and strong peg region of the dam the conpensation stesscan reach 1.0 Mpa, whereas at feebleness constraint region and not constraint region the stress have no evident variety. The results can supply gist for predigesting temperature-control measures, which possess major practice sense.