【作者】 司政；

【导师】 陈尧隆；

【作者基本信息】 西安理工大学 ， 水工结构工程， 2006， 硕士

【摘要】 自上个世纪70年代在我国吉林省东北严寒地区修建的白山电站重力拱坝中发现氧化镁有补偿收缩效果以来,很多设计部门及技术人员对其进行了深入的研究。研究结果表明:氧化镁对大体积混凝土温度应力有很明显的改善,进而简化温控措施,以达到降低建设成本、加快施工速度的目的。现今氧化镁混凝土已经在很多水利水电工程中得到应用,并获得了成功。本文综述了大体积混凝土氧化镁筑坝技术的由来、国内外研究现状、优势及存在的主要问题;叙述了掺氧化镁微膨胀混凝土的膨胀特点、基本力学性能及长期耐久性能;推导了计算温度场及温度应力场的全部公式。对现有计算氧化镁混凝土自生体积变形的几个典型模型进行了深入的研究和分析,阐述了它们各自的优缺点,最终选定动力学模型作为计算氧化镁混凝土自生体积变形的数学模型。在此基础上,作者根据热传导理论、弹性徐变理论及有限元理论,编制了计算氧化镁微膨胀混凝土温度场及温度应力场的程序。用此程序对龙滩水电站下游碾压混凝土围堰进行计算,并与实测结果进行对比,最大误差均在5%之内,由此可以说明编制程序的正确性。运用编制的程序对一碾压混凝土重力坝施工期和运行期温度场、徐变应力场进行了全过程的仿真分析。为了说明氧化镁对大坝混凝土温度应力的补偿效果,将大坝混凝土中掺与不掺氧化镁进行对比。由计算结果可以得出:氧化镁微膨胀混凝土三年可达160～180个微应变,一年的膨胀量可达到最终膨胀量的80%,后期膨胀渐趋稳定,完全符合氧化镁微膨胀混凝土的膨胀特点。计算结果还表明掺氧化镁后,在基础垫层及强约束区补偿较为明显,补偿应力最大可达1.0MPa ,而在弱约束区及非约束区应力无明显变化。此次计算结果可以为简化温控措施提供依据,具有较大的实际意义。更多还原

【Abstract】 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.更多还原