| 摘要: |
| 【目的】研究氧化镁微膨胀混凝土对温度应力的补偿特性，为简化大体积混凝土温控防裂措施提供理论依据。【方法】在充分分析和研究温度应力补偿计算方法和氧化镁微膨胀混凝土自生体积变形特性的基础上，针对某碾压混凝土重力坝，考虑混凝土热、力学参数随龄期变化及混凝土实际浇筑过程对温度应力的影响，利用大型商业有限元计算软件ANSYS平台开发出的温度场与温度应力场仿真计算程序，对掺与不掺氧化镁2个对比方案的大坝碾压混凝土温度应力进行计算分析。【结果】掺氧化镁方案中施工期末整个坝体碾压混凝土出现体积膨胀，最大膨胀变形量超过70.0×10-6；氧化镁微膨胀混凝土对坝体基础约束区中心部位应力状态有明显的改善效果，最大拉应力减小约1.0 MPa；但对脱离约束区的坝体混凝土应力的改善效果非常有限。【结论】在坝体约束区采用氧化镁微膨胀混凝土，可以达到简化温控防裂措施、降低建设成本、加快施工速度的目的。 |
| 关键词: 氧化镁混凝土 微膨胀 自生体积变形 温度应力 补偿效应 |
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| 基金项目:国家自然科学基金项目(51009116)；中央财政支持地方高校发展专项（106-5X1205）；陕西省重点学科建设专项（106-00X903） |
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| Compensative effect of MgO micro-expansive concrete on thermal stress |
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| Abstract: |
| 【Objective】This research studied the compensation characteristics of MgO micro-expansive concrete to simplify temperature control measures for crack prevention.【Method】Based on full study of thermal stress compensation method and autogenous volume deformation characteristics of MgO micro-expansive concrete,and considering the variation of concrete mechanical parameters with time and impacts on thermal stress of concrete pouring process,the temperature field and stress field of a roller compacted concrete gravity dam were analyzed with two contrast schemes by a temperature field and thermal stress field simulation program developed on ANSYS platform.【Result】The results showed that concrete of the whole RCC dam mixed with MgO had a micro-expansive volume at the end of construction with a maximum expansive deformation of higher than 70.0×10-6.Stress state of central part of dam foundation restraint area was significantly improved using MgO micro-expansive concrete with a maximum tensile stress decreases of about 1.0 MPa,but the improvement of dam concrete out of restraint area was limited.【Conclusion】Using MgO micro-expansive concrete in dam restraint area can predigest temperature control measures,which would achieve the purpose of reducing constructing cost and expediting construction. |
| Key words: MgO concrete micro-expansive autogenous volume deformation thermal stress compensative effect |
