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进行严寒地区碾压混凝土坝越冬层面温控防裂研究,为越冬层面温控防裂设计提供理论依据。针对严寒地区某碾压混凝土重力坝,考虑碾压混凝土热力学参数随龄期的变化、碾压混凝土浇筑进度对温度应力的影响,对碾压混凝土重力坝施工期和运行期全过程进行三维有限元仿真计算分析,着重分析越冬层面应力分布特征。结果表明:约束区和非约束区的越冬层面温度应力分布特征相似,但约束区越冬层面温度应力较大;未采取温控措施时,越冬层面上、下游侧铅直方向温度应力较大,致使越冬层面上、下游侧易出现水平裂缝;越冬层面中部顺水流方向温度应力也较大,因此中部易出现沿坝轴线方向裂缝。提出了采取表面保温、升温水管、微膨胀混凝土、设置水平人工短缝四种措施改善越冬层面的温度应力。采用表面保温和微膨胀混凝土可有效减小越冬层面上、下游侧和中部各个方向的温度应力;采用升温水管和设置水平人工短缝可有效减小越冬层面上、下游侧铅直方向应力。
The research on the temperature control and crack prevention of the over-winter level of RCC dam in cold region provides a theoretical basis for the design of temperature-control and crack-prevention during over-winter level. Considering the change of the thermomechanical parameters of the RCC with age and the influence of the RCC construction progress on the temperature stress in a certain RCC gravity dam, the three-dimensional finite element method is used for the construction and operation of the RCC gravity dam. Simulation calculation and analysis, focusing on analysis of winter stress distribution characteristics. The results show that the distribution characteristics of temperature and stress at the overwintering layer in the restrained area and the non-restrained area are similar, but the temperature stress in the constrained area is larger than that in the winter; when the temperature control measures are not taken, the vertical temperature stress in the upper and lower reaches of the overwinter is larger, On the wintering level, the horizontal cracks tend to occur on the downstream side; the temperature stress in the middle of the wintering level along the water flow is also large, so the cracks along the axis of the dam tend to occur in the middle part. The paper puts forward four measures to improve the temperature stress of overwintering surface by adopting the methods of surface heat preservation, water heating pipe, micro-expansive concrete and setting horizontal artificial short seam. The use of surface insulation and micro-expansive concrete can effectively reduce the temperature stress in all directions of the overwintering, the downstream and the middle; using the heating pipe and setting the horizontal artificial stitches can effectively reduce the vertical stress in the upstream and downstream of the overwintering surface.