寒潮对导墙坝段施工期温度应力影响研究

Temperature stress effect of cold waves on the guide wall of a dam during construction period

导墙外侧边界对外界温度变化非常敏感,寒潮使周围环境温度骤降进而将导致混凝土表面和内部呈现较大温差,引起温度应力过大和出现温度裂缝等问题。针对旬阳水电站右导墙坝段,采用三维有限元法,模拟坝段施工过程,对无寒潮无保温、有寒潮无保温和有寒潮有保温3种工况进行温度场和应力场仿真计算研究。结果表明:寒潮过程对坝段表面温度影响较大,在坝段表面产生了较大拉应力,对坝段内部温度和应力几乎没有影响;寒潮发生时,采用5 cm厚的泡沫塑料板进行保温,可使坝段表面温度提高8.0℃左右,表面最大应力小于过流面抗冲磨混凝土允许拉应力,能有效避免寒潮引起的温度裂缝。研究成果可为类似工程提供借鉴和参考依据。

The external boundary of a dam guide wall is very sensitive to temperature change.Cold waves will cause sudden temperature drops that lead to large temperature gaps between the surface and the internal of the concrete guide wall,resulting in excessive temperature stress and temperature cracks.Taking the right guide wall of Xunyang Hydropower Station as an example,the three-dimensional finite element method was used to simulate the construction process of this dam section.The temperature field and stress field were simulated under three scenarios,namely,no insulation and no cold wave,no insulation with cold wave and insulation with cold wave.The results show that the cold wave has a great influence on the surface temperature of the wall,and produces a large tensile stress on the surface;however,it has little effect on the internal temperature and stress of the dam section.When the cold wave hits,the thermal insulation of Polyfoam sheet with a thickness of 5 cm can increase the surface temperature of the wall by about 8.0℃,and the maximum stress on the surface is less than the acceptable tensile stress for abrasion-resistant concrete on the overflow surface.So this measure can effectively avoid the occurrence of temperature cracks caused by cold waves.The research results can provide some reference for similar engineering projects.