高海拔气候环境下碾压混凝土重力坝施工期开裂风险分析

Cracking risk analysis of RCC gravity dam during construction in high altitude climate

DG水电站位于高寒高海拔地区,气候环境复杂。为研究施工期碾压混凝土温控防裂问题,选取DG水电站厂房坝段为研究对象,采用三维数值仿真模拟技术进行施工期大坝温度场和温度应力计算,以及气温骤降、昼夜大温差对坝体影响的敏感性分析。研究结果表明:气温骤降、昼夜大温差在坝体表面分别产生约1.4,0.9 MPa的拉应力,易在坝体表面引起裂缝;为了减小由此引发的混凝土开裂风险,采用混凝土表面保温防护措施之后,坝体表面温度应力相应得到显著改善,拉应力分别减少至约0.3,0.4 MPa。

DG Hydropower Station is located in high altitude and cold area,and the climate environment is complex.To study the problem of concrete temperature control and crack prevention during construction,taking powerhouse section as the research object,the temperature field and thermal stress during the construction period of the dam were numerically simulated by the three-dimensional finite element method,and the sensitivity analysis of the impact of sudden temperature drop and temperature difference between day and night on the dam body.The research results showed that the sudden drop of temperature and large temperature difference between day and night produce tensile stress of approximately 1.40,0.9 MPa respectively on the dam surface,which was easy to cause cracks on the dam surface.In order to reduce the risk of concrete cracking caused by reasons above,the concrete surface thermal insulation protection measures were designed,the temperature stress on the dam surface was significantly improved,and the tensile stress was reduced to approximately 0.3,0.4 MPa respectively.