大体积混凝土温度应力场有限元分析与开裂确定

Massive concrete temperature stress field simulated by finite element analysis and crack

本文利用实测大体积混凝土表层的温度发展规律曲线进行混凝土匹配养护,测试不同龄期混凝土静弹性模量和劈裂抗拉强度。利用实测温度校正的ANSYS数值分析的大体积混凝土温度场和混凝土静弹性模量等作为模拟参数,进行ANSYS数值分析大体积混凝土温度应力场。实验结果表明,混凝土在匹配养护条件下,静弹性模量早期发展很快,之后增长速率逐渐减小,3d可达28d的80.4%,同样,混凝土的3d劈裂抗拉强度(fts)可达84.5%。模拟结果显示:承台表面混凝土温度应力S1的最大值3d时达最大,为4.46MPa;3d时fts/S1值最小为1.12,此后逐渐增大,说明3d是混凝土最易开裂的时刻。对于底面全约束混凝土,温度应力最大值均集中在承台底部四周,这些部位为最易开裂部位。在混凝土表面养护条件良好的情况下,当fts/S1值大于1.12时,大体积混凝土表面不会开裂。

The temperature developing curve of mass concrete cover was measured on site and the temperature curve was used to cure concrete specimens.The split-tension strength and Young＇ s modulus at different ages were measured.The temperature distribution by finite software ANSYS corrected by measured temperature and Young＇ s modulus at different ages were introduced, and then the temperature stress field was simulated. Results showed that Young＇ s modulus under the matching curing developed fast,value at 3d reach 80.4% of 28d,after 5d,the value increased slowly.Concrete temperature stress S1 maximum of bearing platform surface at 5d reach max, is 5.12MPa.The split-tension strength at 3d appreciably high than temperature stress of beating platform surface,then difference increased with ages increment.When concrete curing condition is sound and the split-tension strength of concrete is higher than Sl,cover of mass concrete hardly cracked.In addition,temperature stress maximum focused on the around the bearing platform underside for underside all restriction.