基于遗传算法的大体积混凝土热力学参数反演分析

Inverse Analysis of Mass Concrete Thermal Parameter Based on Genetic Algorithm

为准确快速确定混凝土热力学参数中难以确定的绝热温升、导热系数、表面放热系数及反应速度,以云南普立大桥散索鞍支墩基础大体积混凝土施工实测温度为基础,采用遗传算法进行混凝土热力学参数的反演分析,并根据反演参数建立三维有限元模型预测后续混凝土施工中的温度场,然后通过混凝土内部实测温度及应力验证预测结果。最后依据预测结果,在混凝土浇筑早期采用表面降温,内部布设冷却水管的措施有效减小了内外温差并防止了裂缝产生。结果表明:混凝土内部温度达到峰值时表面拉应力最大值为1.5 MPa,出现表面裂缝的可能性较小;混凝土浇筑3d后,抗裂指数都在1.5以上,一般不会产生裂缝;基于反演参数的温度场计算值与实测值吻合良好。

In order to accurately and efficiently determine concrete thermal parameters ,such as adiabatic temperature rise , the thermal conductivity , the surface heat transfer coefficient and reaction speed ,which were difficult to be obtained ,the genetic algorithms were applied in inverse analysis of concrete thermal parameters according to the measured temperature during the mass concrete construction in Puli bridge vice cable saddle pier foundation , Yunnan Province . Meanwhile ,three‐dimensional finite element model was established to predict temperature field in follow‐up concrete construction and verified by the measured temperature and stress . Finally , according to the predicted results ,surface cooling and cooling water pipes inside can effectively reduce the temperature difference betw een inside and outside ,and prevent cracks in early stage after concrete pouring .The results show that the surface maximum tensile stress is 1 .5 MPa w hen internal temperature of concrete reaches peak value ,that means none possibility of cracks . After concrete pouring 3 d , crack resistance index is greater than 1 .5 , that indicates few possibility of cracks .The calculation value of temperature field coincides well with the measured value based on the inverse parameters .