基于均匀设计及BP神经网络的大体积混凝土热学参数反分析

Inverse analysis on thermal parameters of mass concrete based onuniform design and BP neural network

为了解决桥梁工程大体积混凝土热学参数失真的问题,提出一种基于均匀设计理论与BP神经网络的大体积混凝土热学参数反分析方法。该方法通过BP神经网络建立大体积混凝土温度场与热学参数的非线性关系;BP神经网络的训练样本由均匀设计方法确定;在BP神经网络训练阶段,采用附加动量法对网络结构进行优化;对优化前后的误差曲线及多次训练过程的分析结果表明:附加动量法可明显缩短网络训练时间,多次训练过程的平均绝对百分比误差值及均方根误差值稳定。在太洪长江大桥散索鞍支墩承台大体积混凝土施工中反演了绝热温升、反应速率常数及导热系数,基于反演值的温度计算值与现场实测值吻合较好,温度峰值最大误差仅为1.1℃。基于均匀设计理论与BP神经网络的大体积混凝土热学参数反分析方法可行,且反演过程稳定收敛,反演精度高,应用于指导温控施工能降低大体积混凝土开裂风险。

In order to solve the problem of distortion of thermal parameters of mass concrete in bridge engineering,an inverse analysis method of thermal parameters of mass concrete based on uniform design theory and BP neural network was proposed.This method uses BP neural network to establish the non-linear relationship between the temperature field and thermal parameters of large-volume concrete;training samples of BP neural network are determined by uniform design method;during the training phase of BP neural network,additional momentum method is used to optimize the network structure;The error curve before and after optimization and the analysis results of multiple training processes show that the additional momentum method can significantly shorten the network training time,and the average absolute percentage error value and root mean square error value of the multiple training processes are stable.The adiabatic temperature rise,reaction rate constant,and thermal conductivity were inverted during the construction of the bulk concrete of the supporting platform of the saddle pier of the Taihong Yangtze River Bridge.The calculated temperature based on the inversion value agrees well with the actual measured value,and the maximum temperature peak error is only 1.1℃.Therefore,the inverse analysis method for thermal parameters of large-volume concrete based on uniform design theory and BP neural network is feasible and the inversion process is stable and convergent,and the inversion accuracy is high.It can be used to guide the temperature-controlled construction to reduce the risk of large-scale concrete cracking.