大体积混凝土热膨胀系数反演分析

Inverse Analysis of Thermal Expansion Coefficient of Mass Concrete

混凝土的热膨胀系数是大体积混凝土的温度应力仿真计算中的一个重要参数.现结合某建设中的特高拱坝,利用埋设在混凝土内的无应力计测值和相对应的温度值,采用最小二乘法进行混凝土热膨胀系数反演分析.分别选取中期冷却、二期冷却的典型降温过程和一期冷却的典型降温过程中无应力计测值和相应的温度测值进行热膨胀系数反演.分析结果表明,由于该特高拱坝的自生体积变形需要较长时间才能稳定,不宜采用一期冷却的降温过程来反演混凝土的热膨胀系数,而应采用中期冷却、二期冷却的典型降温过程来进行反演.所得参数对大坝混凝土的温度应力仿真计算具有一定参考价值.

The coefficient of thermal expansion is one of important parameters in simulation calculation of thermal stress for mass concrete. This article combines with a certain ultrahigh building arch dam, making use of the records of non-stress meter and corresponding temperature values, then the least square method is adopted to inverse analyze. The different cooling phases are chosen respectively with the records of non-stress meter to calculate. The outcome indicates that it is suitable for inverse analysis at the medium and second cooling phases, and is not suitable at the first cooling phase due to the long time of autogenous volume deformation in ultrahigh arch dam concrete. The gained parameters will provide specific reference to simulation calculation of thermal stress.