基于一次计数抽样检验的现场混凝土强度特征值推定方法

Estimation Method of Characteristic Value of Concrete Strength in Situ Based on Single Sampling Inspection by Attributes

回弹法检测现场混凝土强度具有对结构构件完全无损伤、可抽样数量多、测区布置灵活的优点,但其检测强度的均值和方差均可能存在较大偏差,故采用计量抽样检验方法推定的检测批强度特征值的准确性较差。根据一次计数抽样检验原理,在分析比较抽检特征曲线的基础上,以不合格品率为0.1时的接收概率为50%(置信水平为0.5)为原则,建立了检测批混凝土强度特征值的推定方法。通过抽检特征曲线对比和实例分析表明,该方法的推定结果与基于贝叶斯方法的计量抽样检验推定结果基本相当。提出了评定检测批混凝土强度时回弹测区的优化布置建议,并提出了回弹法计数抽样检验结果的钻芯修正方法。本文建议方法具有概率定义准确、避免强度分布类型假定和方差计算、减少钻芯校核数量等特点,可在工程质量符合性评定和既有结构安全性评定时采用。

The rebound method has the advantages of no damage to the structural components,a large number of samples and flexible layout of the test area.However,the mean value and variance of the inspected strength may have a large deviation,so the accuracy of the strength characteristic value of the inspection batch estimated by the sampling inspection by variables is poor.According to the principle of single sampling inspection by attributes,based on the analysis and comparison of sampling characteristic curves,the estimation method of characteristic value of concrete strength of inspection batch is established considering that the acceptance probability of 0.1 unqualified product rate is 50%(the confidence level is 0.5).The comparison of sampling characteristic curves and case analysis show that the estimation results of the proposed method is basically equivalent to that of sampling inspection by variables based on Bayesian method.Suggestions are put forward for optimizing the layout of rebound test area when evaluating the strength of test batch concrete,as well as the core drilling correction method for inspection results of rebound method by sampling inspection by attributes.The proposed method has the characteristics of accurate probability definition,avoiding the assumption of strength distribution type and variance calculation,and reducing the number of core drilling checks.It can be used in engineering quality compliance assessment and existing structure safety assessment.