小波包和功率谱密度分析法在混凝土龄期强度监测中的应用

摘要

利用压电智能骨料激发的应力波,对混凝土28 d内目标龄期进行信号监测试验研究,并通过功率谱密度和小波包能量分析法对混凝土龄期内监测信号进行分析.试验结果表明:混凝土目标龄期内,随着时间的逐渐增加,混凝土试件中传感器监测信号的小波包能量和功率谱密度的幅值随时间的变化趋势呈现出非线性增长,6 d和12 d是增长变化的分界点,其幅值分别达到了2.345×104 V2、3.923×104 V2和61.54 pV2/Hz,98.86 pV2/Hz.其试验结果与混凝土试件在实际养护过程中试件强度的变化规律具有很好的一致性.%The stress wave generated by a piezoelectric patch and signal monitoring testwere conducted in each target age within 28 d.Power spectral density and wavelet packets energy algorithms wereemployed to analyze the stress wave signals received by the sensors at concrete.It's showed from the experiment results that during the concrete curing period,the change of the wavelet packet energy of sensor signals and the power spectral density under structure natural frequency showed a nonlinear increase with time:and 6 d and 12 d were the boundary points of the change.The amplitude reached 2.345×104 V2,3.923×104 V2 and 61.54 pV2/Hz,98.86 pV2/Hz.The test results have been proven to coincide well with the change rules of the strength of specimens in the process of practical maintenance.