基于振动超声调制的混凝土裂缝行为表征试验研究

Experimental Study on Concrete Crack Behavior Characterization Based on Vibro-acoustic Modulation Method

基于振动-超声调制方法,利用低频振动和超声表面波对加载—卸载循环下的混凝土板梁纯弯段受拉区开展试验研究.提出采用调制旁频谐波能量值与两基波能量值乘积之比作为调制指标参数,用来表征混凝土裂缝在加载和卸载过程中开启和闭合过程中的非线性超声调制特征.结果表明:随着荷载的增大,裂缝逐步张开,调制指标参数表现出增大趋势;但随着裂缝的张开扩大,调制指标参数逐步下降.试验结果揭示了在不同荷载作用下裂缝的开合程度对调制指标参数的影响.高阶谐波两侧产生的调制旁频可作为表征裂缝张开和闭合活动的特征参数.

Based on the vibration-ultrasonic modulation method,a preliminary theoretical and experimental study was carried out on the tension zone of pure bending section of concrete slab beam under loading-unloading cycle by using low-frequency vibration and ultrasonic surface wave.The ratio of the modulated side frequency harmonic energy value and the product of two fundamental energy values was used as the modulation index parameter to characterize the nonlinear ultrasonic modulation characteristics of concrete cracks during the opening and closing process during loading and unloading.The results show that with the increase of load,the cracks gradually open and the modul ation index parameters show an increasing trend.However,with the opening and expansion of cracks,the modulation index parameters gradually decrease.The test results reveal the influence of crack opening and closing degree on modulation index parameters under different loads.The modulation side frequency generated on both sides of high-order harmonics can be used as a characteristic parameter to characterize the opening and closing activities of cracks.