混凝土构件与灌注桩超声波衰减成像的效果分析

Effect Analysis of Ultrasonic Attenuation Tomography for Concrete Member and Cast-in-place Piles

采用迭代Tikhonov正则化算法对一带有蜂窝缺陷体混凝土构件模型与一带有相同缺陷灌注桩模型进行了超声波衰减图像重建,并与速度成像相比较,其结果表明:灌注桩衰减成像可清晰显示出缺陷体的位置与形态,混凝土构件成像效果较差,两模型速度成像对缺陷体均有较好的反映。而后又对一桥梁工程灌注桩进行了衰减图像重建,所得图像与速度成像吻合较好,从而证明了该算法的有效性。在实际工程检测中,对灌注桩宜进行速度与衰减系数双参数成像,对混凝土构件则只宜进行速度成像。

Iterated Tikhonov regularization algorithm is used to calculate ultrasonic attenuation tomography for a concrete member model with a honeycomb defect and a cast-in-place pile model with the same defect. The reconstruction images are also compared with the velocity images. The results indicate that the reconstruction image for the cast-in-place pile clearly shows the position and shape of the defect but the effect of reconstruction image for the concrete member is poor. The velocity images for the two models both clearly show the shape of defects. Furthermore, the algorithm is used on the attenuation image reconstruction for a cast-in-place pile of the bridge engineering. The reconstruction image relatively coincided with velocity image. It is proved that iterated Tikhonov regularization is an effective attenuation imaging algorithm for cast-in-place piles. A cast-in-place pile should carry out the dual-parameter tomography in practical engineering testing but the concrete member can only carry out velocity image.