A Novel Quantitative Detection of Sleeve Grouting Compactness Based on Ultrasonic Time-Frequency Dual-Domain Analysis

Quantitative detection of sleeve grouting compactness is a technical challenge in civil engineering testing. This study explores a novel quantitative detection method based on ultrasonic time-frequency dual-domain analysis. It establishes a mapping relationship between sleeve grouting compactness and characteristic parameters. First, this study made samples with gradient defects for two types of grouting sleeves, G18 and G20. These included four cases: 2D, 4D, 6D defects (where D is the diameter of the grouting sleeve), and no-defect. Then, an ultrasonic input/output data acquisition system was established. Three-dimensional sound field distribution data were obtained through an orthogonal detection layout and pulse reflection principles. Finally, a novel quantification detection with a comprehensive defect index (DI) was established by comprehensively considering eight feature parameters, such as time-frequency domain Kurtosis factor (KU), Skewness factor (SK), Form factor (FF), Crest factor (CF), Impulse factor (IF), Clearance factor (CLF), Wavelet packet energy entropy (WPEE), and Hilbert energy peak (HEP). Construct a DI index by quantifying the difference between defect signals and defect free signals in the time-frequency domain. Experimental results show that, under no-defect conditions, the values of feature parameters are significantly lower than those under defect conditions. Among these, the KU, FF, CF, WPEE and HEP exhibit strong correlations with grout sleeve compactness. The proposed DI index in both types of grout sleeves showed good universality with a linear fit goodness of 0.847–0.962. However, G20 the larger inner diameter and length of the sleeve result in a more complex medium effect during ultrasonic propagation, making its DI index more sensitive to defects than the G18 sleeve. Therefore, the presented method is effective for quantitative detection and analysis of the compactness of grouting sleeves.