Experimental study on ultrasonic inspection of grouting soil

The grouting technology is applied widely in geotechnical engineering, such as dam, tunnel, subway, bridge and civil engineering. However, due to grouting work belonging to concealment and underground construction, the quality and safety evaluation of the grouting is still difficult. Ultrasonic inspection has been proved to be an economical and efficient technical measure to evaluate grouting work.This paper mainly discusses Laboratory ultrasonic inspection of grouting soil. Grouting soil is produced by mixing together cement, water, and soil aggregates. To simulate grouting soil, four types of grouting soil samples: silt, sand, clay and grit samples, were manufactured. Grouting soil is produced by mixing together cement, water, and soil aggregates. To simulate grouting soil in dam, four types of grouting soil samples: silt, sand, clay and grit samples, were manufactured. The sample’s water-cement ratio (by weight) is 0.5, 0.75, 1, 1.5, 2 and replacement ratio is 15%, 25%, 35%, 45%, 50%. Ultrasonic wave transmission measurements were conducted on the ultrasonic P- and S-waves with a frequency 50kHz of grouting soil, and soil experiments were used to determine mechanical parameters of grouting soil. Moreover, the experiments data had been deducted by the analysis of mathematical statistic. The analysis of data suggest that the correlation between the compression strength and ultrasonic velocity of grouting soil is exponent function. The correlation coefficient of P-wave velocity and the compression strength is bigger than the correlation coefficient of S-wave velocity and the compression strength. We demonstrate that the water content rate of the grouting soil has great impact on the ultrasonic velocity and the impact varies with soil types. With the increase of the blend ratio, the grouting soil strength has to some extents increased. But for the different cement-water ratio, grouting soil has different grade increase in strength. Finally, the time domain analysis results indicate that the types of grouting soil can be identified by the center frequency of P-wave. The range of the center frequency of the dry samples are as follows: sand samples are mainly distributed over 62~97 kHz, grit samples are over 49 kHz and 59 kHz, silt samples are over 48~55 kHz, slay sample are over 7~19 kHz.