Experimental Investigation on Anti-blocking Characteristics of Concrete Conveying Hose Using Pneumatic Hammer

Compressed air is often used for transporting wet concrete in underground engineering support due to the advantages of simple system structure and easy cleaning of pipeline. However, it always accompanies the issue of easy blockage of pipes during the transportation of wet concrete. Therefore, a method using the vibration effect of pneumatic hammers was proposed and the anti-blocking test device was developed in this study to prevent the blockage of concrete transport hoses. A series of vibration tests considering the air pressure, the number of pneumatic hammers, and the layout of pneumatic hammers were conducted to reveal the vibration characteristics of pipelines. The results show that as the number of pneumatic hammers increased, the vibration frequency decreased initially and then increased, while the vibration displacement had a trend of increasing first and consequently decreasing. As the supply air pressure gradually increased, the vibration displacement showed a tendency of decrease after the increase. In addition, the layout of the pneumatic hammers affected the vibration characteristic of the transport hose when the remaining variables are held constant. According to the test results, the most appropriate number and layout of vibration sources can be selected at different given air pressure to achieve the optimal anti-blocking effect.