Tunnel and Underground Space 터널과 지하공간 ISSN:1225-1275(Print) 2287-1748(Online)

The wet shotcrete refers to a method in which all materials are mixed and then supplied to the spraying device, compressed air is added to the nozzle, and the spraying speed is improved to spray on the target surface. In order to reproduce the amount of shotcrete used in the wet method in the field and the situation at the laboratory scale, it is essential to control the discharge amount of the equipment. In this study, in order to increase the reproducibility of field conditions at the laboratory scale, a flow control system for shotcrete mortar spraying equipment was developed and applied to the equipment. To verify the developed equipment, a discharge control test using water and mortar was performed. In the developed control system, the discharge was smoothly controlled according to the user input value for the mono pump, but the discharge was not properly controlled according to the input value for the screw pump because of a reducer. When a speed reducer is attached, it is necessary to adjust the operation rate of the screw pump close to the target flow rate by increasing the operation rate of the screw pump while lowering the operation rate of the mono pump.