Support deformation of gate roadway was monitored at four longwall panels of Kushiro Colliery in order to determine the design criteria for construction of the liner road which had been newly developed instead of advancing tail gate. The mining depth of those panels was 660m below the sea level, and the mining geometries of them were almost similar to each other. All the liner roads were constructed within 7m from ribside and used for return air ways.
The measurement revealed that there was little deformation- of support within 20m behind coal face, but after that the deformation increased with advance of the coal face as shown in Figs. 4, 8, 11 and 15, which was approximated by a piece-wise linear curve with respect to distance from the coal face, Fig. 17. Also the support deformation varied periodically along the liner road as shown in Fig. 5, 9, 12, and 16 so that the predominant wavelength was, for instance, 71, 33 and 14m in a typical panel. The upper half arc of the circular ring support or the arch member of the arch-invert support was not only lowered, but also deformed toward the ribside of the panel, Figs. 6 and 13. Furthermore the uplift of floor was profited by level surveying along the liner road.
The results obtained from measurement, therefore, imply that the support deformation of the liner road may scarecely be affected by caving of the immediate roof just after advance of powered support, but may be dominated by main roof lowering and floor heave accompanied by face advance.
