ロックボルト支保部における計測

坑道支保の効果に関する原位置計測 (第1報)

抄録

Mining industry is now evaluating the rock bolting as a new suppor method because of its significant advantages: reduced storage and handling requirements, improved ventilation, negligible maintenance and soon. This study has been started to reveal the advantages and disadvantages of the rock bolt support over the conventional arch support and examine its applicability to mines of Kuroko are deposit on the basis of in-situ measurement carried out at Fukazawa mine in Akita.
In this first report, the measuring system and the results at roadway supported by rock bolts are described. The rock bolts were installed in a square grid at 1 m interval, and convergence, radial extension of rock wall and axial force of rock bolt have been measured. Up to this time (200 days after installation), measured values have been continuously increasing, and some are of the considerable amount. For example, convergences are in the order of 50-70mm against the roadway of 3.3m height and 4.5m width. However, rate of increase is descreasing monotonously and no trend of roof fall or wall spalling is observed. Among others, it is most interesting that the results of convergence, extension and axial force follow the semi-log relationship, linear increase of the measured value against log time, except the axial force above its yielding point.