鋼アーチ支保部における計測結果とロックボルト支保部との比較

坑道支保の効果に関する原位置計測 (第2報)

抄録

Steel arch sets have been widely used in coal and metal mines for roadway support. However, some of them were recently replaced by rock bolts especially in U.S. coal mines and tunnels with large cross-section. Through the current developments of theory and practice, the rock bolt support can be considered as a compatible alternative for the arch support. Included in this second report are the results of in-situ measurements at the arch supported roadway comparing with those at the bolt supported.
Up to this date (200 days after installation), convergence and radial extension of rock wall at the arch supported roadway are considerably larger than those of the bolt supported roughly by the factor of 1.5 to 2. A temporary conclusion may be that the rock bolting is superior to the arch set. Especially in the very early stage, say, within a few days after installation, rock bolting is favored for its immediate effect, while the effect of arch set is delayed until firm contact of arch set or timber lagging with rock wall is established.
Similar to the case of rock bolt support mentioned in the first report, the convergence and radial extension at arch supported roadway follow the semi-log relationship, linear increase with log time. Interestingly enough, the specimen obtained at the test-site follows the logarithmic creep law. This is remained for future research to combine the semi-log relationships observed at in-situ and laboratory tests.