URL:https://www.researchgate.net/profile/Alexandre-Gomes-2/publication/264971024/figure/fig4/AS:392078128369673@1470490118299/Excavation-of-access-tunnel-under-pipe-roof_Q640.jpg
掲載元:https://www.researchgate.net/figure/Excavation-of-access-tunnel-under-pipe-roof_fig4_264971024