TY - JOUR
T1 - Use of indentation tests to study the influence of confining stress on rock fragmentation by a TBM cutter
AU - Yin, L.J.
AU - Gong, Q.M.
AU - Ma, H.S.
AU - Zhao, J.
AU - Zhao, X. B.
PY - 2014/12/1
Y1 - 2014/12/1
N2 - This paper explores the influence of the confining stress on rock fragmentation under the cutter of tunnel boring machine (TBM) by indentation test. Acoustic emission (AE) system was employed for real-time monitoring the rock fragmentation process during the indentation test. Granite and marble samples were used in the indentation test. The rock fragmentation processes with the different confining stress levels was studied based on the characteristics of force-penetration depth curve and the AE parameters, including AE energy rate, hit counts, amplitude and location of AE events. After the indentation test, the rock samples were cut along the centerline of rock samples and subsequently the crack distribution and the size of crushed zone were measured. The test results showed that the force for crack initiation and crushed zone size increased with increasing confining stress. The cracks tend to propagate to the free surface as the confining stress increases. But for the marble samples, there exists a critical confining stress condition, such that if the confining stress is more than the critical value, the force for crack initiation and crushed zone size decrease dramatically. Moreover, it was found that rock slabbing induced by confining stress had occurred before TBM cutter indentation. Such confining stress condition promotes rock fragmentation.
AB - This paper explores the influence of the confining stress on rock fragmentation under the cutter of tunnel boring machine (TBM) by indentation test. Acoustic emission (AE) system was employed for real-time monitoring the rock fragmentation process during the indentation test. Granite and marble samples were used in the indentation test. The rock fragmentation processes with the different confining stress levels was studied based on the characteristics of force-penetration depth curve and the AE parameters, including AE energy rate, hit counts, amplitude and location of AE events. After the indentation test, the rock samples were cut along the centerline of rock samples and subsequently the crack distribution and the size of crushed zone were measured. The test results showed that the force for crack initiation and crushed zone size increased with increasing confining stress. The cracks tend to propagate to the free surface as the confining stress increases. But for the marble samples, there exists a critical confining stress condition, such that if the confining stress is more than the critical value, the force for crack initiation and crushed zone size decrease dramatically. Moreover, it was found that rock slabbing induced by confining stress had occurred before TBM cutter indentation. Such confining stress condition promotes rock fragmentation.
KW - Confining stress
KW - Crack initiation and propagation
KW - Indentation test
KW - Tunnel boring machine (TBM)
UR - http://www.scopus.com/inward/record.url?scp=84908393897&partnerID=8YFLogxK
U2 - 10.1016/j.ijrmms.2014.07.022
DO - 10.1016/j.ijrmms.2014.07.022
M3 - Article
AN - SCOPUS:84908393897
VL - 72
SP - 261
EP - 276
JO - International Journal of Rock Mechanics and Mining Sciences
JF - International Journal of Rock Mechanics and Mining Sciences
SN - 1365-1609
ER -