The Influence of Confining Stresses on Rock Fragmentation, Thrust Force, and Penetration Energy in Sandstone Indentation Tests Using Disc Cutters

Published on Mar 31, 2021in Advances in Civil Engineering1.924
· DOI :10.1155/2021/5541538
Gaofeng Wang2
Estimated H-index: 2
(CUMT: China University of Mining and Technology),
Ting Ren27
Estimated H-index: 27
(University UCINF),
Gaolei Zhu1
Estimated H-index: 1
(CUMT: China University of Mining and Technology)
Sources
Abstract
Hard rock Tunnel Boring Machines (TBMs) engaging disc cutters as cutting tools have been employed in considerable underground coal mines to accommodate the requirement of more stone drivage as operations are going deeper. This study conducted a set of disc cutter indentation tests to explore the influence of confining stresses on rock fragmentation, thrust force, and penetration energy on sandstone, which is commonly encountered in underground coal mines. The test results show that there exists a critical confining stress, under which the maximum thrust force and penetration energy keep increasing with confining stress mounting while the maximum thrust force and penetration energy will decrease or flatten if it is surpassed. By combining with previous studies and comparing the critical confining stress values to the rock mechanical properties’ values, the critical value is most likely to be of cohesion. For subsurface rock fragmentation, the Constant Cross Section (CCS) disc cutter indentation has denser cracks and their orientations are more lateral than those under the V shape one; the V shape disc cutter indentation is less sensitive to confining stresses, with no notable increase of crack number and crack reorientation with increasing confinement. Thus, the CCS disc cutter is more favorable than the V shape one from the perspective of rock fragmentation under confining stresses.
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At present, the constant cross section (CCS) disc cutter with flat edge is widely used in TBM tunnelling project. But the problem of serious wear and low rock breaking efficiency appeared when the CCS disc cutter was driven into the high abrasive stratum. The disc cutter with small edge angle is designed in order to enhance the service life of the disc cutter in this paper. The simulation of the two kinds of cutter rings rock breaking were done based on the theoretical analysis used the theoreti...
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Cited By1
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#1Chuyuan Cao (XTU: Xiangtan University)
#2Kui Zhang (XTU: Xiangtan University)
Cutter performance evaluation is important for shield TBM during the design and refurbishment stage. To face the challenges of choosing the proper cutters for tunneling in complex condition, according to the concept of parameter profile analysis, a systematic evaluation method was proposed. In this novel method, by comparing with their expected best value and the corresponding unacceptable limit, all of the selected performance parameters can be synthesized to assess the proximity of the overall...
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