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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) dis
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Keir Starmer risks being outflanked by the Tories, left-wingers in the Labour Party have warned – as the governing party accused him of poaching their policies.
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Published February 8, 2021, 9:45 AM
Another historic milestone and remarkable event for the Philippines’ railway sector has been unveiled, and government officials and partners witness the arrival of the Cutter Head of ‘KAUNLARAN’, the first among the six Tunnel Boring Machines (TBMs) intended for use in the partial operability section of the first ever underground railway system of the country.
The Cutter Head is the largest part of the TBM, weighing 74 tons. Its main purpose is to break, cut and grind rocks and soil by rotating its 36-piece disc cutter, composed of 15 pieces of single and 21 pieces of twin Roller Cutter (RC).