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| Study on rock breaking and wear of TBM hob in high-strength high-abrasion stratum |
| HONG Kairong1,2
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1. China Railway Tunnel Group Co. Ltd., Guangzhou 511458, Guangdong, China;
2. State Key Laboratory of Shield Machine and Boring Technology, Zhengzhou 450001, Henan, China |
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Abstract For the problems facing by Qinling Tunnel South TBM Project of the Hanjiang-Weihe Water Diversion, such as TBM tunneling difficulty in high-strength high-abrasion stratum and heavy cutter consumption, the tunneling parameters and cutter consumption in the first 2 000 m TBM trial tunneling section were studied to put forth problems with some tunneling parameters, including overlarge thrust, excessive penetration, small rotation speed and over-low torque, which would shorten the service life of the hob and limit TBM tunneling speed. It was found that there were not enough cutters near 43# cutter position of the cutterhead, the areal abrasion resistance was inadequate, slag was not removed off from the cutterhead in time, and the secondary wear of the cutter was serious, which all contributed to heavy cutter consumption too. The high-strength hard rock breaking test by hob indicated that rock could be broken efficiently when the cutter edge spacing ranged from 80 mm to 130 mm, but if the ratio of cutter edge spacing to penetration(S/p)was 25~30, TBM would have a lower rock-breaking specific energy and a higher rock-breaking efficiency. The scaled-down-hob wear test in high-abrasion stratum showed that there existed a critical penetration in rock breaking by hob, at which the mass loss rate would increase sharply. It was also found that using rounded-edge hob could lower the hob wear efficiently. The obtained results could provide reference and basis for design of TBM cutterhead and cutter, and control of tunneling parameter for tunneling in high-strength high-abrasion stratum in Hanjiang-Weihe Water Diversion and other projects.
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Received: 23 April 2018
Published: 22 February 2019
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