Experimental and Analytical Study on Optimal Spacing for Hard-Rock Breaking under Double-Indenter Impact

Rock breaking by double hydraulic hammers has a wide application prospect in hard-rock roadway excavation because of its environmental protection and strong rock-breaking ability, but the optimal spacing under double-indenter synchronous impact is not clear. Based on the rock-breaking experimental system under double-indenter synchronous impact established by combining a detachable double-indenter device and Hopkinson pressure bar, the impact tests of three kinds of rocks are carried out, and a theoretical model of specific energy consumption is derived to determine the optimal spacing. The results show that when the indenter spacing is 28 mm, 42 mm, and 14 mm, respectively—that is, when the cross section of the fragmentation crater is in the shape of a “peanut” with a fine middle and two large ends—the concrete, limestone, and sandstone specimens reach the minimum specific energy consumption, which is reduced by 22.55 %, 30.60 %, and 11.85 %, respectively, compared with single-indenter impact. The theoretical model, which explains and verifies the experimental phenomena and results well, can be divided into four zones, and the optimal spacing is in Zone III. The research can be helpful for actual hard-rock tunneling under double hydraulic hammers.

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    • © ASTM International 2023. All rights reserved. This material may not be reproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher.
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  • Publication Date: 2023-11

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  • English

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  • Accession Number: 01892092
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 31 2023 10:11AM