Abstract
In order to realize the rapid hard-rock tunneling in a safe, highly effective, and economic manner, the hydraulic drilling impact hard-rock tunneling (HDIHT) technology and method were introduced based on the theories of rock mechanics and hydraulic impact. The key parameters, including drilling radius and impact distance, were researched to reveal the stress behavior during HDIHT process. The Von Mises equivalent stress and its principal stress components were analyzed, and the breaking mechanism of HDIHT was also discussed. The simulation results show that, to ensure the effectiveness of “secondary breaking” caused by drilling hole free surfaces, the impact distance should not exceed 200 mm, and the optimal drilling radius was about 35 mm.
Highlights
Hard-rock rapid tunneling, especially for the rock whose hardness exceeds f10, is a worldwide technical issue, whether for underground tunneling or construction
To verify the feasibility of hydraulic drilling impact hard-rock tunneling (HDIHT) method and explore its impact breaking mechanism, a hydraulic hammer (GT130, Giant hydraulic Tech., China) with 7500 J impact energy was used in the field experiments at Baitaizi township granite stone pit, Jinzhou, Liaoning Province, China, and all the items were conducted at the environmental temperature of −15∘C
As shown in the figure, when hammer impacted hard rock directly, its impact energy would be converted into the compressive wave in the depths of rock at the impact moment, and a broken pit was formed in an instant when impact energy was larger than Ac
Summary
Hard-rock rapid tunneling, especially for the rock whose hardness exceeds f10 (rock Platts ruggedness coefficient), is a worldwide technical issue, whether for underground tunneling or construction. Drill and blast tunneling (DBT) and heavy-duty roadheader are still the main methods for hard-rock tunneling in coal mine. Lots of auxiliary equipment and persons needed at working face, great damage to the surrounding rocks, and overtunneling and insufficient tunneling of final sections are the major problems of DBT method. Heavy-duty roadheader has its disadvantages which are as follows: lower economic cutting hardness (≤f8), nethermore tunneling efficiency, higher cutter consumption rate, and so forth. The hard-rock tunnels (≥f10) are not more than 5 percent of the general amount of annual tunneling, it is still a crucial restriction factor for the highly efficient production and management of coal mine. It is urgent to seek a novel, safe, and highly effective approach (including theories, technology, and equipment) for the hard-rock rapid tunneling, with no explosion
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