Abstract
The concept of tunnel boring machine (TBM) disc cutter rock breaking coupled with high-pressure water jets has been proposed to overcome the difficulties that occur when TBMs encounter extremely hard rocks. Thus, to meet actual engineering requirements for the TBM construction of tunnels as part of the Wan’anxi water diversion project in Longyan City (Fujian Province, China), experiments were conducted on high-pressure water jet-assisted TBM disc cutter rock breaking. By varying kerf depth and width under different water jet parameters and performing disc cutter rock breaking tests on rock surfaces with no kerf, single kerf, and double kerfs, the effects of different kerf depths on the disc cutter rock breaking process, load, and efficiency were examined. The test results showed that high-pressure water jets can generate the regular kerfs required for the coupled disc cutter rock breaking of granite. Employing the coupled rock breaking method also resulted in a decrease in specific energy and an approximately 40% decrease in the normal force of the disc cutter, thereby significantly improving rock breaking efficiency. These results provide key technical parameters for the design and manufacture of high-pressure water jet-assisted rock-breaking TBMs and serves as a reference for similar processes.
Highlights
Tunnel boring machines (TBMs) are tunnel engineering construction machines that use disc cutters on a rotating disc cutter to cut rocks by extrusion and shearing, acting on the entire cross-section of the tunnel at any given time
This paper presents experimental research on TBM disc cutter rock breaking coupled with high-pressure water jets with a focus on the hard granite strata at the site of the Wan’anxi water diversion project in Longyan City (Fujian Province, China)
This research was guided by the actual rock breaking needs of the TBM employed in the Longyan water diversion project
Summary
Tunnel boring machines (TBMs) are tunnel engineering construction machines that use disc cutters on a rotating disc cutter to cut rocks by extrusion and shearing, acting on the entire cross-section of the tunnel at any given time. The rock breaking performance indicators included kerf depth and width; during the tests, the flow rate and the power of a single nozzle under different water jet pressures and nozzle diameters were recorded to provide a basis for the final equipment parameter selection.
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