A "Deep" Dive: American Youth Get an Up-Close Look at a "Great Power Heavyweight"
Recently, more than 20 young Americans and veteran engineers visited Zhengzhou, Henan, to get an up-close look at a "great power heavyweight" — the tunnel boring machine (TBM). In the general assembly workshop of China Railway Hi-Tech Industry Corporation under China Railway Group Limited, two TBMs, each as tall as a two-story building, stand parked. The machine's cutting face (cutterhead) is covered with rollers and scraper blades. Unlike the common sharp, slender electric drill bits, the TBM's "drill bit" consists of blunt, thick cylindrical cutters designed to reduce damage to the cutting head from hard rock. During excavation, the cutters grind through the rock and soil, and the scrapers then scrape away the debris, which is carried out of the tunnel on a conveyor belt. At the same time, the machine reinforces the tunnel walls.
2024-06-11