The fearsome-sounding “Gangtie Jiliang” is designed to do what no machine has ever done before: delve straight down, kilometre after kilometre, into the heart of the Earth. Translated to English as “steel backbone”, Gangtie Jiliang is billed as the world’s first boring machine capable of excavating full-face shafts to depths exceeding 1,000 metres (3,280 feet) in hard rock. Weighing about 500 tonnes and measuring 8.1 metres wide, the machine looks less like mining equipment and more like an...