In fact, building a shield machine is not as difficult as many might think, because the world's first shield machine was born in the late 18th century, two hundred years ago. It relied on manual digging, and compared to today's large mechanized shield machines, it didn't have many high-tech components.
Though early shield machines were structurally simple with no high-tech elements, they are the ancestors of today's modern shield machines and their principles are derived from them.
Chen Xin wants to build a shield machine himself. Unless he starts from scratch with a novel design approach, he cannot bypass the foundational principles laid over two hundred years ago.
The principle of a shield machine is not complex. The main idea is that while the tunneling machine is advancing, it constructs a "shield" to protect the tunnel and prevent collapses — it excavates and repairs simultaneously.
