Pure Principle Feeds on Instagram: "🚇 How does the world’s biggest tunnel boring machine actually work? 🤔 Meet the TBM (Tunnel Boring Machine) — a giant metal beast that chews through rock using a rotating cutter head the size of a house! ⚙️ As it drills forward, it builds the tunnel walls behind it — sealing, reinforcing, and digging all at once. 💪 Precision, pressure, and pure power — all underground. 👉 Follow @pureprinciplefeeds for more jaw-dropping engineering wonders! #TunnelBoringMach