It's not just luck or concrete — it's rock mass classification, and the Q-System is one of the most trusted tools for it in mining and tunneling. Developed in 1974, the Q-System helps engineers evaluate the quality of rock masses using 6 key parameters: 1️⃣ RQD – Rock Quality Designation 2️⃣ Jn – Joint set number 3️⃣ Jr – Joint roughness 4️⃣ Ja – Joint alteration 5️⃣ Jw – Water inflow 6️⃣ SRF – Stress reduction factor The result? A numerical Q-value that tells you exactly how strong or weak your ground is — and what support it needs. 🔩 Based on this, you can determine: Type of rock support (e.g., bolts, mesh, shotcrete) Support spacing Tunnel stability Q-System = turning geology into engineering decisions.