10- How to Calculate RQD, TCR & SCR in Rock Core Like a Pro!

Welcome back to Geotech Masters! 🌍 We have learned how to name rocks, describe their color, and measure their geometry. Now, we are entering the final and most important step of rock core logging! In this Episode of our series, "The Geotechnical Engineer's Guide to Rock Classification," we are learning how to turn a messy box of broken stones into highly accurate engineering data! 🏗️ Using the international standard ISO 14689, we will master the calculation of three very famous Fracture Indices: TCR, SCR, and RQD. These three simple numbers tell the complete story of the rock's quality. We keep the language simple, highly visual, and easy to understand so you can calculate these numbers perfectly on your next site visit! 🧠💡 👇 In this video, you will learn: 🔹 Total Core Recovery (TCR): Why do we count absolutely everything that comes out of the drill barrel? Learn how TCR warns us about dangerous underground voids and washed-out soil layers. 🕳️ 🔹 Solid Core Recovery (SCR): We get stricter! Discover why we only count solid, full-diameter rock cylinders to understand the true structural integrity of the rock mass. 🪨 🔹 Rock Quality Designation (RQD) & The 100mm Rule: The most famous index in geotechnical engineering! Learn exactly how to measure 100 millimeters from the center of one break to the center of the next break. 📏 🔹 The Golden Rule of Core Logging: Did the earth break this rock, or did the drilling machine break it? Learn why you must ALWAYS reassemble "mechanical breaks" before measuring RQD. Counting driller mistakes will ruin your data! 🛑 🔹 Fracture Index (If): How to measure the spacing between natural fractures in zones of uniform character to give design engineers a clear picture of the block sizes underground. 🧊 Why is this important? ⚠️ If you get these numbers wrong, the entire design classification can fail. Reporting a low RQD because you accidentally counted a mechanical break could cost your construction project millions of dollars in unnecessary steel supports and concrete! 💸 🔗 Helpful Resources: Check out the course link to download our course notes so you can keep these important calculation formulas handy in your pocket on site! 📱🗺️ ________________________________________ 🔑Keywords 1. Rock Quality Designation RQD 2. Total Core Recovery TCR 3. Solid Core Recovery SCR 4. Geotechnical Core Logging Guide 5. How to Calculate RQD 6. ISO 14689 Rock Classification 7. Fracture Index Geotechnical 8. Civil Engineering Site Investigation 9. Mechanical vs Natural Breaks Core 10. Soil and Rock Mechanics