Rock Quality Designation Index (RQD) | Procedure, Classification, Example

The rock quality designation index (or RQD) is a widely used index to describe the quality of rock in rock mass. RQD is the ratio between the sum of the length of core samples that are equal to or greater than 10 cm to the total length of the core run. This video shows how it is done in practice. The measurement starts at 0:01:19 Only two pieces had the length of equal or greater than 10 cm; the other (smaller pieces) were ignored. The total run was 1 m (or 1000 mm). The calculations include two pieces: 190 mm (19cm) + 145 mm (14.5 cm).
RQD=(190+145)/1000=0.335 or 33.5% (Poor quality).
RQD is easy to obtain, and it is used in almost all rock mass qualification systems. For Rock Mass Rating (RMR), watch this video • Rock Mass Rating (RMR)... . To see how to estimate RQD in the field, watch this video on rock wall discontinuity spacing • How To Estimate RQD us...
Using an RQD value, the rock mass can be classified as follows:
RQD Rock mass quality
0- 25% Very poor
25-50% Poor
51-75% Fair
76-90% Good
91-100% Excellent
#geology #experiment #science
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[@gabrieltaiwo4316]

Thank you, sir. So very helpful. NB: m to cm multiply by 100 not 1000. (Total core length/100) cm cancel cm and we take it to %

[@user-uu5mu1fs6d]

If you have pieces less that 10cm due to mechanical fracturing don't you still include them in the RQD?

[@randheerliyanage3800]

Yes, even though it's a mechanical fracture, we still consider it as a sound core piece and include it under RQD

[@andspaces5713]

Do you consider difference between mechanical breaks and natural induced openings on the core when measuring pieces more than 10cm ?

[@randheerliyanage3800]

Mechanical breaks or drilling breaks meet the soundness criteria when calculating RQD

[@seymuridrisov8938]

Sorry but you did not explain why you are calculated 3rd piece as a full for RQD.

[@MrK-tb9qi]

I love these lectures 🇿🇦

[@wendelpereira9998]

Thank you!!! This vídeo its so practical, I need It

[@TheTheglobe]

Why allways must be ≥ 10cm? Its just for curiosity :) tanks!!

[@dixonpeter2864]

I'm a student currently studying Mining Engineering at the University of Liberia. I want learn this course we'll.

[@nanshukyi6046]

How do we know it's drilling induced or natural induced?

[@learnwithjosyvaidyan7938]

I believe that third piece of rock can’t be included in the calculation as it is broken

[@GeoEngineeringandScience]

The piece has the length of more that 10 cm; even though it is split on top, it is still included in the calculation.

[@zeyadatty2668]

Dear Dr. , I appreciate the scientific materials you presented in the videos .
Kindly , If possible to explain the CPT for deep compaction and two to check that required relative denisty has been achieved. If available examples for explaining.

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