The image above represents rock quality designation.

To compute for rock quality designation, two essential parameters are needed and these parameters are **Sum of the Length of Core Pieces > 10cm (S) **and **Total Length Drilled or Core Recovery (L). **

The formula for calculating the rock quality designation:

RQD = 100(^{S} / _{L})

Where:

RQD = Rock Quality Designation

S = Sum of the Length of Core Pieces > 10cm

L = Total Length Drilled or Core Recovery

Let’s solve an example;

Calculate the rock quality designation? Given that the sum of the length of core pieces > 10cm is 20 and the total length drilled or core recovery is 14.

This implies that;

S = Sum of the Length of Core Pieces > 10cm = 20

L = Total Length Drilled or Core Recovery = 14

RQD = 100(^{S} / _{L})

RQD = 100(^{20} / _{14})

RQD = 100(1.428)

RQD = 142.85

Therefore, the **rock quality designation **is **142.85.**

**Calculating the Sum of the Length of Core Pieces > 10cm when the Rock Quality Designation and the Total Length Drilled or Core Recovery is Given.**

S = RQD x L

Where:

S = Sum of the Length of Core Pieces > 10cm

RQD = Rock Quality Designation

L = Total Length Drilled or Core Recovery

Let’s solve an example;

Calculate the sum of the length of core pieces > 10cm? Given that the rock quality designation is 32 and the total length drilled or core recovery is 11.

This implies that;

RQD = Rock Quality Designation = 32

L = Total Length Drilled or Core Recovery = 11

S = RQD x L

S = 32 x 11

S = 352

Therefore, the **sum of the length of core pieces > 10cm **is **352.**

Continue reading How to Calculate and Solve for Rock Density Designation | Rock Mechanics