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Rock Quality Designation (RQD) Field Testing
Field Works Description/ Limitation Photos
The RQD is a modified Purpose
core recovery
Measure of the degree of 3. to obtain not reliable
fractures, joints, and Mackintosh the bearing for deep
discontinuities of rock Probe (MP) capacity foundation
mass or indication and critical
JKR Probe by no. of areas.
blows per
RQD = sum of pieces > 300mm does not
100 mm divided by total give soil
core run description
Table 4 : Rock Quality Description
unable to
penetrate
RQD (%) Description of rock hard stratum
quality or gravel
bed
0 - 25 Very Poor
max depth
25 – 50 Poor
15.0m
50 – 75 Fair
75 – 90 Good
90 - 100 Excellent
Figure 7: Mackintosh Probe (MP) and MP Logs
Figure 6: Rock Quality Designation
12 PUBLIC WORKS DEPARTMENT MALAYSIA GEOTECHNICAL ENGINEERING HANDBOOK 13