R.Q.D در کانون توجه

R.Q.D

گزارشی از مهم‌ترین نکات مربوط به «R.Q.D».

Rock Quality Designation  RQD

RQD was introduced by Deere [5] as a way of correlating natural fracturing intensity with engineering performance of a rock mass. RQD measurements are based on the core run.
Run Lengthlength of coresticks 100mmlongRQDΣ≥=%
However, the ISRM [3] suggest “that RQD values are determined for variable rather than fixed lengths of core run. Values of individual beds, structural domains, weakness zones etc. should therefore be logged separately, so as to indicate any inherent variability, and provide a more accurate picture of the location and width of zones with low or zero RQD values.”
“Material that is obviously weaker than the surrounding rock such as over consolidated gouge is discounted, even if it appears as intact pieces that are 10 cm or more in length.”
“The length of individual core pieces should be assessed along the centre line of the core, so that discontinuities that happen to parallel the drill hole will not unduly penalize the RQD values of an otherwise massive rock.” ([3], p47).
An example of the calculation of RQD is shown in Figure 1.