RQD was proposed by Deere (1964) as a measure of the quality of borehole core. The RQD is defined as the ratio (in percentage) of the total length of sound core pieces that is 0.1 m (4 inch) or longer to the length of the core run. Besides the direct method for deter-mining RQD from coring, different indirect methods are also

LIMITATIONS ON RQD • Does not account for the existence, thickness and strength characteristics of joint coating or filling materialcharacteristics of joint coating or filling material • Does not account for joint roughness or interlock • Can be significantly influenced by angle of boring • “Sound” rock can be veryyj subjective • Core may deteriorate between drilling and logging

Mar 1, 2016 · Since in many cases rock quality designation (RQD) is the only rock mass classification index available, this paper outlines the key aspects on determination of RQD and...

The RQD is an index of rock quality in which a modified core recovery per centage is obtained by counting only pieces of sound core 4-in. (100 mm) or greater in length of NX size or larger core diameters.

The RQD can provide an indication of rock quality in quarries for concrete aggregate, rockfill, or large riprap. 5.3 The RQD has been widely used as a warning indicator of low-quality rock zones that may need greater scrutiny or require additional borings or other investigational work. 5.4 The RQD is a basic component of many rock mass

3.1.2 Rock Quality Designation (RQD) Rock quality designation (RQD) should be determined as specified in IS 11315 (part 11). The details ofrating are given in Annex B (Item Il), Where the rock cores are not available, RQD can be determined with the helpoffollowing formula: RQD = 115-3.3Jv = 100 for J; <4.5 where J, =numberofjoints per metre cube.

The Rock Quality Designation index (RQD ) was developed by Deere (Deere et al 1967) to provide a quantitative estimate of rock mass quality from drill core logs.

The RQD index is an index of rock quality in that problematic rock that is highly weathered, soft, fractured, shcarcd, and jointed is counted against the rock mass.

The RQD is a modified per cent core recovery which incorporates only sound pieces of rock core that are 100 mm or greater in length along core axis. RQD = {(S Xi) / (total length of core, L)} x 100%. Xi = core length 100 mm L = length of core recovered (1.5m if barrel is full)

El Shinawi, abdelaziz (no date) “Rock Quality Designation (RQD.” A measure of rock mass integrity based on the condition of core samples. This standard is issued under the fixed designation D6032/D6032M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision.