Kneel and beg! Empirical formulas for RQD in geology?

RQD is an internationally used method to identify the quality of rock engineering, which uses the modified core taking rate of borehole to evaluate the quality of rock. That is, the diamond drill bit with a diameter of 75mm and the double-layer core pipe are used to drill in the rock, and the core is continuously drilled, and the ratio of the sum of the length of the core section with a length greater than 10cm to the footage of the core is expressed as a percentage. Obviously, RQD mainly reflects the degree of rock integrity, i.e. the degree to which fractures develop in the strata of the section.

According to the level of RQD value, the rock mass is divided into five categories:

Category RQD (%) Rock mass.

1 90 100 Good.

2 75 90 is better.

3 50 75 General.

4 25 50 Poor.

5 < 25 is poor.

The calculation formula is RQD=LP (cumulative length of core faults greater than 10cm) LT (total core length) 100

Rock Quality Designation (RQD), a concept proposed by Deere in 1964, is a method used to express the goodness of rock mass. RQD is determined based on the modified core take rate, which is the ratio of the total length of the core directly obtained in the borehole to the total length of the broken core and the weak mud inclusion, and then to the total length of the borehole. The method stipulates that when calculating core lengths, only hard and intact cores larger than 10 cm are counted.

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1. Rock quality index.

Chinese Name: Rock Quality Designation English Name: Rock Quality Designation Definition:

The ratio of the total length of the core fault block with a length greater than 10cm to the footage of each drill footage with a diameter of 75mm diamond drill bit is expressed as a percentage. In order to characterize the degree of development of rock joints and fractures. Applied Disciplines.

2. Rock quality index.

3. Rock quality indicator.

4. Indicators.

It is a rock quality index, a general method to identify the quality of rock engineering. The corrected core taking rate of borehole skin was used to evaluate the quality of rock. Generally, a diamond drill bit with a diameter of 75mm and a double-layer core tube are used to drill in the rock, continuous coring, and the ratio of the sum of the length of the core section with a length greater than 10cm to the length of the core is expressed as a percentage of the wheel.

It mainly reflects the degree of integrity of the rock, that is, the degree of development of fractures in the strata of the section.

(RQD): Rock quality index, drilled in the rock with a diamond drill bit with a diameter of 75mm and a double-layer core tube, continuous coring, and the ratio of the sum of the length of the core section with a length greater than 10cm to the footage of the core, expressed as a percentage.

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REC % is the adoption rate, and RQD is obviously the basic quality grade of the rock mass.