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What is the explosive nature of rock? What are the classification methods for rock explosiveness?
Rock blastability refers to the difficulty of rock blasting. Commonly used in the country is Platts classification. That is, it is determined by the uniaxial compressive strength of the rock.
f=R/100
In the formula:
R-rock uniaxial compressive strength, kg/cm 2 . (Note: R units are used by the old system.)
Or f=R/10
In the formula:
R-rock uniaxial compressive strength, MPa (1 kg / cm 2 = 0.1 MPa).
The solid grade of Platts rock captures the main property of rock resistance to various failure modes, and it is widely used in mining engineering by using a simple and clear rock solidity coefficient to express this commonality. However, the concept of rock solidity is too general and can only be used as a general classification, which does not complete the physical essence reflecting the rock fragmentation process.
Northeastern University comprehensively considers the blasting funnel test and acoustic wave test under the standard conditions of blasting materials, processes and parameters. According to the volume of the blasting funnel, large block rate, small block rate, average pass rate and wave impedance, etc., use mathematical data. Statistical multivariate regression analysis and electronic computer processing, the formula of rock explosive index F is obtained, and is divided into five levels according to the size of F.
In the formula:
F-rock flammability index;
V-blasting funnel volume, m 3 ;
K d - large block rate, %;
K x - small block rate, %;
K p - average pass rate, %;
PC-rock wave impedance, (g/cm 2 s) × 10 5 .
This method can be measured on site, but the work intensity is large, and it has certain randomness, and the calculation is complex and needs to be improved.
There are also the former Soviet Union A.Φ. Sukhanov rock classification method, Hanukayev rock classification method, and the Livingston blasting funnel rock classification method in the United States.