Estimating Some Mechanical Properties Of Rock From In-situ Rebound Values
[A CASE STUDY OF OREKE OPEN PIT QUARRY]

4.1.3    CONVERTED FROM N-TYPE TO L-TYPE DATA
Rn(N)=7.124+1.249 Rn(L)
Therefore (Rn(N)-7.124)/1.249 = Rn(L)
Therefore Rn(L)(Rn(N)-7.124)/1.249 = RL
For location 1  
Rn(L)(Rn(N)-7.124)/1.249
Rn(L) = (45.35-7.124)/1.249 =  
Rn(L)= 30.65
For location 2  
Rn(L) =(Rn(N)-7.124)/1.249
Rn(L) = (44.85-7.124)/1.249 = 30.24
Rn(L)=30.24
For location 3  
Rn(L)(Rn(N)-7.124)/1.249
Rn(L) = (45.35-7.124)/1.249 = 30.24
Rn(L)=30.24
4.1.4    ESTIMATION UNIAXIAL COMPRESSIVE STRENGTH
The uniaxial compressive strength (UCS) value is estimated using chart named after Deere and Miller (1996). The chart relate the Schmidt rebound hardness numbers rock density and uniaxial compressive strength
Figure 4.1 Schmidt (L – types) hammer rebound value chart (UCS) (using rebound value conversion graph)
Location (1)
Rebound value = 45.4
Corrected rebound value = (0.98)
Therefore, 45.4 x 0.98 = 44.49
Bulk density = 23.5KN/m3.
Uniaxial compressive strength (UCS) is now determined from the graph as = 70mpa.
Location (2)
Rebound value = 44.9
Corrected rebound value = (0.98)
Therefore, 44.9 x 0.98 = 44.0
Bulk density = 20.7KN/m3.
Uniaxial compressive strength (UCS) is now determined from the graph as = 55mpa.
Location (3)
Rebound value = 44.9
Corrected rebound value = (0.98)
Therefore, 44.9 x 0.98 = 44.0
Bulk density = 20.7KN/m3.
Uniaxial compressive strength (UCS) is now determined from the graph as = 55mpa.