The Correlation of Strength Properties with Rotary Drill Penetration Rate in Soft and Hard Rock Using Linear Regression Analysis

Abstract

Rock strength properties are important parameter for prediction of penetration rate on different rock types when drilling and boring tools are used in a quarry. The project research was conducted using the field data and rock samples collected from the four locations, (granite), Ilorin (MHQ): (limestone) Ibese (DCI); (limestone), Ewekoro (LEW); and (Calcite), Ikpeshi (FGI). Field analysis, the average bulk density and rebound hardness value of samples from the four location as determined in the laboratory in order to estimate Uniaxial Compressive Strength are 27.01kN/m³, 58.6; 19.3kN/m³, 41.4; 15.78 kN/m³, 21.0; 25.98 kN/m³, 43.2 respectively. The results of Uniaxial Compressive Strength as estimated from the correlation chart between average density and Schmidt hardness value shows that location (MHQ) has average strength value of 256MPa, while location  (DCI) 62.04MPa; while location (LEW) 38.58MPa and location (FGI) 35.2MPa. The point load strength index for location (MHQ) has an average value of 10.67MPa, location (DCI) has 1.66MPa, location (LEW) has an average value of 4.47MPa and location (FGI) has 1.18MPa while the tensile strength as estimated from point load strength index for location (MHQ) is 16.01MPa, while location (DCI) is 2.484, location (LEW) is 6.70MPa and location (FGI) average value of 2.67MPa. The penetration rate as determined from field data show that location (MHQ) has an average penetration rate of 0.87 m/min, location (DCI) has an average penetration rate of 0.71 m/min, while location (LEW) has average penetration rate of 0.49 m/min and location (FGI) has average penetration rate of 0.97 m/min. The results obtained showed that penetration rate highly correlated for Schmidt rebound hardness value, bulk density, Uniaxial Compressive Strength, point load strength, and tensile strength.