Experimental study on predicting rock properties using sound level characteristics along the borehole during drilling

Studying effective methods for obtaining in situ rock mechanics properties in geotechnical engineering is highly significant. The development of digital drilling technology has provided additional approaches for predicting rock mechanical properties. Rock drilling generates noise, which varies depending on the rock type, offering a new perspective for preliminary estimation of rock properties. In this study, a self-established digital drilling test system was utilized to conduct digital drilling tests under different experimental schemes, with real-time monitoring of drilling parameters and changes in borehole sound pressure. The borehole sound pressure time history signal was processed to obtain a frequency domain signal, and the total sound pressure level was calculated, aiming to demonstrate the predictability of rock compressive strength using the characteristics of borehole sound level combined with drilling parameters. The experimental results indicate a strong correlation between borehole sound pressure level, rock compressive strength, and drilling parameters such as drill stem rotation speed, penetration rate, and torque, as revealed by regression analysis. Consequently, sound level measurements during the drilling process can proactively assess rock properties and enhance the advanced measurement techniques in drilling.