Comprehensive consideration of user-control variables for drilling resistance measurement system and estimation of uniaxial compressive strength of sandstone and clay brick

Abstract

The Drilling Resistance Measurement System (DRMS) test is a minimally destructive technique suitable for the field assessment of the mechanical properties (such as uniaxial compressive strength) of masonry relic surfaces within a certain depth range, but the test results of drilling resistance are prone to be affected by user-control variables. Currently, there is no unified test specification or standard for the manual of user-control variables. To ensure that the drilling resistance test results are comparable under different user-control variables, in this study, sandstone and clay brick were used as the research objects to investigate and analyse the effects of different user-control variables on the drilling resistance test results. The results show that the drilling resistance had a linear positive correlation with the penetration rate, drill bit diameter, and drill bit wear but a linear negative correlation with the revolution speed; the drilling resistance of sandstone had a linear negative correlation with the water content, while the opposite was observed for clay bricks. The drilling resistance mean values at different drilling depth ranges were compared, and a method for calculating the drilling resistance mean value was proposed. Moreover, the uniaxial compressive strengths of the sandstone and clay brick were evaluated by drilling resistance. Wider spreading of the DRMS can be achieved by recording user-control variables in detail if the correlation expressed in this paper is further tested.