Laboratory comparative tests for geomaterial strengths with drilling process monitoring technique

Abstract

This paper introduces a system for laboratory comparative tests of the drilling process monitoring (DPM) method. It further documents a series of comparative test results on cement grouts with aging days in laboratory. The tests include the diamond bit coring with DPM in cement grout blocks and the conventional uniaxial compression tests on the cylindrical grout cores at the aging time from 3 to 25 days. The preliminary test results clearly demonstrate that the grout coring penetration rates decrease and the grout uniaxial compressive strengths increase with the aging days of the cement grout specimens and that the values of the grout coring penetration rates at any aging days have less variations than those of the grout uniaxial compressive strength. These initial findings may indicate that the coring with DPM has the potential to become a tool for in-situ measurement of the mechanical properties and strength of geomaterials including rock and concrete. Finally, the specific energy during grout drilling is studied to correlate with the grout uniaxial compressive strength. An alternative way to measure the specific energy is proposed and will be further studied. © 2008 Taylor & Francis Group.