Identification of geological interfaces from drilling process monitoring in ground investigation

Abstract

The method of using a hydraulic rotary drilling machine to explore conditions of subsurface is widely applied in ground investigation. A new technique, Drilling Process Monitor (DPM) has been recently developed to automatically and continuously monitor the full drilling process. From analyzing DPM data, the pure drilling curve versus time can be obtained. The drilling rate as an index for characterizing the ground condition can be calculated with confidence. It is observed that the drilling rate is variable with depth and the variation is consistent with the change of geomaterial properties along the drillhole depth. Thus, the DPM data are capable of determining the positions of geological interfaces. A case study is given in the paper to illustrate how to find and locate the interfaces according to the DPM data. Comparisons are also made between the DPM analyzed results and the recovered core samples. © 2008 Taylor & Francis Group.