Drilling process monitoring for mechanical properties of artificial geo-materials and in ground investigation

Abstract

Drilling Process Monitoring (DPM) technique has been developed and investigated at HKU for more than ten years, which can continuously measure and record the full drilling process in real time series while the hole is being drilled. It has been applied to the ground investigation, weathered rocks characterization, slope upgrading, SPT test and so forth. DPM technique includes transducer system and data acquisition system. This technique can be mounted on many types of drilling machines. In drilling process, the drilling bit contacts the drilling material directly, which means the drilling process has a close relation with mechanical properties of drilling material. So the drilling process can be considered as an in-situ test of rock mechanical properties. The major obstacle is that it is not easy to grasp the basic mechanic properties of natural materials. As the physical and mechanical properties of concrete are similar to those of intact rock, it is a suitable material for the purpose of this study and is henceforth termed as artificial geo-materials. Therefore, the main aim of the first part of this study was to investigate the specific relationships between the drilling parameters and mechanical parameters of artificial geo-materials in the drilling process. The second part of this study introduced DPM method in the ground investigation in Tongchuan. The main objective of in-situ DPM tests is to use DPM method to characterize rock stratum along the borehole. Furthermore, from the in-situ DPM tests, the data interpretation criteria have been improved. The detailed elaboration of putting steel wires operation has been summarized, which is the distinctive operation. The detailed comparisons between DPM results and other investigation methods results have been made.