Report No. : GEO Report No. 189

Report Title : Evaluation of Application of Drilling Process Monitoring (DPM) Technique for Soil Nailing Works (2006), 42 p. plus 2 Appendices

Author : J.S. Lam & C.K. Siu

Abstract

The University of Hong Kong has developed a technique, viz. Drilling Process Monitoring (DPM), to monitor the drilling process for soil nailing works and have used it to characterize the ground conditions at a number of slopes. In collaboration with the HKU, a trial use of the DPM technique was carried out at a site under the LPM programme.

The objective of the study is to find out the possible roles of the DPM technique in improving the design and construction process of soil nailing works. DPM data from a total of 111 drill holes formed using a rotary percussive down-the-hole drilling machine were collected and studied.

The study found that data analysis and interpretation using manual sorting/filtering was rather labor intensive. Apart from ground condition, penetration rate, being the most important parameter for characterisation of ground condition, also depends on other factors including state and construction of drilling equipment, operator skill, groundwater regime and nail length. Penetration rate from the DPM system/technique at its present state has good potential for crude qualitative assessment of the ground intercepts, especially for inferring rock.

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