Volume 26, Issue 3 (September 2003)
Development of a Spreadsheet for Modeling SPT Stress Wave Data
The advantages of measuring and correcting for variations of Standard Penetration Test (SPT) stress wave energy are well documented. Despite this fact, geotechnical engineers are often hesitant to measure SPT energy, due to high cost and uncertainty about data quality or the reliability of energy calculation methods. Two spreadsheets that model the propagation of stress waves through simple and safety hammers (and attached rod strings) were developed to address the issue of data quality. This paper describes the development of the spreadsheets, including critical aspects of hammer-anvil interaction that are not well documented in the geotechnical literature. Spreadsheet output is verified by comparison to stress wave data collected under controlled laboratory conditions. The safety hammer spreadsheet is then used to assess the quality of stress wave data collected during an actual field investigation. In all cases, the modeled and measured data are in good-to-excellent agreement.