Engineering geological mapping for dam foundations – Examples from recent work

This paper explores the importance of engineering geological mapping of dam foundations to enable the assessment of engineering geology characteristics that influence geotechnical parameters, analysis and design of dam foundation design.

The paper provides examples from recent project work where foundation data is recorded by the engineering geologist using technology such as drone – mounted Light Detection and Ranging (Lidar). This approach improves the spatial accuracy of mapped geological features and aids the engineering geologist in producing geological foundation records for as built records.

The paper also describes the process for identification and description of geological features exposed at the foundation surface and includes a methodology for description of geological features using Australian Standard AS1726 – Geotechnical Site Investigations to assist with the assessment of the origin of each defect and describe the associated engineering properties.

Correct assessment of engineering properties is critical for developing a foundation geotechnical model and assessing the foundation kinematics. Recent project work has demonstrated that detailed engineering geological mapping is essential in developing a comprehensive engineering geological model and geotechnical model as required by ANCOLD (2020) and IAEG/C25 (2022) guidelines.