Commission 25’s key objective is to develop Guidelines for the development and application of engineering geological models on projects.

Commission 25 main members

Fred Baynes (Chair)

Steve Parry

Martin Culshaw

Jim Griffiths

Background to the Commission

C25 is one of a number of IAEG Commissions established as a result of wide-ranging discussions following the First Hans Cloos Lecture (Knill 2003) at the 9th IAEG Congress in Durban, South Africa in 2002. Baynes & Rosenbaum (2004) noted that the primary focus of these discussions was the use of models within engineering geology. In particular, do we need guidelines for the preparation of models and how should uncertainty be addressed?

Knill, J. 2003. Core values: the first Hans-Cloos lecture. Bulletin of Engineering Geology and the Environment, 62, 1–34.

Baynes, F. J. & Rosenbaum, M. 2004. Discussion arising from the 1st Hans Cloos Lecture, by John Knill. Bulletin of Engineering Geology and the Environment, 63, 89–90.

C25 was established in March 2009 and Commission members were located around the world. So, discussions were primarily by e-mail. However, meetings of the Commission were held during the 7th Asian Regional Conference of IAEG in Chengdu, China in September 2009, during the 11th IAEG Congress in Auckland, New Zealand in September 2010, during the 11th International Symposium on Landslides and Engineered Slopes in Banff, Canada in June 2012 and during the 12th IAEG Congress in Torino, Italy in September 2014.

Following the Torino meeting, a paper on engineering geological models was published in the Bulletin of Engineering Geology and the Environment:

Parry, S., Baynes, F. J., Culshaw, M. G., Eggers, M., Keaton, J. F., Lentfer, K., Novotny J. & Paul, D. 2014. Engineering geological models: an introduction: IAEG Commission 25. Bulletin of Engineering Geology and the Environment, 73, 689-706. DOI: http:10.1007/s10064-014-0576-x

A further paper was published in 2020 in the Quarterly Journal of Engineering Geology and Hydrogeology:

Baynes, F.J., Parry, S., & Novotny, J., 2020. Engineering geological models, projects, and geotechnical risk. Quarterly Journal of Engineering Geology and Hydrogeology, online first:

Following the IAEG’s 12th Asian Regional Conference in 2019 in Jeju, South Korea, it was decided to prepare a set of Guidelines on the Use of Engineering Geological Models. The Guidelines have been retitled as Guidelines for the Development and Application of Engineering Geological Models on Projects. The Guidelines were developed by four members of the IAEG C25 and represent the consensus views of the Commission’s Working Group. A first draft of the Guidelines was presented at the IAEG’s 3rd European Congress meeting in Athens in October 2021. The Guidelines were subsequently revised following comments received at, and after, the Athens meeting, including a contribution from IAEG C28 – Commission for Reliability Quantification of the Geological Model in Large Civil Engineering Projects and from BECA (New Zealand) on digital models.

A second draft was prepared during the first few months of 2022 and has been edited prior to review and final editing. The final version of the Guidelines should be completed in late 2022.

Upon completion, it is intended that the Guidelines will be freely downloadable from the IAEG website. It is hoped that the Guidelines will be translated into a number of key international languages (see below).

Purpose of Guidelines

The purpose of the Guidelines is to establish best practice based on the application of the technique on actual projects. It is intended that the document will provide succinct, practical, accessible and authoritative advice on the effective use of the engineering geological model (EGM). This will cover a wide range of fields, including civil engineering, mining, geohazard studies, land-use planning and environmental assessment.

The central premise is that an EGM is not simply a 2D or 3D visualisation of a data set, it is a comprehensive knowledge framework for the logical evaluation and interpretation of all the geological conditions and their engineering characteristics that are of significance to a project. Thus, the purpose of the EGM is to support the engineering decisions that are made from project inception to decommissioning.

The EGM has two main components:

Conceptual – based mainly on geological concepts and interpretations with some associated engineering concepts, that is, it uses knowledge that certain geological conditions are likely to have certain engineering characteristics. A visualisation of a conceptual component is shown below. Uncertainty in the conceptual model is due to a lack of knowledge or bias of the model developer.

Observational – based mainly on engineering and geological observations and measurements that is constrained in space by 3D data (xyz) or in space and time by 4D data (xyz plus time). Increasingly, the observational model is developed within a digital environment. Uncertainty in the observational model is due to variability and randomness of the intrinsic properties of the ground.

The Guidelines comprise three parts:

(i) Advisory Clauses for the development of EGMs (Part 1).

(ii) Commentary on the Advisory Clauses (Part 2).

(iii) Examples of EGM applications (Part 3).

The visualisation of the conceptual component of an Engineering Geological Model (EGM) for a pipeline crossing unstable ground affected by mining (after Baynes et al. 2020)

The Guidelines will be aimed at practitioners from around the world involved in projects ranging from investigating single storey dwellings to constructing major pieces of infrastructure. The Guidelines are also relevant to the land-use planning of urban areas prior to construction.

The future

It is hoped that once the Guidelines are completed they can be translated into a number of other languages. It is intended that National Groups will be approached to try to achieve this objective.

As the subject of the Guidelines is evolving quickly, it would be sensible for them to be reviewed every four years so that new developments can be added and improvements made.

Commission 25 would be the obvious group to lead these improvements.

Fred Baynes

Steve Parry

Fred Baynes