This chapter introduces Volume 31 of the Engineering Geology Special Publications (EGSP) series, and includes the Working Party membership, the remit of the Working Party and the structure of the book, including a summary of the contents. Also included are key terms and concepts that are developed within the EGSP.
This paper contains the author's personal views on how and why construction problems and disputes related to unforeseen ground conditions occur. The ‘how and why’ relate to: (i) a common contaminated land focus in the initial project desk studies that is then not updated as projects develop; (ii) a focus on known factual data; and (iii) a lack of focus on the conceptual data that inform what construction hazards might be present in gaps between observed data points. Potential technical and commercial mitigations for these shortcomings are suggested. These include structuring geotechnical deliverables around the concepts set out in the IAEG Commission 25 on engineering ground models: increased training of ground engineering practitioners on the contractual context of their work and on increasing the self-awareness of what the engineering geological input into projects should be and the competencies required to produce that input.
Chalk is known to have a potential risk for natural cavities, thus developing an accurate geological model and documenting the location and nature of these geohazards is important to infrastructure projects. Building the geological model requires investigation of the geomorphology, engineering geology, geological history and behaviour of geological materials (soil and rock mass). The identification of dissolution features is based on geomorphological mapping, LiDAR surveys, intrusive ground investigation and surface geophysics, with the aim of understanding the geological environment and the associated risk. Peter Fookes’ geological model approach is illustrated with a case study from High Speed Two (HS2) railway line in the North Chilterns Area section. This section includes cuttings, embankments and viaducts that will be designed and constructed in chalk formations in an area where the risk of dissolution features is moderate to high. These features appear either as infilled features near the base of cuttings and embankments, or as void or infilled features, that are present immediately below the toe of foundation piles or along their shaft. The exposed ground conditions during construction of the cutting are presented and compared with the predicted geological model. In brief, the model could not predict accurately the shape of the surface between the chalk and the clay infill material, and the excavation revealed a geometry for the infilled dissolution features in the chalk with irregular patterns that would have not been possible to be predict accurately.
This introduction provides background to the development of engineering geology as a recognized branch of applied geology from antiquity through to the present day. In the development of the subject in the modern era, Professor Peter Fookes had a leading role in the UK and this is identified and celebrated. Specifically, the legacy Peter Fookes has left to engineering geology in the fields of ground models, geomaterials and geomorphology is briefly reviewed as this forms the focus of the book.
The implications of sulfide and sulfate minerals on landforms and foundations vary significantly between temperate, arid and equatorial zones. Sulfur minerals, especially pyrite and gypsum, underlie significant engineering problems due to volumetric and mineralogical changes that occur following exposure to surface weathering environments. Whilst pyrite is stable under the anoxic reducing conditions in which it forms, exposure to oxygenated, damp environmental conditions result in rapid oxidation that produces chemically aggressive acidic, sulfate-rich solutions. If carbonates or cementitious material are present, potentially expansive selenite–gypsum is likely to be formed. In dry arid environments, these processes will occur more slowly, but their effects are often observed as dramatic slope failures. Dry environments are also conducive to the preservation of sulfate minerals such as gypsum and anhydrite in the ground. However, these minerals are liable to undergo dissolution and volume changes when disturbed by construction that may also create conditions that are chemically aggressive for concrete and other materials. The possibility of long-term impacts of weathering and changes brought about by the engineering works must be considered in ground investigation and geomaterials assessments, accounted for in the ground model, and addressed in the proposed design and method of construction. The intention of this paper is to outline some of the implications of sulfur minerals in geomaterials, provide guidance on the identification of potential problems in construction and landform evaluations, and suggest ways of avoiding difficulties.
This volume is about the work of Professor Peter G. Fookes and the legacy he has left to the present and future generations of engineering geologists. In this endpiece the nature of this legacy is reflected through the experiences of scientists and engineers who worked with him, his emphasis on case studies in his published work, and how Peter's ground model concept espoused in his 1997 Glossop Lecture can be used to accommodate landscape changes and changes to ground conditions that may occur during the lifetime of a project.
This paper presents a technique for the visualization and semi-quantification of various ground engineering criteria, in the form of a spider graph. There are currently few techniques for effectively presenting multiple ground engineering and engineering complexity criteria in a single graphic. The technique described proposes a tool that can do so for technical and non-technical audiences alike. The input criteria can be adapted to suit any project in soil, rock or a combination of both. The methodology and example presented is for a current Jacobs’ rock engineering project. The geotechnical parameters used include unconfined compressive strength, Geological Strength Index, in situ stress and groundwater head. Engineering complexity is also considered and an additional criterion to allow for significant influences not accounted for in the other criteria. The input criteria must be set at the beginning of the project to ensure that comparisons can be made both between terrains (areas with similar ground engineering characteristics) and throughout the life cycle of a project. The tool aims to communicate ground conditions and potential ‘ground risk’ with the usefulness of the tool being its simplicity and adaptability to meet the project needs at all stages of the project. A preliminary version of an ‘ app ’ is available to trial the tool.
This paper contains the author's personal views on how and why construction problems and disputes related to unforeseen ground conditions occur. The ‘how and why’ relate to i) a common contaminated land focus in initial project desk studies are then not updated as projects develop ii) A focus on known factual data and iii) a lack of focus on the conceptual data that informs what construction hazards might be present in gaps between observed data points. Potential technical and commercial mitigations for these shortcomings are suggested. These include structuring geotechnical deliverables around the concepts set out in the IAEG Commission on Engineering Ground models (EGMs); increased training of ground engineering practitioners on the contractual context of their work and on increasing the self-awareness of what Engineering Geological input into projects should be and the competencies required to produce that input.
This chapter addresses the significant challenges encountered in constructing engineering works below groundwater level, particularly in deep subsurface projects such as shafts and tunnels. It explores how groundwater interaction can lead to decreased water levels, surface settlement and potentially severe inflows that disrupt excavation progress and destabilize the construction site. These issues may also cause environmental damage and affect nearby structures. The chapter outlines two primary strategies for groundwater control. The first strategy involves preventing water ingress by enhancing ground impermeability or installing physical barriers such as diaphragm walls. Alternatively, adjusting groundwater gradients using techniques such as earth pressure balance machines during tunnel excavation is discussed. The second strategy focuses on actively lowering water levels through pumping or passive drainage to manage groundwater effectively. The requirements for long-term weathertightness of underground structures and possible strategies are also discussed.
Theories for groundwater flow provide the means for quantitively predicting the movement, pressure, temperature and chemical quality of groundwater with time. The raw data these theories require to achieve a prediction are as important as the theories themselves. Engineering geologists must consider the ground and its water for any site to identify what data are required for the safe construction and future functionality of the project in hand. When making such decisions it is of immense value to know what these theories can deliver and how they use the data selected to make their predictions. This chapter describes and explains the basic concepts behind commonly used theories for groundwater flow, to provide a sound basis for deciding what data their predictions require for assuring the construction and working life of a project, and for assessing the reliability of predictions they make based on the data they have used.
This publication provides a state-of-the-art review for managing the risks associated with groundwater during design and construction. The book embraces practical applications to address groundwater problems drawn from the world-wide experience of subject matter experts. Groundwater concepts, hazards and risks and mitigation strategies for surface and subsurface engineering applications are given, with comprehensive case studies.
An Observational Model is a conceptual framework, with quantitative elements, for the behaviour of the ground and groundwater system, within which calculations and performance assessments may be made. It is built up by observations from a variety of sources, including the literature and existing information through a desk study, an intrusive ground investigation, in situ and laboratory tests, and monitoring data. There is a particular emphasis on the topology, stratigraphy, groundwater boundary conditions and groundwater flow properties including hydraulic conductivity (Darcy permeability), inhomogeneity and anisotropy. The aim of this chapter is to describe and discuss the site investigations and associated laboratory testing, pumping tests/trials and long-term monitoring that contribute to building an observational groundwater model. It encompasses methods, instruments, techniques; the design of site investigations, pumping tests/trials; and monitoring strategies, interpretation and reporting. A particular objective is to critically appraise methods for the assessment of hydraulic conductivity and anisotropy.
A framework for groundwater risk management introduces the use of models to manage groundwater risk. Parry et al. (2014) in the publication ‘Engineering Geological Models – an introduction: IAEG Commission 25’, subsequently updated in Baynes et al. (2022), introduce three fundamental geological models: the Conceptual Engineering Geological Model, the Observational Engineering Geological Model and the Analytical Model. The models are progressively developed and iterated throughout the stages of a project, reducing uncertainty by increasing the understanding of both the ground and its engineering significance.
Problems caused by groundwater – discusses a wide range of groundwater problems experienced by engineering works and examines some of the geotechnical mechanisms behind such problems, and some of their potential solutions. All in-ground engineering works interact with groundwater, either in terms of the effect of groundwater inflows, groundwater pressures or the change in behaviour of geological materials due to groundwater effects. For most construction projects, the groundwater itself and its effects are most commonly an impediment to construction and are thus viewed as ‘problems’. This Chapter explores some of these problems by means of examples from literature and from the Authors considerable experience, with many illustrated by figures.
Groundwater is more than just a theoretical problem for construction projects and a wide range of engineering schemes can encounter obstacles related to groundwater conditions. However, appropriate actions are required at all stages of construction projects, including planning, investigation, design, construction, maintenance and decommissioning. So whilst the range of available techniques and their application are described in other chapters, Chapter 9 – Managing Groundwater in Practice - describes the key elements of the process of preparing for the management of groundwater in construction practice, including planning, design and regulatory matters.
Examples of problems caused by groundwater, and methods of groundwater control are discussed in other chapters of this book. This Chapter deals with how the risks associated with potential groundwater problems may be managed in practice, in certain engineering situations relating to surface works. For surface works, the problems caused by groundwater can be overcome in a variety of ways. Dealing directly with the groundwater itself (‘groundwater control’) is often an efficient way of addressing the problem and is, in many cases, essential. However, this is not always the case. For some structures, modifications to the permanent works can avoid the need for a groundwater control solution that involves groundwater pumping, monitoring or maintenance in perpetuity. Some design guidance documents require designers to assume that groundwater is at ground level unless there is better information. In this case, the optimal solution may include investment in a more comprehensive investigation to obtain the necessary data to challenge this onerous assumption. In considering the management of groundwater, it is also important to manage surface waters, as these can quickly become sources of groundwater, affecting the groundwater regime.
This chapter explains the requirement for conceptual models to support decision making for addressing groundwater in design and construction. It defines conceptual models and approaches to their formulation, presentation, communication and reporting. The chapter provides useful sign posting to a range of data sources that are available to practitioners. The second half of the chapter presents a broad range of example conceptual models that represent different climatic and environmental scenarios.
This chapter contains nine relevant case studies demonstrating the management of groundwater risk in engineering geological situations. There are scenarios including modelling, risk management, and both surface and subsurface works. The chapter includes relevant case studies demonstrating the management of groundwater risk in engineering geological situations. The case studies are self-contained and relate to the chapter topics included in this publication, as illustrated in Table 12.1 .
Micropalaeontology is a core component of biostratigraphy and, as a subject, is constantly in use for the solution of stratigraphical and palaeoenvironmental problems. The application to the field of engineering geology, and specifically site investigation, is probably less well appreciated despite its role in the construction of two major infrastructure projects in SE England: namely the Channel Tunnel and the Thames Barrier.
The construction of the A21 Sevenoaks bypass in Kent is a seminal case study in engineering geology. In 1965 during the earthworks for the road, major slope failures occurred presenting a significant setback to the programme. No slope stability issues were foreseen before the groundworks commenced. Post-failure forensic investigations revealed multiple shear surfaces within lobe-like landforms that dissected the original route alignment. At that time, these landforms were not recognized, and their problematic nature not fully understood. Similarly, the Maidstone district has long been described as an area of relict periglacial landforms, specifically cambering and associated gulls, and valley bulge. This chapter presents key case studies, which detail the nature of the relict periglacial landsystem that gave rise to the encountered geohazards and demonstrates the advances in ground model assessment offered by airborne LiDAR (Light Detection and Ranging; laser scanning) datasets for engineering geomorphology. High-resolution digital elevation models derived from the LiDAR imagery (that became available for the first time in 2019) can be utilized to interpret and visualize the on-ground geomorphology. The available LiDAR imagery is described, and examples of their use presented from these classic case study sites.
