Benefits of a 3D geological model for major tunnelling works : an example from Farringdon, east-central London, UK

In the design of major construction works, the better the ground conditions are known, the more control there is on the assessment of risks for construction, contract and personnel, and ultimately on final costs. Understanding of the ground conditions is usually expressed as a conceptual ground model that is informed by the results of desk study and of dedicated ground investigation. Using the GSI3D software, a 3D geological model (a model composed of attributed solid volumes, rather than of surfaces) can be constructed that exactly honours geologists’ interpretations of the data. The data are used in their true 3D position. The 3D model of faulted Lambeth Group (Palaeogene) strata in the area of the proposed new Crossrail Farringdon underground station, in central London, has several types of benefit. These include allowing optimum use of available ground investigation data, including third party data, with confidence. The model provides an understanding of the local geological structure that had not been possible using other commonly used methods: in particular, it shows the likely distribution of numerous water-bearing coarse deposits and their faulted offsets, which has potentially significant effects on groundwater control. The model can help to focus ground investigation, constrain design and control ris

A tribute to Professor William Dearman : new small-scale engineering geological maps of the United Kingdom

Professor William Robert (“Bill”) Dearman was the first British Professor of Engineering Geology and a world leader in the development of engineering geological mapping techniques and methodologies, recognised by being awarded the IAEG’s Hans Cloos Medal. The maps described here would not have been completed without his initial ideas and interpretative work. It is a great regret that the maps were not finished in time for him to see them before his death in January 2009. This paper and the maps described in it are, therefore, dedicated to his memory

3D attributed models for addressing environmental and engineering geoscience problems in areas of urban regeneration : a case study in Glasgow, UK

The City of Glasgow is situated on and around the lower floodplain and inner estuary of the River Clyde in the west of Scotland, UK. Glasgow’s urban hinterland once was one of Europe’s leading centres of heavy industry, and of ship building in particular. The industries were originally fed by locally mined coal and ironstone. In common with many European cities, the heavy industries declined and Glasgow was left with a legacy of industrial dereliction, widespread undermining, and extensive vacant and contaminated sites, some the infilled sites of clay pits and sand and gravel workings

The relationships between effective porosity, uniaxial compressive strength and sonic velocity of intact Borrowdale Volcanic Group Core samples from Sellafield

The effective porosity, saturated sonic velocity and saturated uniaxial compressive strength were determined on a large number of Borrowdale Volcanic Group volcaniclastic core samples from three boreholes at Sellafield, Cumbria. The work formed part of the UK Nirex Limited site investigation into whether the Sellafield area could be suitable as a repository for intermediate and low level radioactive waste. Most of the intact samples were of low to very low effective porosity, had a high sonic velocity and were very strong to extremely strong. However, a proportion of values deviated significantly from this. Bivariate analysis showed a negative relationship exists between sonic velocity and effective porosity. The cross plots of these two parameters with uniaxial compressive strength showed a wide range of strength values for samples of low effective porosity and high sonic velocity. Six failure types were identified during the uniaxial compressive strength tests. The strongest samples tended to fail through the matrix and the weakest rock samples tended to fail through haematized material or along haematized veins. Effective porosity and sonic velocity measurements could not distinguish between those samples that failed through the matrix and those that failed along discrete narrow veins. The presence of narrow haematized veins has a major effect on the intact rock strength

Engineering geology of British rocks and soils : Lias Group

The report begins with an introduction and a detailed modern assessment of the geology of the Lias Group in terms of both stratigraphy and lithology. The modern lithostratigraphy is placed in the context of the old, and sometimes more familiar, usage. The next two chapters deal with the mineralogy of a suite of samples collected for the project, and an assessment of the nature and influence of weathering based on a detailed analysis of the Lias dataset held in the BGS National Geotechnical Properties Database. The following chapters cover geohazards associated with the Lias Group, and a brief overview of the wide variety of industrial applications for which the Lias is well known. The geotechnical database forms the basis of the penultimate chapter, geotechnical properties. The contents of the database are analysed, interpreted, presented in graphical form, and discussed in terms of statistical variation and in the light of likely engineering behaviour. The engineering geology of the Lias Group is discussed in the final chapter, borrowing from the preceding chapters. A comprehensive cited reference list and a bibliography are provided. In addition to the large number of technical data provided to BGS, a small data set has been generated by BGS laboratories, particularly in areas where the main database was deficient, and also in connection with associated BGS studies of the swelling and shrinkage properties of the Lias Group. The individual items of data making up the database are not attributed. However, the contribution of a wide range of consultancies, contractors, authorities, and individuals is acknowledged. It is hoped that this report will provide a source of useful information to a wide range of engineers, planners, scientists, and other interested parties concerned with Lias Group materials. It should be noted that whilst quantitative technical data are included in this report, these should not be used as a substitute for proper site investigation

Increasing road network resilience to the impacts of ground movement due to climate change – a case study from Lincolnshire, United Kingdom

The UK road network is deteriorating due to ageing infrastructure, climate change and increasing traffic. Due to community and economic reliance on a functioning road system, there is an urgent requirement to build resilience. The roads of south Lincolnshire have high susceptibility to ground movement due to the underlying geology. Deposits such as peat, tidal flat deposits, and alluvium have a high susceptibility to compress, particularly when loaded, or through loss of water content driven by climate change or lowering of water in drainage channels. The shallow foundations of Lincolnshire's rural evolved roads, originating from old mud tracks, are poorly constructed, increasing their vulnerability to movement. Types of damage include longitudinal cracking, edge failure, and uneven long section profiles. Through knowledge exchange, data sharing and collaboration between the British Geological Survey and Lincolnshire County Council, a direct relationship between road condition and geohazard susceptibility has been demonstrated; showing compressible ground has a greater correlation with road damage than originally considered. This suggests improved understanding of the relationships between the geological, climatic, and anthropogenic driving forces on ground movement and road damage enables more informed repair prioritisation, decision support, and improved bespoke road repair practices, increasing future resilience of road networks

Shrinkage limit test results and interpretation for clay soils

The shrinkage limit is one of the Atterberg limits and is a fundamental geotechnical parameter used to assess the settlement of engineering soils containing clays, yet is rarely tested for as part of ground investigation. This paper describes shrinkage limit test results on a variety of soils from Britain and overseas obtained using an improved laboratory testing procedure developed at the British Geological Survey (BGS). The co-relationships with the other Atterberg limits and with density are explored. In particular, the coincidence of the shrinkage limit with the water content at the peak bulk density achieved in the test is examined. The shrinkage behaviour for undisturbed and remoulded states and a 3-way relationship between water content, density and suction are demonstrated. Some tropical residual and highly smectitic soils show a very wide range of shrinkage behaviour, albeit for a small dataset, when compared with the larger dataset of temperate soils tested. Consideration is given to limitations of the new and existing test methods

A 3D geological model for B90745 North Trans Pennine Electrification East between Leeds and York

This report and accompanying 3D geological model were produced for Tata Steel Projects. The report describes the bedrock and Quaternary geology of the study area, comprising 28 km (17.5 miles) of railway line between Leeds and York. The description and spatial distribution of each geological unit is based on the 3D geological model, which was constructed using 1:10,000 scale digital geological map data and 102 borehole logs from the British Geological Survey’s national archive. All boreholes located within the modelled area were considered in the construction of the geological model, together with key boreholes that fall outside the area of study. The top and base of weathered rock as defined is depicted as layers within the model

Material properties and geohazards

In engineering terms, all materials deposited as a result of glacial and periglacial processes are transported soils. Many of these deposits have engineering characteristics that differ from those of water-lain sediments. In the UK, the most extensive glacial and periglacial deposits are tills. Previously, engineering geologists have classified them geotechnically as lodgement, melt-out, flow and deformation tills, or as variants of these. However, in this book tills have been reclassified as: subglacial traction till, glaciotectonite and supraglacial mass-flow diamicton/glaciogenic debris-flow deposits (see Chapter 4, Sections 4.1–4.3). Because this classification is new, it is not possible to relate geotechnical properties and characteristics to the subdivisions of the new classification. Consequently, the domain/stratigraphic classification, recently developed by the British Geological Survey and others, has been used and their geotechnical properties and characteristics are discussed on this basis. The geotechnical properties and characteristics of the other main glacial and periglacial deposits are also discussed. For some of these (e.g. glaciolacustrine deposits, quick clays and loess), geohazards relating to the lithology and/or fabric of the deposit are discussed along with their properties. Other geohazards that do not relate to lithology and/or fabric are discussed separately as either local or regional geohazards. In some cases (e.g. glaciofluvial sands and gravels), the geotechnical properties and behaviour are similar to sediments deposited under different climatic conditions; these deposits are therefore not discussed at length. Similarly, some of the local geohazards that are found associated with glacial and periglacial deposits relate to current climatic conditions and are not discussed here. Examples include landsliding and highly compressible organic soils (peats)

Creation of the Till Thematic Layer

The national glacial tills dataset is one of a series of GIS thematic layers designed to help environmental scientists, planners, consultants and contractors assess the characteristics of the ‘near surface’. In particular, it focuses upon the material from which top soils and subsoils (A and B horizons) develop (i.e. from the base of the pedological soil down to approximately 3 m). According to DiGMapGB-50, Glacial Till covers approximately 30% of the land surface and makes up a majority of the Quaternary cover. It is known to be highly variable in its formation and in its particle size and lithological content