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Map summarising bedrock geology of the London Basin and the extent of 3D modelling; London LithoFrame (red) and Thames Gateway (blue). OS Topography ©Crown Copyright. All rights reserved 100017897/2008.
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As a provider of geological advice to industry, academia and the public, the British Geological Survey (BGS) has recognised the need to change the way it presents geoscientific information, resulting in the construction of attributed 3D geological models. The need to deliver D modelling solutions is of great importance in urban areas, where geologi...
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... in the London area has been completed for a variety of strategic scientific and commissioned projects, each fit for purpose at a range of scales. The Thames Gateway model (Figure 1) is built from over 4000 boreholes and over 2,300 line-kilometres of north-south and east-west trending cross-sections. The model includes a detailed subdivision of artificial ground, Holocene deposits and selected Bedrock units. The Thames Gateway model is commensurate with geological mapping at a scale of 1:10 000. A second modelling initiative, the London LithoFrame, extends model coverage of the London area to include Outer London, southwest Essex and northwest Kent (Figure 1). This strategic model is based on over 6,700 line-kilometres of correlated cross-sections. This model provides an equivalent level of detail to 1:50 000 scale mapping and represents the 3D equivalent of the geological map of London (Figure 3). The Thames Gateway and London LithoFrame 2 models occupy an area of approximately 3200 km . The combined model extends to a depth of 150 m, and represents a total of 38 units. In many parts of the model, borehole data is available in such large quantities that not all records can be used. A review and prioritisation of the available data ensures that the most reliable and representative records are incorporated in the model. Boreholes that are not considered initially can be introduced at a later stage to refine the interpretation. Further modelling at smaller and larger scale has been completed. These models provide additional information on the deeper structure of the London Basin, and very high levels of detail at specific sites (Royse et al., 2006a). All 3D models in the London area are constructed to integrate seamlessly across ...
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... in the London area has been completed for a variety of strategic scientific and commissioned projects, each fit for purpose at a range of scales. The Thames Gateway model (Figure 1) is built from over 4000 boreholes and over 2,300 line-kilometres of north-south and east-west trending cross-sections. The model includes a detailed subdivision of artificial ground, Holocene deposits and selected Bedrock units. The Thames Gateway model is commensurate with geological mapping at a scale of 1:10 000. A second modelling initiative, the London LithoFrame, extends model coverage of the London area to include Outer London, southwest Essex and northwest Kent (Figure 1). This strategic model is based on over 6,700 line-kilometres of correlated cross-sections. This model provides an equivalent level of detail to 1:50 000 scale mapping and represents the 3D equivalent of the geological map of London (Figure 3). The Thames Gateway and London LithoFrame 2 models occupy an area of approximately 3200 km . The combined model extends to a depth of 150 m, and represents a total of 38 units. In many parts of the model, borehole data is available in such large quantities that not all records can be used. A review and prioritisation of the available data ensures that the most reliable and representative records are incorporated in the model. Boreholes that are not considered initially can be introduced at a later stage to refine the interpretation. Further modelling at smaller and larger scale has been completed. These models provide additional information on the deeper structure of the London Basin, and very high levels of detail at specific sites (Royse et al., 2006a). All 3D models in the London area are constructed to integrate seamlessly across ...
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... bedrock geology of the London area covered by the 3D models is part of the London Basin, a NE- SW trending syncline ( Figure 1) (Ellison et al., 2004). The London Basin formed in Oligocene to mid-Miocene times, during the main Alpine compressional event that affected southeastern England. The oldest bedrock unit, the Cretaceous Chalk Group, crops out forming a rim around the Basin. The Chalk, which is over 200 m thick, is the region’s principal aquifer, famous historically for its artesian flow from wells sunk near the centre of the Basin and its susceptibilty to collapse due to dissolution. Overlying the Chalk, the oldest Paleocene deposit is the Thanet Sand Formation. This Formation consists of a sequence of fine- grained glauconitic sands with a basal bed of flint cobbles and boulders derived from the Chalk. The Thanet Sand reaches a maximum thickness of around 40 m in the east of the area but thins rapidly westwards to its limit beneath western London. Above the Thanet Sand lies the Lambeth Group. This lithologically variable group is up to 30 m thick in the area, consisting of variable proportions of sands, silts, clays and gravels. It is characterised by its spectacular colour-mottled clays which were prized for brickmaking. The overlying Eocene sediments form the Thames Group, which consist of the basal Harwich and an upper London Clay formations. The Harwich Formation consists predominantly of sand and pebble beds up to 10 m thick. The London Clay Formation comprises up to 150 m of grey to blue- grey, bioturbated, silty clay. Higher Eocene sediments of the sandy Bagshot Formation occur as isolated outliers on some of the highest hills in the area, reaching a thickness of around 30 m. Superficial Quaternary deposits are widely developed in the London area. These deposits include river and intertidal alluvium, peat, brickearth and river terrace deposits associated with the current and previous courses of the River Thames. Urban development and industrial mineral extraction in the region have resulted in a complex distribution of worked, made and infilled ground, collectively referred to as Artificial Deposits. The principal engineering geology and environmental factors associated with the geology of the London area are presented in Table 1 ...
Citations
... Additionally, a variety of 3D geological models has been constructed to aid resource evaluation [6,9], to explore geological conditions [30][31][32][33], and to study the geotechnical properties of the subsoils [7,10,34,35] to promote understanding of shallow subsurfaces. Researchers from the British Geological Survey [2,5,12,36,37] have constructed a variety of 3D geological models at all scales from sites to cities to the UK landmass and continental shelf using various software tools and modelling approaches [38]; Hou et al. [9] built a 3D geological model to establish the UUS quality level and distribution in Foshan city in Guangdong Province, China; Ye et al. [33] constructed a 3D model of land subsidence to simulate groundwater flow aquifer system displacements in downtown Shanghai (China); Høyer et al. [39] developed a high-resolution 3D geological model of Samsø (Denmark) to update the risk assessment of the Pillemark landfill; Anderson et al. [3] constructed an integrated 3D geological model of Vejle, Denmark, to support urban planning by providing planning maps; and Chen et al. [40] presented an integrated MPS-based 3D model framework in Minjiang Estuary area (China) to achieve more precise visualization for the subsurface structures. In general, 3D geological models have increasingly been used to improve understanding of geology at different scales. ...
Three-dimensional (3D) geological models are currently needed and used independently for urban development. The main difficulty in constructing a 3D geological model of a shallow subsurface is to determine the stratigraphic distribution. Highly variable properties and geometries of geological units beneath lead to difficulty. It is key to find a practicable and efficient way to construct a model in practical work. This study takes Tongzhou District (Beijing) as a case; 476 boreholes (40 newly drilled and 436 existing engineering boreholes) were utilized combined with the cross-section method to construct an integrated 3D geological model. The framework and analyses contributed to the following applications: (1) High-quality information from new boreholes and existing engineering boreholes were used to define stratigraphy and build cross-sections. (2) The resulting geological model (up to 50 m beneath Tongzhou area) shows many details of the shallow subsurface. This includes 10 major layers which were grouped into three cyclothems representing cyclic sequences of clay, interbedded silt, sand, and gravel with variable quantities of lenses. (3) The new model was used as a tool to visualize the depth and geometry variations below ground and to characterize a large variety of properties (for example, the compression modulus analyzed in this paper) that each unit contains, and then to evaluate the underground geological conditions. (4) An analysis of a dynamic monitoring model based on the resulting 3D model indicated that the geological units (sand and silty clay) at depths between 30 m and 40 m, with an average vertical deformation of 0.97 mm, from July 2019 to September 2020, are suitable for underground construction, from the perspective of vertical stability in the study area. Monitoring models that take time into consideration based on a 3D framework will be further explored.
... mapping of geotechnical properties and constructive conditions), and more recently the analysis of the effects of climate and future climate change. In Europe, there are among others, GIS-related research projects and databases at urban areas from countries such as Austria (Pfleiderer and Hofmann 2004), Belgium (Devleeschouwer and Pouriel 2009), UK (Ford et al. 2008;Royse et al. 2009), Finland (Vähäaho 1998), France (Marache et al. 2009;Thierry et al. 2009), Germany (Neber et al. 2004;Neumann et al. 2009), Greece (Koukis and Sabatakakis 2000), Italy (Rienzo et al. 2009;Ciotoli et al. 2015), Norway (De Beer et al. 2012), Portugal and Scotland (Campbell et al. 2010). The integration of subsurface urban environment in land-use planning and management was investigated and promoted by the COST Sub-Urban project, a European network involving geological surveys, local authorities and research partners (Campbell et al. 2014). ...
This paper describes the development of a GIS-based geotechnical system designed to face challenges on urban geology in a Spanish mid-sized city. Its multipurpose nature is based on a relational database that holds a wide variety of georeferenced ground data, mostly extracted from geotechnical reports or acquired during fieldwork. At present it includes, among other unpublished information, more than 2000 site investigations and the results from 5000 tests carried out on rock, soil and groundwater samples. This desk tool provides a better understanding of the bedrock and superficial geology through the spatial analysis of the collected subsurface data. The main achievements include the classification and mapping of man-made grounds, fluvial sediments and residual soils; the identification of unreported faults; the review and detailed study of geotechnical parameters and properties of the rocks and soils; and the hydrogeological characterization of the permeable units. It also provided the surface geological mapping of the urban area; the development of a geo-engineering map based on lithological, geotechnical and construction criteria; and the creation of a preliminary 3D layer-based ground model of the city centre, where the subsurface contains stone used for heritage buildings listed by UNESCO.
... Typically, planning maps, such as geotechnical soil properties, were presented as point information from boreholes or as two-dimensional (2D) maps, such as geological maps or overall contour maps showing the distribution and thickness of the individual units (see, Akpokodje, 1979;El May et al., 2010;Forster et al., 2004;Klein et al., 2013;Ozcep and Ozcep, 2011). During the last decades, three-dimensional (3D) geological models have been constructed for urban areas (see, Campbell et al., 2010;de Beer et al., 2012;de Rienzo et al., 2008;Ford et al., 2008;Marache et al., 2009b;Mielby and Sandersen, 2017;Terrington et al., 2019). The majority of these models portray the overall geological setting, and hence the geotechnical properties of layers, assuming the inherently limited variability of each unit; however, they typically do not have the discretisation (meters to decametres) to be used in sitespecific situations (Turner, 2006). ...
The increasing population density in existing urban areas often leads to the development of areas previously omitted due to construction risks. We suggest a comprehensive interpretation strategy exemplifying how planning maps should classify areas depending on risk and opportunities. The first steps of the interpretation strategy involve a review of the purpose of the project, followed by the acquisition of high-density geophysical data. In the subsequent steps, geophysical data in conjunction with GIS data are used for constructing a detailed high-resolution 3D geological voxel model. Specific geotechnical properties are assigned to the interpreted geological units based on in situ vane shear tests and the standard penetration test. In the final step of the interpretation strategy, two planning maps containing the three relevant themes are combined into one conclusive map demonstrating the recommended use of different parts of the area for future urbanisation. An isopach map showing the depth of the layers suitable for the foundation is combined with a map showing the areas flooded by the Vejle Stream during a 50- and 100-year event as well as habitat protected areas. Thus, the resulting planning maps show the most suitable locations of blue areas (lakes, wetlands), green areas (parks, etc.) and grey areas (buildings, roads) for future development.
The adopted interpretation strategy can be successfully applied in similar situations to reduce the risks associated with urban development.
... Hutchinson (1980) suggested that where it is reduced to less than 35 m in thickness pore pressures were sufficient to breach the confining effect of the London Clay Formation and allow a restricted supply of water to surface. A 3D bedrock geology model for areas of central London has been developed by the BGS using borehole lithological records, geological surface line work and a digital terrain model (Ford et al. 2008). The model is based on over 6700 line-km of correlated cross-sections providing a level of detail equivalent to 1:50000 scale mapping (Ford et al. 2010). ...
Engineering works carried out in central London over many decades have revealed a number of buried hollows that exhibit curious characteristics. Some extend deep into the bedrock geology and are in-filled with disturbed superficial deposits and reworked bedrock. Others are contained within the superficial deposits. They can be up to 500m wide and more than 60m in depth. As the infill material often has different behavioural characteristics from the surrounding deposits failure to identify them during an initial site investigation can prove costly. This paper considers their common characteristics and describes the method used to develop a buried hollow hazard susceptibility map. This map provides planners with a broader awareness of the potential location of difficult ground conditions associated with them, thereby reducing the potential for unforeseen ground conditions through effective site investigation design. The paper continues with a discussion of some of the likely processes associated with their formation, which are attributed to cryogenic processes, and concludes with potential future research directions.
... The fault network resolved at the intended model resolution was initially established in GSI3D by 3D visualisation of the data to detect significant offsets of the strata (Ford et al., 2008(Ford et al., , 2010. In order to create the faulted surfaces of the bedrock geological units, the interpreted sections, the unit extents and the faults were then exported to GOCAD 1 , where a standard workflow for model construction was used to generate the faulted surfaces. ...
... Use as a framework for the construction of higher resolution, more detailed geological models for site-specific and local studies. Ford et al. (2008Ford et al. ( , 2010 and further changes to the bedrock unit croplines. Catchment and regional scale assessments for hydrogeology, planning and mineral resource estimation. ...
Many geological survey organisations have started delivering digital geological models as part of their role. This article describes the British Geological Survey (BGS) model for London and the Thames Valley in southeast England. The model covers 4800 km2 and extends to several hundred metres depth. It includes extensive spreads of Quaternary river terraces and alluvium of the Thames drainage system resting on faulted and folded Palaeogene and Cretaceous bedrock strata. The model extends to the base of the Jurassic sedimentary rocks.
The baseline datasets used and the uses and limitations of the model are given. The model has been used to generate grids for the elevation of the base of the Quaternary, the thickness of Quaternary deposits, and enabled a reassessment of the subcrop distribution and faulting of the Palaeogene and Cretaceous bedrock units especially beneath the Quaternary deposits.
Digital outputs from the model include representations of geological surfaces, which can be used in GIS, CAD and geological modelling software, and also graphic depictions such as a fence diagram of cross-sections through the model. The model can be viewed as a whole, and be dissected, in the BGS Lithoframe Viewer. Spatial queries of this and other BGS models, at specific points, along defined lines or at a specified depth, can be performed with the new BGS Groundhog application, which delivers template-based reports.
The model should be viewed as a first version that should be improved further, and kept up to date, as new data and understanding emerges.
... None of the faults is shown on current geological survey maps although the existence of the Barbican Fault had been shown by regional 3D geological models of the London area (Ellison et al. 2004, fig. 45;Ford et al. 2008). One, the Smithfield Fault, was known from previous desk studies for Crossrail and the existence of two others had been suspected, although their position and orientation were poorly constrained. ...
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 risk.
... CULSHAW et al. (2006) explained a needs for provisioning of digital spatial data for engineering geologist with examples of using those data for 3D modeling and creating fence diagram of Swansea/Port Talbot area. A modern approach to geological survey- ing and its relevance in the urban environment with examples of the 3D geology of London and the Thames Gateway was presented by FORD et al. (2008). ...
The recent developments in earth sciences software are mostly related to the extension allowing
graphical representations of volumes and geological bodies. In this paper, we present a tool for 3D visualizationof landslide body using only ArcGIS© software and its 3rd party extensions. The model was built using existing geological surveys, DEMs, borehole logs and site investigation data. The case study chosen to illustratethe method is the Umka landslide (Belgrade, Serbia), an area with relatively simple geology, but withdeep seated landslide and with block-translational sliding mechanism.
The near-surface of London is faulted; however, their locations, architecture and tectonic origins are broadly unknown. This presents serious issues for geotechnical engineering in London and has implications for our structural understanding of the London Basin.
The region is a product of Alpine compression, yet it is unclear if these major faults were new Alpine shears or reactivated basement faults. Here the plausibility of Alpine reactivation and inheritance of basement faults in London is assessed through three investigations: analysing structures in the near-surface; mechanically assessing the feasibility of basement fault reactivation under Alpine stress conditions; and comparing inheritance mechanisms with observations in London and the Thames Estuary.
Three major en échelon fault sets have been identified. These appear to have compartmentalised London's near-surface geology and are interpreted to all be products of Alpine reactivation of underlying basement faults. Fault interaction and linkage is evidenced by complex zones of intense faulting identified by tunnelling projects. The role of new structure development in accommodating Alpine compression is considered to have been comparatively minor.
The lack of major faulting in the Basin's interior may reflect the competence of the underlying Anglo-Brabant Massif in restricting Alpine strains to its margins.
Three-dimensional (3D) geological modeling has been developed in recent decades to overcome the complex nature of shallow superficial deposits in urban areas as a result of urbanized advancement. To meet the requirements of 3D geological models in the urban underground space construction in Beijing City, we constructed a coupled 3D model of geological sequences setting up to 50 m from the surface, and geotechnical properties of subsoils in Beijing for the first time via Creatar Xmodeling software. The modeling relies on 107 intersecting cross-sections and the horizons-to-solids approach aims to provide an insight into related modeling projects, especially in a complicated alluvial environment. In this paper, we described detailed modeling procedures, exhibited the outputs from the 3D model (combined geological units, cross-sections or fence diagrams, and properties presented in the form of horizontal distribution maps), and analyzed typical engineering properties of silty clay and clay units. The achieved 3D attributed model provides geologists an effective method to visualize the property characteristics of each layer and the potential connections between them, thereby to predict underground conditions and to reduce risks in geotechnical engineering processes such as urban underground constructions.
There is an underuse of geological knowledge in society. Therefore, an unused potential of more informed decision-making and planning as well as improved solutions on societal challenges exist. The aim of this study was to better understand the geological map user and to improve the usability of geological map products. With the aim of improving graphical communication through maps and images, visual research methods are used. The sketch map method, which has been used since the 1960s, is used here to elicit information about people and their image subsurface geology of a city. The participants include students in area planning and experts within geology. Content, semiotic and visual analyses were performed on the sketches produced by the participants. The results show limited knowledge of geology and a lack of common geological language, both graphical and linguistic. Improved ways of representing the subsurface are identified, which can be used as input to more intuitive future designs. Adapting to the user’s image of subsurface geology, usability could be increased by using plain language, adding landmarks, pictographic symbols and patterns to geological visualizations. This could potentially lower the user threshold, trigger interest and raise the awareness of local urban geology.
