Relating in situ hydraulic conductivity, particle size and relative density of superficial deposits in a heterogeneous catchment

Estimating the permeability of superficial deposits is fundamental to many aspects of catchment science, but can be problematic where insufficient in situ measurements are available from pumping tests in piezometers. Consequently, common practice is to estimate permeability from the material description or, where available, particlesize distribution using a formula such as Hazen. In this study, we examine the relationships between particlesize, relativedensity and hydraulicconductivity in superficial deposits in Morayshire, Northern Scotland: a heterogeneous environment typical of many catchments subject to previous glaciations. The superficial deposits comprise glaciofluvial sands and gravels, glacial tills and moraines, raised marine sediments, and blown sands. Thirty-eight sites were investigated: hydraulicconductivity measurements were made using repeated Guelph permeameter measurements, cone resistance was measured in situ with a Panda dynamic cone penetrometer; material descriptions were made in accordance with BS5930:1999; and disturbed samples were taken for particlesize analysis. Overall hydraulicconductivity (K) varied from 0.001 m/d to >40 m/d; glacial till had the lowest K (median 0.027 m/d) and glacial moraine the highest K (median 30 m/d). However, within each geological unit there was great variability in measured hydraulicconductivity values. Multiple linear regression of the data indicated that log d10 and relativedensity (indicated by cone resistance or BS5930:1999 soil state description) were independent predictors of log K and together gave a relationship with an R2 of 0.80. Material description using the largest fraction (e.g. sand or gravel) had little predictive power. Therefore, in heterogeneous catchments, the permeability of superficial deposits is most strongly related to the finest fraction (d10) and relativedensity of the material. In situ Guelph permeameter measurements at outcrops with good geological characterisation provide an easy and reliable method of determining the permeability of particular units of superficial deposits

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

Subgrade geology beneath railways in Manchester

It is not sufficient to identify fine-grained soils, only, as locations for potential subgrade problems as could be done using a traditional 2D geological map. More information is required about the geological structure, lithological variability, mineralogy, moisture content and geotechnical properties of the soil, much of which can be supplied by modern 3D geospatial databases. These databases can be interrogated at key depths to show the wide variability of geological materials and conditions beneath the ground surface. Geological outcrop and thickness of bedrock an superficial deposits (soils), plus the permeability and water table level are predicted from the Manchester geospatial model that is based on 6500 borehole records. Geological sections along railway routes are modelled and the locations of problem soils such as alluvium, till and glaciolacustrine deposits at outcrop and shallow subcrop are identified. Spatial attribution of geotechnical data and simple methods to recast sections in engineering geological terms are demonstrated

Summary Report of FORGE WP4.1.2: verification of critical stress theory applied to repository concepts

This report outlines the major conclusions from an experimental study of 48 separate experiments with the primary aim to verify critical stress theory. Two main types of experiment were conducted: 1). Loading-unloading tests, where fracture flow was monitored at constant injection pressure as normal load was increased in steps to a given level and then reduced back to the starting stress state; 2). Gas breakthrough experiments, where gas injection pressure was increased in a pressure ramp at constant vertical load. These were conducted with and without active shear. It was found that critical stress theory is valid in predicting the preferential flow of gas in relation to the orientation of the fracture plane with respect to the maximum horizontal stress direction. However, loading unloading experiments showed that understanding the stress history of the rocks is of paramount importance and a mere knowledge of the current stress state is insufficient in accurately predicting the nature of fluid flow

Landslide and mass movement processes and their distribution in Longdendale Valley and Glossop District (sheet 86)

This report describes the geographical extent of the landslides and the mass movement mechanisms responsible for landslide deposits in the Longdendale valley. In addition an overview of the slope processes in the Glossop district is also presented

Measurement and correlation of acoustic emissions and pressure stimulated voltages in rock using an electric potential sensor

Previous laboratory-based studies have demonstrated pressure stimulated currents and electromagnetic emissions in rock and cement mortar can be used to assess damage. There is some debate whether the current and electromagnetic emission measurement technologies used thus far are viable for field application. The results presented here provide evidence that electric potential sensors are a viable new technology for field monitoring of electrical emissions. Cylindrical specimens of rock were loaded at constant stress or strain rates until failure occurred; strain gauges, piezoelectric transducers and electric potential sensors were used to monitor the strain, acoustic emissions and pressure stimulated voltages. Pressure stimulated voltages were observed in the linear elastic and inelastic deformation regions of loading, suggesting that pressure stimulated voltages are associated with microcracking and macrocracking events. Electric potential sensors are potentially a cost effective and more advanced alternative to piezo transducers and geophones for structural health monitoring of rocks

Model metadata report for Manchester and Salford, NW England

This report describes the creation of a 3D geological model of natural and artificial superficial deposits in Manchester and Salford, NW England. The Manchester and Salford model forms part of the Lower Mersey Corridor, NW England. The Lower Mersey Corridor includes models within the region comprising: Manchester-Salford Warrington Liverpool Irlam The location of the geological models is shown in Figure 1 and the spacing of cross-sections is shown in Figure 2. Figure 1 Location of Manchester and Salford 3D geological model and its relationship to others in the Lower Mersey Corridor area of NW England. The 3D models include natural and artificial superficial deposits. Cross-sections for Manchester and Salford include schematic bedrock correlations for illustration only. Bedrock is not included in the calculated mode

Integrated modelling of geoscience information to support sustainable urban planning

The provision of reliable and up-to-date geoscientific information for the urban environment has assumed increasing importance in recent years as legislative changes have forced developers, planning authorities and regulators to consider more fully the implications and impact on the environment of large-scale development initiatives. To comply with the principles of sustainable development, developers are increasingly required to demonstrate that proposals are based on the best possible scientific information and analysis of risk. Nowhere is this more relevant than in the context of urban regeneration, where planning policy guidance gives priority to re-use of previously developed (brownfield) land. In England, brownfield sites suitable for re-development cover an area equivalent to half the size of London

The ASK Network: developing a virtuous cycle of subsurface data and knowledge exchange

Knowledge of the subsurface is essential in delivering successful construction and regeneration projects. Inadequate understanding of subsurface ground conditions can constrain effective development of urban areas and is a key factor in project delay and overspending. Improving this situation demands much better use, and re-use, of subsurface data and knowledge. The establishment of ASK subsurface data and knowledge exchange network has led to substantial improvements in how urban subsurface data is reported and exchanged between the public and private sectors. Implementation of the GSPEC standardised digital data reporting format has improved the integrity and accessibility of data. ASK and GSPEC are enabling the expansion and exchange of high quality systematic subsurface datasets, improving development of robust 3D ground models which can be used to promote more cost effective and better informed ground engineering investigations, and monitoring and regulation of resources in the urban environment. The work underway in Glasgow is acting as a standard for change, both within the UK and Europe

Landslide hazard assessment for National Rail Network

There have been a number of high profile reports of landslides on the national rail network of Great Britain (comprising England, Scotland and Wales) over recent years. Events range in size from small wash out failures (St. Bees, Cumbria) to well publicised large failures causing major longer term disruption (Hatfield Colliery, South Yorkshire). In conjunction with negative media attention, derailment and damage to railway infrastructure, failures along the rail network have the potential to cause injury and loss of life. The national rail network comprises ten strategic routes that cover a variety of terrains and geologies. The British Geological Survey (BGS) have produced, for Network Rail, a high level susceptibility model of landslide hazard from Outside Party Slopes adjacent to the strategic rail network. This assessment was compiled based on Geographic Information System (GIS) techniques and historical landslide records (landslide inventory). The model was designed to give a high level overview of potential landslide hazard to Network Rail senior management and individual Route Asset Managers. The national study adopted a fixed buffer style analysis of each 5 chain section (∼100 m length) of the entire railway network. It included event data from the BGS National Landslide Database superimposed on mapped data from the BGS GeoSure land instability susceptibility model and geologically mapped landslide polygons. The National Landslide Database is the most comprehensive inventory of landslide events in Great Britain. The BGS GeoSure slope instability layer provides a scientifically based 1:50 000 scale assessment of national susceptibility to natural slope failure. The results of this study have been provided as a spatially attributed dataset with total hazard susceptibility scores A (low)–E (high). Maximum hazard scores are attributed for both up and down- track and 5 chain length for the full network. A high score indicates where conditions imply a significant potential for future landslide hazard. Further refinement of the hazard layers are being developed by BGS to include specific landslide processes such as Rockfall, Earthflow and Debris Flow hazards