Boulder Clay Research Articles

Alleviation of Both Water and Nutrient Limitations is Necessary to Accelerate Ecological Restoration of Waste Rock Tips

Hard rock quarries are commonly located close to national parks and special areas of conservation and are generally regarded as visually intrusive. Consequently, restoration strategies that effectively accelerate natural plant regeneration processes are required. Slate waste tips present extreme conditions for plant establishment with multiple potential limiting factors (e.g., lack of organic matter, nutrients, and poor water retention). In this study, we investigated ecological strategies to accelerate natural regeneration at the largest slate quarry in Europe. A field experiment was conducted to assess ecosystem restoration using a contrasting set of native woody species. Treatments included amendments of waste tips with: polyacrylamide gel to increase water-holding capacity; mineral fertilizer to increase nutrient supply; and two treatments that increased both (organic waste or boulder clay addition). Ecosystem recovery was evaluated through above- and below-ground productivity (plant and microbial, respectively) and soil analyses. Neither increasing nutrient supply (with mineral fertilizer) nor water-holding capacity (with polyacrylamide gel) was sufficient, alone, to improve plant establishment. However, both boulder clay and organic waste amendment significantly enhanced plant growth. There was a marked positive interaction in the effects on tree growth of the amendment with organic waste and boulder clay. Large interactions occurred between tree species and substrate amendments. The growth of N(2)-fixing species was strongly favored over non-fixers where there was no addition of material increasing soil nitrogen supply, whereas the growth advantage of pioneer species over non-pioneers was greatest with fertilizer, organic waste, or clay additions. Organic waste addition had the greatest positive impact on soil processes.

DESTRUCTIVE WAVE OVERTOPPING TESTS ON GRASS COVERED LANDWARD SLOPES OF DIKES AND TRANSITIONS TO BERMS

In 2009 tests have been performed at the Afsluitdijk, the closure dike of Lake IJssel in the Netherlands. This dike has a sand core covered by layers of clay and boulder clay, and a grass cover. In 2010 succeeding tests were performed at a river dike near Zwolle. This dike was a sand dike with a grass cover. In all of these tests research was performed on the behaviour of the grass cover on the landward slope of the dikes. Furthermore, the influence on erodibility of the grass cover caused by damage of the grass cover by mice, moles or other influences like tractor tracks were investigated. Also the influence of obstacles or other elements, which may be present at dikes, was part of the investigations (tree, stairs, fence, maintenance road). It was observed that all of these influences are to some extent contributing to a decrease of the resistance against failure.

Comparison of the measured and finite element–predicted ground deformations of a stiff lodgement till

The use of the finite element method to model excavations and tunnels in Dublin black boulder clay has, in the past, had limited success owing to the failure of the available constitutive models in commercially available software programs to adequately represent the essential features of a stiff soil. A stiff soil — lodgement till — underlies much of the city of Dublin, Ireland; consequently, the successful prediction of deformations in this soil arising from structural and infrastructural projects is of considerable importance. Research has shown that the stress–strain response of a stiff soil is complex and depends on many factors including stress history, stress level, and strain direction. These important features are included in the hardening plasticity small strain stiffness (HSS) soil model that is incorporated in the Plaxis V8.4 finite element code. This paper describes the field and laboratory methods that were used to determine the parameters for incorporation in this soil model and the validation of these parameters. These parameters are used to model the deformations around two excavations: a 4.5 m deep excavation with a vertical face, and a 10.7 m deep excavation with a face slope of 70°–75°. Good agreement was found between the predicted and observed deformations.

Settlement evaluation of spread foundations on heavily preconsolidated cohesive soils

Settlement evaluation of spread foundations on heavily preconsolidated cohesive soils. The paper presents the results of fi eld and laboratory tests performed on the heavily preconsolidated boulder clays which prevail on the campus of the Warsaw University of Life Sciences – SGGW as foundation layers. Based on the results of fi eld and laboratory tests a problem of spatial variability assessment of the thickness of foundation layers and the soil parameters is discussed. Special attention is drawn to the selection of the design values of oedometer moduli and the suitability of calculation methods for settlement evaluation. Calculated settlements were approved by the fi eld measurements performed during building construction.

Mineralogy of selected geological deposits from the United Kingdom and the Republic of Ireland as possible capping material for low-level radioactive waste disposal facilities

Solid low-level radioactive waste (LLW) is currently being disposed at a number of facilities in the United Kingdom (UK). The safety of these facilities relies to some extent on the use of engineered barriers, such as a cap and a liner, to isolate the waste and protect the environment. Generally, the material used as the barrier layer within such a cap should be of low permeability and it should retain this property over long timescales (beyond a few decades normally required for facilities containing non-radioactive wastes). The objective of this research is to determine the mineralogy of selected geological deposits from the UK and Republic of Ireland as part of a larger project to examine their suitability as a capping material, particularly on LLW sites. Mineral transformations, from weathering, may impact on the long-term performance of the cap and even the disposal facility. These transformations could be brought on or enhanced by climate change. X-ray diffraction (XRD) was carried-out on the sand, silt and clay fractions of the London Clay, Belfast Upper Boulder Clay, Irish Glacial Till, Belfast Sleech, and Ampthill Clay geological deposits. Minerals were present that could pose both positive and negative effects on the long-term performance of the cap. Smectite, which has a high shrink swell potential, may produce cracks in London Clay, Belfast Upper Boulder Clay and Ampthill Clay capping material during dry, hotter periods as a possible consequence of future climate change; thus, resulting in higher permeability. Ampthill Clay and Belfast Sleech had elevated amounts of organic matter (OM) at 5.93% and 5.88%, respectively, which may also contribute to cracking. Over time, this OM may decompose and result in increased permeability. Gypsum [CaSO 4] in the silt and sand fractions of Ampthill Clay may reduce the impact of erosion during wetter periods if it is incorporated into the upper portion of the cap. There are potential negative effects from the acidity created by the weathering of pyrite [FeS 2] present in the silt and sand fractions of Belfast Sleech and Ampthill Clay that could impede the growth of grasses used to stabilize the surface of the capping material if this material is used as part of the vegetative soil layer. Additionally, acidic waters generated from pyrite weathering could negatively impact the lower lying capping material and the disposal facility in general, because they could react with contaminants and weaken vessels storing contaminants. However, calcium carbonate [CaCO 3] present in the silt and sand fractions of these deposits, and dolomite [CaMg(CO 3) 2] in Belfast Sleech, may counter act the acidity.

Simulation of Vegetative Induced Deformation in an Unsaturated Soil

Problem statement: Tree root water-uptake increases soil strength by increasing the soil matric suction due to pore pressure dissipation in a soil mass, inducing increases in vertical total s tress or water extraction, the effective stress to which the soil strata is subjected to may also increase. This causes volume change which might be detrimental to geotechnical structures and shallow foundation. Approach: This study proposed a methodology that can be used for the prediction of the root water- uptake and deformation. It was suggested that negat ive pore-water pressures can be estimated through two-dimensional governing equation for unsaturated soil and was converted to axi-symmetrical form due radially nature of tree roots. Results: The results of the root water-uptake analysis were then used as input for the prediction of ground displacements in a stress-deformation analysis. A volume change was modeled as a result of matric suction change ca used by vegetative induced moisture migration. The proposed method was studied and tested against data collected on a case history involving a mature Lime tree on Boulder clay at Stacey Hall, Wolverton, England and mechanical properties of Boulder Clay. The recommended safe planting distance of trees of height, H, from buildings a distance, L, away is in form of L: H≥0.5 m ratio. Conclusion: The predicted results from the two dimensional axi-symmetrical analyses agree well wit h the measured data in terms of both total vertical displacements and final water contents in the soil. Based on hypothesis, the numerical model developed provides practicing geotechnical engineer s an effective tool for designing structures on vadose zones containing vegetation.

An assessment of the earth pressure coefficient in overconsolidated clays

The determination of the earth pressure coefficient K0 in a natural clay deposit is a problem of considerable significance in geotechnical engineering. While the methods for evaluation of K0 are reliable for normally consolidated soils, significant difficulties still exist in evaluating K0 in overconsolidated clays, given that it is influenced by the stress history of the material, together with the age, structure, mineralogical composition and depositional environment. Indeed, some of these factors are responsible for the soil becoming anisotropic. The existing framework for prediction of K0 in overconsolidated soils does not account for any influences caused by anisotropy. The work reported in this paper evaluates the validity of a revised relationship between K0oc and OCR (overconsolidation ratio) using data obtained from laboratory investigations. The tests were performed on reconstituted and undisturbed samples of Belfast Upper Boulder Clay, London Clay and Gault Clay. Tests were also performed on reconstituted samples of kaolin. The values of K0oc were determined using various approaches, including on-sample measurements. The results have confirmed that reliable predictions of K0oc can be made using the proposed relationship.

The ice age paleo-channel Ellerbeker Rinne an integrated 3D gravity study

In the framework of a joint field work with partners of the Landesamt fur Landwirtschaft, Umwelt und landliche Raume (LLUR, the former LANU; Flintbek, Germany) and the Leibniz-Institut fur Angewandte Geophysik (LIAG; Hannover, Germany) gravity measurements have been conducted in July 2005 by members of a student course Geophysical field exercise in the area of the Ellerbek paleo-channel near Tangstedt. At approximately 450 stations complete Bouguer anomalies have been calculated. The error of gravity anomaly accounts for 2 x 10(-7) m/s(2) (max.) to -8 x 10(-7) m/s(2) (min.). The gravity field of the region is affected by a strong regional gravity field, which is caused by salt structures. Therefore, a regional field was calculated which based on a regional survey of the State Geodetic Survey. It was subtracted from the Bouguer field and a slightly negative residual field (-1.0 to -1.5 x 10(-5) m/s(2)) resulted in the area of the Ellerbek paleo-channel. It was analysed and interpreted by curvature algorithms, Euler deconvolution and 3D modelling. Euler deconvolution and curvature result in a depth of max. 400 m for this part of the Ellerbek paleo-channel; clusters of Euler source points were also calculated for depths of 130 m and 220 m which points to rather inhomogeneous infill of the channel. The compiled 3D density model was constrained by the seismic profile P3 of LIAG and borehole information. The model explains the positive anomaly north of Tangstedt (> 1.5 x 10(-5) m/s(2)) With a high density body (Geschiebemergel; boulder clay) of 300 kg/m(3) density contrast to the sedimentary infill of the paleo-channel which has its bottom at 200 m depth.

Substrate dependency of Lateglacial forests in north‐east Germany: untangling vegetation patterns, ecological amplitudes and pollen dispersal in the past by downscaling regional pollen

AbstractAim Palynology has revealed that during the Lateglacial Allerød period, Pinus and Betula dominated the forests of north‐east Germany. Because of implicit restrictions, however, palynology fails to reconstruct in detail the distributional patterns and whether monospecific or mixed forests prevailed. Here we test the hypothesis that the distributional patterns of Pinus and Betula were largely determined by substrate.Location Fifteen sites in north‐east Germany.Methods As pollen data reflect the abundance of taxa around a sample site, our hypothesis implies that the abundance of e.g. Pinus pollen should reflect the abundance of substrate types that are favoured by Pinus. (In order to differentiate clearly between taxa and pollen types, the latter are displayed in small capitals.) We analysed the percentage of Pinus and Betula pollen from an interval in the Allerød, and their relationship to the present‐day proportion of the two dominant substrate types (sand and boulder clay). The substrate proportion was determined in rings from 1 to 50 km around all sites, using four distance‐weighting functions.Results Pollen percentages of Pinus are linearly related to the proportion of sand, and Betula percentages to the proportion of boulder clay. The highest coefficients of determination (r2 = 0.89 and 0.91, respectively) were observed for radii of c. 30 km, with distance weighting by 1 and 1/d.Main conclusions The present‐day distributional pattern of substrate types strongly indicates the distributional pattern of Pinus and Betula in north‐east Germany in the Allerød. Assuming that the pattern of substrates remained broadly constant, Pinus dominated on sand and Betula on boulder clay. Our new method thus enables us to refine significantly the reconstruction of habitat characteristics and distributional patterns of taxa in the Lateglacial and Holocene, independent of their present‐day ecological amplitudes. The good performance of the distance‐weighting functions 1 and 1/d indicates that the pollen source area of a site has rather discrete boundaries determined by convective air movements during daytime. Within these boundaries, pollen is evenly distributed over various distances. This implies that light pollen types are transported further than predicted by Sutton’s equation on particle dispersal.

Advantage of Bayesian approach to geotechnical designing

Advantage of Bayesian approach to geotechnical designing The paper addresses the possibility of the Bayesian approach's application to geotechnical engineering. First the principal information on the Bayesian analysis has been presented and its applications to estimate the soil parameters based on the CPT/DMT tests at SGGW Campus in Warsaw afterwards. The CPT/DMT tests had been carried out in order to recognize the geotechnical conditions in the foundations of design campus buildings. The data from two layers of glacial boulder clays have been analysed. The results demonstrate that the Bayesian approach is a useful tool in evaluation of ground properties and estimation of the geotechnical parameters in specified circumstances.

Biological Flora of the British Isles: Primula elatior (L.) Hill

Summary This account presents information on all aspects of the biology of Primula elatior that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation. Primula elatior is a native perennial herb, within a compact area in the British Isles, in ancient woods and copses on the chalky boulder clay in East Anglia, where it is abundant locally although scarce nationally. British material is ssp. elatior, which extends across much of Europe, becoming rarer towards the south. Primula elatior is a shade tolerant species, but only flowers in profusion in the increased light levels following tree felling in traditionally coppiced woods. It is confined to an area of the British Isles where the soils are seasonally waterlogged and ill‐aerated, and is very tolerant of the toxic levels of ferrous iron which accumulate in the surface horizons in the spring months. It has a poorly developed drought tolerance. An early flowering plant, P. elatior is an insect‐pollinated obligate outbreeder, with two self‐incompatible morphs (pin and thrum). The low colonizing ability of this ancient woodland species can be attributed to both seed dispersal and seedling recruitment limitation. There has been a steady reduction in the density of P. elatior in woodland sites during the past centuries. However, there has been little change in the 10‐km distribution in the British Isles. Studies of populations involve three groups of factors: genetic variation, environmental changes and population structure. Potentially these factors have a greater effect on small and isolated populations than on large and integrated ones. There is no evidence that the species suffers from a loss of genetic diversity in the smaller populations. Primula elatior seems to have a relatively high level of genetic diversity that is maintained despite a fragmented distribution. Within its restricted distribution area P. elatior replaces P. vulgaris completely. At the margins of their distributions the two species occur together in a number of woodland sites, providing the opportunity for hybridization. As they are highly interfertile, hybridization is restricted mainly by differences in their habitat preferences. The hybrid P. vulgaris × P. elatior = P. × digenea is fertile and gives rise to hybrid swarms which are found in all British sites where both parents occur together. Changes in climate, woodland management practices and intensities of deer grazing, especially by Fallow deer (Dama dama), are likely to have a major effect on populations of P. elatior. Since the species colonizes new or secondary woodlands very slowly, management should focus on the conservation of ancient semi‐natural woodlands.

Axial resistance of CFA piles in Dublin Boulder Clay

This paper describes the results of static compression and tension load tests performed on three-instrumented large-diameter continuous flight auger piles installed in Dublin Boulder Clay. The piles developed very high shaft resistance and, in contrast to piles driven into Boulder Clay that exhibit friction fatigue, the shaft distribution was uniform along the pile shaft. This resulted in the normalised average shear resistance being mobilised by a bored pile exceeding that of a pile driven in similar ground conditions. In contrast, the base resistance of the test piles was significantly lower than that of a pile driven in similar ground conditions.

Finite element analyses of steep man-made cuts in Dublin boulder clay

This paper describes finite element analyses undertaken to gain an insight into the short-term behaviour of temporary steep slopes in Dublin boulder clay for cut and cover sections of the recently completed Dublin Port Tunnel. The analyses of two steep slopes are reported: (i) an unsupported slope for a full-scale trial excavation and (ii) a partly nailed slope for a prototype cut and cover structure. It has been found that a major contribution to the stability of these cuts is an increase in the effective stress (and thus strength) due to both (i) depressed pore-water pressures (suctions) and (ii) a tendency of the Dublin boulder clay to dilate during undrained excavation in this low permeability and very dense material. However, the presence of even thin, discontinuous but recharged granular lenses of a higher permeability significantly reduces the time to failure.

Geotechnical properties of Dublin Boulder Clay

Geotechnical characteristics of Dublin Boulder Clay (DBC), based on detailed site investigation and site experience from some recent large projects in Dublin, are presented. This paper attempts to synthesise available information in parallel with recent work by Skipper et al., who provide an updated understanding of the geology of the DBC. Having assessed the effects of sampling disturbance, the paper characterises the various formations and sub-units of the DBC. The interpreted material behaviour is related to observed engineering performance. It was found from the behaviour of earth retained structures that intact, clayey, DBC formations are two to three times stiffer than assessed from high-quality laboratory tests on block samples. DBC is shown to be significantly stiffer than other well-characterised tills. Relatively inexpensive multichannel surface wave techniques can give very reliable estimates of in situ small-strain stiffness. High undrained triaxial compression strengths were measured, and it appears that simple UU tests on high-quality specimens give good results. Significant strength anisotropy was suggested by undrained triaxial extension strengths that were only 30–50% of the triaxial compression strengths. Field horizontal permeability values of the intact clayey till units have a representative mean of about 10−9 m/s, and when compared with laboratory values suggest that the material may exhibit some degree of anisotropy of permeability. Overall, the measured engineering parameters for the DBC are favourable for many construction projects. Further work is required in order to understand the in situ horizontal stress profile and the stiffness anisotropy of the till.

An investigation into the genesis of an erratic (retro) eclogite block from Haren, Groningen, the Netherlands

AbstractIn boulder clays and glacial deposit sands, exposed in the northern part of the Netherlands, erratic blocks of (ultra)high pressure (UHP) metamorphic rocks may be found that originate from the Baltic Shield (Scandinavia). The occurrence of (U)HP metamorphic rocks in Scandinavia is limited to: (1) isolated occurrences within the Scandinavian Caledonides (Western part of Scandinavia); (2) Sveconorvegian rocks from the Halland area, Southwest Sweden; and (3) Kola Peninsula (Northern Scandinavia). For this reason (U)HP rocks form excellent indicator pebbles/rocks that may be used to trace back the source area from where the erratic blocks, found in the Netherlands, were derived. An example of this, an erratic (retro) eclogite block found in Haren, is investigated in the present study using naked eye, light-optical and electron microprobe (EMP) techniques. EMP mineral analyses were used to reconstruct the PT conditions under which the (retro) eclogite was formed (T = 756 °C/min. P = 16,2 kb). This result, in combination with the mineral chemistry of the major rock forming minerals, provides evidence that this erratic block originates from the upper HP tectonic lens exposed in the Caledonian Seve Nappe Complex of Northern Jämtland, Sweden.

Evaluation of the soil penetration resistance along a transect to determine the loosening depth

The objective of this study was to evaluate the distribution of soil strength (measured as cone index, CI) along a 600 m transect and to determine the soil loosening depth necessary to eliminate zones with soil strengths exceeding a threshold value down to a depth of 0.6 m. The transect was located at a site in a glacial drift area which was characterised by sandy deposits overlying boulder clay. A tractor-mounted multi-penetrometer array consisting of four hydraulically driven single vertical penetrometers was used to determine CI at 1-m sampling intervals as a measure of penetration resistance. The spatial fluctuation of the CI readings in general and that of repeatedly averaged readings along the transect was examined. Furthermore, the relationships between the penetration resistance of several soil layers and the relationships between the CI of single penetrometers were identified. Averaged CI values over 5-m intervals were used to determine the depth of soil loosening required. By using various data sub-sets based on the averaged data of the four array mounted penetrometers and simulating several different sampling intervals, treatment intervals and threshold values of soil strength, a sampling interval of about 10 m proved to be sufficiently accurate to determine the loosening depth required.

Gravity investigation of buried Pleistocene subglacial valleys

Buried Pleistocene subglacial valleys are important geological structures in northern Germany and are used extensively for groundwater production. Details of their occurrence, their structure, and the hydraulic properties of their sediments are not well known. In recent years, seismic and geoelectric methods, including airborne‐electromagnetics, have been applied in reconnaissance surveys. This paper summarizes the results of gravity surveys conducted across four Pleistocene valleys in northern Germany. Each buried valley causes a significant gravity anomaly. The observed anomalies in the residual gravity field range from −0.5 mGal to 0.7 mGal. The Ellerbek valley in Schleswig‐Holstein is the only buried valley causing a negative anomaly. Its infill is dominated by sandy sediments. Two other Pleistocene valleys in Schleswig‐Holstein, the Trave valley and the Curau valley, are filled with boulder clay. Both cause positive anomalies in the residual gravity field. In the area of the Bremerhaven‐Cuxhaven valley in Lower Saxony, a 4‐km2 survey area shows a quite different situation. Strong negative anomalies caused by shallow silt/clay layers are superimposed on positive anomalies caused by the valley sediments, resulting in a complicated pattern of gravity anomalies. The horizontal gravity gradient proved to be appropriate for locating the edges of the valleys.The quality of the gravity results was confirmed by the seismic data. Quantitative interpretations of the residual gravity anomalies, which give deeper insight into the structure of the valley fill, often suffer from a lack of information about the rock density. This lack of information can be partly compensated for by converting seismic velocities into densities, although in some cases the normally used velocity‐density formulae yield unrealistic density values. Nevertheless, the additional information obtained from gravity surveys can support the seismic interpretation or provide information in areas where other geophysical methods fail.

Ground surface temperature (GST), active layer and permafrost monitoring in continental Antarctica

Active layer and permafrost monitoring at two sites in Northern Victoria Land, Boulder Clay (74°44′45′′S—164°01′17′′E at 205 m a.s.l.) and Oasi (74°42′S—164°06′E at 80 m a.s.l.), have been undertaken since 1996. Active layer monitoring was performed at Boulder Clay by probing on a 100×100 m grid following the CALM protocol, and by temperature measurements to ascertain the maximum depth of the 0°C isotherm. Automatic and year-round recording of ground temperatures and of the main climatic parameters was carried out near the grid. Since 1999, ground temperatures have been monitored in a 15.5 m borehole at Oasi. The depth of the 0°C isotherm correlates well with climate because the thermal offset is small, averaging less than 0.5°C. The large spatial and temporal variability of its depth mainly reflects the snow accumulation pattern. Future efforts to extend the monitoring network in continental Antarctica may combine annual measurements of the maximum 0°C isotherm depth with year-round monitoring of ground temperature at selected points of standardised CALM grids. Copyright © 2006 John Wiley & Sons, Ltd.

The engineering geology and characterization of Dublin Boulder Clay

The ground investigation and construction for the North Cut and Cover Section of the Dublin Port Tunnel (north Dublin, Co. Dublin, Ireland) involved high resolution ground investigation and excavation logging. As a result, our interpretation of the glacially derived Quaternary geology encountered presents a more complex picture than previously described. A detailed description of the stratigraphy and lithology of the glacial deposits formerly known as the ‘Dublin Boulder Clay’ is presented, and palaeoenvironmental interpretations are suggested for the various units. The ‘Dublin Boulder Clay’ is reinterpreted to comprise four major units and associated subunits. Possible construction hazards, including discontinuities, lithological variability, glacio-tectonic rafting and the presence of large water-bearing units, are identified and linked with the stratigraphy. Preliminary data on the geotechnical and engineering behaviour of each unit are presented. The encountered lithologies generally demonstrated high in-situ strength and stiffness but low permeability and plasticity.

Dublin Port Tunnel – excavation of an 11.8 m diameter urban motorway tunnel

Every year more than 2,000,000 heavy goods vehicles pass through Dublin Port. The vehicles contribute to serious traffic congestion in the city centre of Dublin. The Dublin Port Tunnel was planned to connect Dublin Port to the M1 Motorway in the north of the city and remove a predicted 9000 vehicles a day from the centre. The twin tube road tunnel will be approximately 4.5 km long with each tube having two lanes of carriageway. Sections of the tunnel at the north and south were constructed by cut and cover methods with the central 2.6 km of route being constructed by bored tunnelling methods. The central section passed under a large number of residential properties. The NMI Consortium was awarded the design and build contract in December 2000. The consortium consisted of Nishimatsu, Mowlem and Irishenco. Nishimatsu were responsible for the design and construction of all the civil works related to the bored tunnels. The geology along the tunnel alignment consisted of approximately 500 m of Dublin Boulder Clay with the remaining section in the Dublin Formation that comprised carboniferous limestone with inter bedded shales. The predicted geology, worksite availability, contract programme and environmental requirements led to the selection by Nishimatsu of two different 11.8 m diameter TBMs. A hard rock TBM excavated two 2.2 km drives mainly within the Dublin Formation. The second machine was an Open-Face type TBM equipped with two intermediate decks and three excavator arms and excavated two short 330 m drives in boulder clay. Both machines were refurbished and supplied by Herrenknecht. Both tunnels were lined with a structural concrete segmental primary lining and an in situ concrete secondary lining containing polypropylene fibres. The precast concrete linings consisted of six segments and a key. The lining utilised hydrophilic gaskets. A number of tests were conducted to demonstrate the designed cruciform joints could be adequately sealed. The secondary lining provided fire resistance to the primary lining and a smooth finish for painting, luminescence and cleaning. The contract specified a fire resistance period to a modified hydrocarbon fire curve and full-scale fire tests were carried out to demonstrate compliance at TNO in the Netherlands. The tunnels pass under a large number of residential properties. During tunnel construction ground borne vibration, regenerated noise and settlement would occur. Extensive predictions and assessments were undertaken in advance of construction. A research project was initiated on these aspects that continued as the construction work progressed. The settlement, vibration and noise were continually monitored reviewed and analysed. (A). Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.