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Origin, Usage and Production of Unbound Granular Materials for Road Construction
Published in A. Gomes Correia, Fernando E.F. Branco, Bearing Capacity of Roads, Railways and Airfields, 2020
G. Bjarnason, H.G. Johansson, S. Davitt
The most characteristic and widespread material deposited directly from glaciers is glacial till. Till is a heterogeneous mixture of fragments of rock with grain sizes ranging from clay to boulders. Different types of till cover dominate large areas of former glaciated regions. Sometimes till is used in the production of aggregates. When the grain sizes are too fine the till has to be wet-sieved in order to remove the particles smaller in diameter than sand. However it is generally only economically worth exploiting the coarse-grained till varieties, consisting of pebbles, cobbles and gravel. Completely different and more important sediments for exploitation have been deposited by meltwater from the glacial ice sheet. These are glaciofluvial sediments that are well-sorted and accumulated in stratigraphical units. The sediments often occur in typical landforms.
Interpreting properties of glacial till from CPT and its accuracy in determining soil behaviour type when applying it to pile driveability assessments
Published in Michael A. Hicks, Federico Pisanò, Joek Peuchen, Cone Penetration Testing 2018, 2018
A. Cardoso, S. Raymackers, J. Davidson, S. Meissl
Glacial till is composed of unsorted material that has been carried out and deposited directly by a glacier. Due the heterogeneity of its composition (clay, silt, sand, gravel, cobbles and even boulders) the classification, and therefore, the behaviour prediction, can be very difficult. An interpretation of the site investigation data was carried out as a basis for the driveability assessment of the monopiles used as foundations of the windfarm. To assess the soil resistance to driving (SRD), the interpretation was based mainly on the CPT results. Borehole descriptions and laboratory tests are also taken into consideration. Driveability back-calculations were performed which showed that interpreting soil properties from CPT results should be treated with more value than borehole descriptions, when assessing soil resistance to driving in Swarte Bank glacial till.
Vadose Zone Hydrogeology in the United States
Published in L.G. Wilson, Lorne G. Everett, Stephen J. Cullen, Handbook of Vadose Zone Characterization & Monitoring, 2018
The second most extensive and almost continuous body of nonindurated sediments in the United States is made up of till and other closely associated glacial deposits which blanket the northern Midwest and extend eastward into New York and the New England states (Figure 3.5) (Heath, 1988). Till, in general, has a very low hydraulic conductivity, so subsurface drainage is poor. The vadose zone in extensive till plains under natural conditions is rarely more than 20 m thick and is commonly less than 5 m thick. Because of high water tables in many till plains, drainage ditches and tile drains are required to provide a vadose zone of sufficient thickness for general agriculture. Along margins of modern valleys and in terminal moraines, fractures induced by weathering (Williams and Farvolden, 1967) of the till together with lenses of sand and gravel in the till may provide enough permeability to effectively drain the sediments and thereby increase the vadose zone thickness to more than 20 m.
Development of training image database for subsurface stratigraphy
Published in Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2023
In comparison, lacustrine/marine origin often involves with still water and consists of uniform silts and clays with predominantly flat lying soil layer boundaries. Moreover, glaciers and wind are two natural drives in shaping the subsurface geology. Glacial till produced through glacial movements are very distinctive, containing clay matrix with scattered boulders, gravels and sands. While wind-formed dunes and loess are very homogeneous and predominantly made up of uniformly grain-sized sands and silts. With respect to downslope movements, the three resulted deposits (i.e. talus, colluvium and landslide debris) normally consist of random mixture of materials (e.g. rocks and soils), which are unstratified. Another two frequently encountered geological origins are organic and weathering. The former is mainly made up of organic materials with high water table and may be weakly stratified, while the geological textures of the latter depend upon rock type, and associated decomposition level exhibits a reducing trend with an increasing depth. Although geological origin plays a governing role in determining subsurface stratigraphy, the detailed stratigraphic characteristics are also influenced by natural environments at a specific location, as described in the next subsection.
Erosional and depositional subglacial streamlining processes at Skálafellsjökull, Iceland: an analogue for a new bedform continuum model
Published in GFF, 2018
Jane K. Hart, Alexander I. Clayton, Kirk Martinez, Benjamin A. Robson
This research (and the other related studies in Table 5) extends the previous large scale study by Hart (1997) into the examination of smaller bedforms. From these it is proposed that simultaneous deposition and erosion produces the full range of bedforms from flutes to drumlins. However, it is stressed that all these form due to a negative sediment flux (i.e., more sediment is removed from a given subglacial area than enters). Where there is a positive flux (i.e., more sediment enters a given subglacial area than is removed) there will be a net build up (deposition) of till.
A method to assess the suffusion susceptibility of low permeability core soils in compacted dams based on construction data
Published in European Journal of Environmental and Civil Engineering, 2019
Lingran Zhang, Rachel Gelet, Didier Marot, Marc Smith, Jean-Marie Konrad
The central impervious core is made of compacted, low plasticity glacial till from Northern Québec. The till is generally a well-graded soil (the maximum particle size is up to 300 mm). The grain size distribution generally becomes coarser from the central core to the rockfill. The glacial till used to build the dam core comes from a preselected nearby borrow pit. The placement of the till was realised by dumping and spreading the material in lifts across the entire width of the core.