Geotechnical Properties of Nearshore Sediments of Canso Strait, Nova Scotia

1975 ◽  
Vol 12 (1) ◽  
pp. 44-57 ◽  
Author(s):  
J. D. Brown ◽  
M. A. Rashid
Keyword(s):  
Nova Scotia ◽  
Geotechnical Properties ◽  
Coarse Grained ◽  
Gravity Corer ◽  
Near Surface ◽  
Fine Grained ◽  
Lehigh University ◽  
Overconsolidated Clays ◽  
Nearshore Sediments

The results are reported of a field and laboratory investigation of the geotechnical properties of the surficial bottom, or near-surface, sediments of the Strait of Canso, Nova Scotia. The investigation procedures included in situ shear vane tests performed using a diver-operated apparatus lowered to the bottom from the survey ship, and undisturbed sampling using the Lehigh University Gravity Corer, which provides a 10 cm diameter sample.Soils encountered within the sampling depth (0–1.5 m maximum) consisted of layered and bioturbated coarse-grained and fine-grained sediments. Most of the investigative work was concerned with the fine-grained sediments, clayey silts, and clays, which were found to be soft and compressible, but possessed a reserve resistance in both shear and one-dimensional consolidation which give them the characteristics of overconsolidated clays. This reserve resistance has been attributed to chemical alteration, including the effects of organic compounds.

The relationship between sedimentary facies and faunal associations in the Llandovery siliciclastic Ross Brook Formation, Arisaig, Nova Scotia

1986 ◽  
Vol 23 (5) ◽  
pp. 705-726 ◽  
Author(s):  
J. M. Hurst ◽  
R. K. Pickerill
Keyword(s):  
Nova Scotia ◽  
Environmental Parameters ◽  
Sedimentary Facies ◽  
Great Distance ◽  
Thin Layers ◽  
Coarse Grained ◽  
Individual Species ◽  
Silty Mudstone ◽  
Evolutionary Pattern ◽  
Fine Grained

The Llandovery siliciclastic Ross Brook Formation of Arisaig, Nova Scotia, comprises three broadly defined sedimentary facies. These are a mottled silty mudstone facies (facies A), a laminated shale facies (facies B), and a laminated siltstone facies (facies C). Facies A consists of variably bioturbated silty mudstones, muddy siltstones, and fissile shales. It developed in relatively shallow water conditions; mudstones were presumably deposited from suspension, and siltstone laminae and thin layers were formed by increased wave and current activity. Mottling resulted from bioturbation by epifaunal and, particularly, infaunal benthic organisms. Within facies A, two subfacies are recognized: A(i) is mudstone dominated, and A(ii) is fine-grained siltstone dominated. Facies B consists of alternating laminae of undisturbed mudstone and fine-grained siltstone probably produced as a result of deposition from suspension during a temporary upward expansion of the oxygen-minimum layer. Facies C consists of 0.5–30 cm thick fine- to coarse-grained siltstones, which occur in lenses or layers of single, composite, or amalgamated units. Internally they are extremely variable, but all are interpreted as a result of deposition from storm-generated currents.The Ross Brook Formation formed on a shallow-marine, storm-influenced, subtidal inner–mid muddy shelf and is dominated by extensive but stratigraphically variable developments of facies A and facies C. Absolute water depth per se is difficult to assess, and although fluctuations occurred, much of the sequence is believed to have accumulated at or in the immediate vicinity of fair-weather wave base in water depths estimated to have been between 30 and 60 m. Silt supply was generally low, possibly reflecting great distance from source or the presence of a mud-dominated shoreline.Five brachiopod-dominated associations, which are stratigraphically the Eocoelia hemisphaerica, the Eocoelia intermedia – Eocoelia curtisi, the Visbyella nana, the "Camarotoechia" rossonia, and the Eocoelia sulcata associations, occur through the sequence. Associations change where die sum of the facies characteristics change, suggesting that the major physical controlling factor was substrate type and related environmental parameters. The development of discrete but intergrading associations is viewed as a consequence of the long-term persistence of a set of conservative animal–sediment relationships, superimposed on which is the evolutionary pattern of immigration and extinction of individual species.

Combined In Situ Neutron Diffraction and Acoustic Emission of Twin Nucleation & Twin Growth in Extruded ZM20 Mg Alloy

2010 ◽  
Vol 652 ◽  
pp. 149-154 ◽  
Author(s):  
Ondrej Muránsky ◽  
Matthew R. Barnett ◽  
David G. Carr ◽  
Sven C. Vogel ◽  
E.C. Oliver
Keyword(s):  
Acoustic Emission ◽  
Neutron Diffraction ◽  
Room Temperature ◽  
Coarse Grained ◽  
Fine Grained ◽  
Grain Sizes ◽  
Twin Nucleation ◽  
Twin Growth ◽  
In Situ Neutron Diffraction

In the present work in situ neutron diffraction and acoustic emission were used concurrently to study deformation twinning in two ZM20 Mg alloys with significantly different grain sizes at room temperature. The combination of these techniques allows differentionation between the twin nucleation and the twin growth mechanisms. It is shown, that yielding and immediate post-yielding plasticity in compression is governed primarily by twin nucleation, whereas the plasticity at higher strains is governed by twin growth. The current results further suggest that yielding by twinning happens in a slightly different manner in the fine-grained as compared to the coarse-grained alloy.

scholarly journals Ground-Penetrating Radar Evaluation of Moisture and Frost across Typical Saskatchewan Road Soils

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Curtis Berthelot ◽  
Diana Podborochynski ◽  
Timo Saarenketo ◽  
Brent Marjerison ◽  
Colin Prang
Keyword(s):  
Dielectric Constant ◽  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Soil Type ◽  
Structural Condition ◽  
Coarse Grained ◽  
Fine Grained ◽  
Survey Results ◽  
Ground Penetrating

This study was undertaken to evaluate the effect of soil type, moisture content, and the presence of frost on road substructure permittivity. Permittivity sensitivity of typical road soils was characterized in the laboratory to provide baseline dielectric constant values which were compared to field ground penetrating radar (GPR) survey results. Both laboratory devices, the complex dielectric network analyzer and the Adek Percometer, as well as the field GPR system were used in this study to measure the dielectric constant of soils. All three systems differentiated between coarse-grained and fine grained soils. In addition, at temperatures below freezing, all three systems identified an increase in water content in soils; however, when frozen, the sensitivity of dielectric constant across soil type and moisture content was significantly reduced. Based on the findings of this study, GPR technology has the ability to characterize in situ substructure soil type and moisture content of typical Saskatchewan road substructure soils. Given the influence of road soil type and moisture content on in-service road performance, this ability could provide road engineers with accurate estimates of in situ structural condition of road structures for preservation and rehabilitation planning and optimization purposes.

scholarly journals The Challenge of Spatial Resolutions for GRACE-Based Estimates Volume Changes of Larger Man-Made Lake: The Case of China’s Three Gorges Reservoir in the Yangtze River

2019 ◽  
Vol 11 (1) ◽  
pp. 99 ◽  
Author(s):  
Linsong Wang ◽  
Mikhail K. Kaban ◽  
Maik Thomas ◽  
Chao Chen ◽  
Xian Ma
Keyword(s):  
Volume Change ◽  
Land Surface ◽  
Three Gorges Reservoir ◽  
Water Storage ◽  
In Situ Measurements ◽  
Coarse Grained ◽  
Three Gorges ◽  
Volume Changes ◽  
Near Surface

The Three Gorges Reservoir (TGR) in China, with the largest dam in the world, stores a large volume of water and may influence the Earth’s gravity field on sub-seasonal to interannual timescales. Significant changes of the total water storage (TWS) might be detectable by satellite-based data provided by the Gravity Recovery and Climate Experiment (GRACE) mission. To detect these store water changes, effects of other factors are to be removed first from these data due to band-limited representation of near-surface mass changes from GRACE. Here, we evaluated three current popular land surface models (LSMs) basing on in situ measurements and found that the WaterGAP Global Hydrology Model (WGHM) demonstrates higher correlation than other analyzed models with the in-situ rainfall measurement. Then we used the WGHM outputs to remove climate-induced TWS changes, such as surface water storage, soil, canopy, snow, and groundwater storage. The residual results (GRACE minus WGHM) indicated a strong trend (3.85 ± 2 km3/yr) that is significantly higher than the TGR analysis and hindcast experiments (2.29 ± 1 km3/yr) based on in-situ water level measurements. We also estimated the seepage response to the TGR filling, contributions from other anthropogenic dams, and used in-situ gravity and GPS observations to evaluate dominant factors responsible for the GRACE-based overestimate of the TGR volume change. We found that the modeled seepage variability through coarse-grained materials explained most of the difference between the GRACE based estimate of TGR volume changes and in situ measurements, but the agreement with in-situ gravity observations is considerably lower. In contrast, the leakage contribution from 13 adjacent reservoirs explained ~74% of the TGR volume change derived from GRACE and WGHM. Our results demonstrate that GRACE-based overestimate TGR mass change mainly from the contribution of surrounding artificial reservoirs and underestimated TWS variations in WGHM simulations due to the large uncertainty of WGHM in groundwater component. In additional, this study also indicates that reservoir or lake volume changes can be reliably derived from GRACE data when they are used in combination with relevant complementary observations.

In Situ Neutron Diffraction Study on the Mechanical Behavior of an Ultra-Fine-Grained Steel

2006 ◽  
Vol 524-525 ◽  
pp. 639-644 ◽  
Author(s):  
Kai Xiang Tao ◽  
Hahn Choo ◽  
H. Li ◽  
Bjørn Clausen ◽  
Donald W. Brown ◽  
...  
Keyword(s):  
Grain Size ◽  
Neutron Diffraction ◽  
High Strength ◽  
Neutron Diffraction Study ◽  
Coarse Grained ◽  
Transformation Induced Plasticity ◽  
Fine Grained ◽  
High Elongation ◽  
In Situ Neutron Diffraction

The martensitic phase transformation in an ultra fine grained (UFG) TRIP (transformation induced plasticity) steel with combination of high strength and high elongation was investigated during room temperature tensile test using in situ neutron diffraction. Two types of specimens, namely coarse grained (grain size of about 50 μm) and ultra-fine-grained (grain size of about 350 nm) specimens were examined. The lattice strain evolution of the austenite and martensite phases was observed and the load partitioning between the phases was identified.

An in‐hole shotgun source for engineering seismic surveys

Geophysics ◽  
1987 ◽  
Vol 52 (7) ◽  
pp. 985-996 ◽  
Author(s):  
S. E. Pullan ◽  
H. A. MacAulay
Keyword(s):  
Ground Surface ◽  
Seismic Source ◽  
Coarse Grained ◽  
Near Surface ◽  
Seismic Surveys ◽  
Fine Grained ◽  
Reflection Seismic ◽  
Weight Drop ◽  
Water Saturated ◽  
Excellent Source

We have conducted several source comparisons involving 12‐gauge and 8‐gauge Buffalo guns, a 7.3 kg sledgehammer, and a 75 kg weight drop. The results are strongly site‐dependent. We found that, when the near‐surface consisted of fine‐grained, water‐saturated sediments, the 12‐gauge Buffalo gun produced up to two orders of magnitude more energy than the conventional hammer across a broad frequency range. Under such conditions the gun produced the greatest improvement in energy between 200 and 400 Hz, where it yielded up to ten times more energy than the 75 kg weight drop. This indicates that the Buffalo gun may be particularly useful as a shallow reflection seismic source. However, at sites where the near‐surface materials were coarse‐grained and the water table was well below the ground surface, the advantages of using an in‐hole shotgun source as opposed to a hammer or weight drop were minimal. Nevertheless, in many areas we believe that the Buffalo gun is an excellent source for engineering seismic surveys. It is lightweight and portable (<5 kg), inexpensive to build (<$100 US), simple to use and maintain, and a good source of high‐frequency energy.

Cordierite in the peraluminous granites of the Meguma Zone, Nova Scotia, Canada

1985 ◽  
Vol 49 (354) ◽  
pp. 695-702 ◽  
Author(s):  
Lynne A. Maillet ◽  
D. Barrie Clarke
Keyword(s):  
Nova Scotia ◽  
Fluid Phase ◽  
Coarse Grained ◽  
Chemical Characteristics ◽  
Fine Grained ◽  
Peraluminous Granites ◽  
Granitoid Intrusions

AbstractThe peraluminous granitoid intrusions of southern Nova Scotia contain several mineralogical expressions of the excess alumina, including variable amounts of cordierite, in different textural types of granitoids, ranging from fine-grained aplites through coarser grained monzogranites and granodiorites, to very coarse-grained pegmatites. A detailed study of the spatial, textural and chemical characteristics of these cordierites suggests that the majority are of relict metamorphic origin, but that primary magmatic cordierites, as well as cordierites which grew in equilibrium with a water-rich fluid phase, also occur.

scholarly journals Microstructural evolution of fine-grained layers through the firn column at Summit, Greenland

2011 ◽  
Vol 57 (204) ◽  
pp. 755-762 ◽  
Author(s):  
R. Lomonaco ◽  
M. Albert ◽  
I. Baker
Keyword(s):  
Microstructural Characterization ◽  
Dust Particles ◽  
Near Surface ◽  
Fine Grained ◽  
Pole Figures ◽  
Microstructure Measurements ◽  
Electron Imaging ◽  
Lock In ◽  
Microscopy Techniques

AbstractWe present a microstructural characterization of fine-grained layers from the top 90 m of firn from Summit, Greenland, performed using a combination of scanning electron microscopy techniques including secondary electron imaging, energy-dispersive spectroscopy and electron backscattered patterns, and X-ray microcomputed tomography. The impurities in the firn, both soluble impurities and dust particles, were found largely in the grain interiors. Both c- and a-axis pole figures do not show strong evidence of a preferred orientation of the grains even at the bottom of the firn column. The firn structure became increasingly anisotropic with vertical alignment in the top 3 m, probably due to vapor transport associated with dry-snow metamorphism. The anisotropy decreases below this level until at ∼50 m the average firn structure is close to isotropic. In the near surface, the level of anisotropy is weaker than at Hercules Dome, Antarctica, confirming that differences in accumulation rates and temperatures leave enduring evidence in the structure of the firn. The fraction of closed-off pores is relatively low until ∼65 m; below that it rises through the end of our sampling at 90 m. Our microstructure measurements on the microscale are consistent with in situ firn-air sampling measurements on a decimeter scale, both indicating the existence of the lock-in zone starting near 69 m depth, and pore close-off at 81 m at this site.

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