Geology, mineralogy, and geochemistry of Canadian soft soils: a geotechnical perspective

1980 ◽  
Vol 17 (2) ◽  
pp. 261-285 ◽  
Author(s):  
Robert M. Quigley
Keyword(s):  
Soft Soil ◽  
Three Dimensional ◽  
Research Literature ◽  
Low Density ◽  
Soft Soils ◽  
Soft Clays ◽  
Clay Deposits ◽  
Soil Sensitivity ◽  
Dimensional Distribution ◽  
Marine Clays

A review of the recent research literature concerning the geology, mineralogy, and physicochemistry of soft soils in Canada is presented. Soft clays are considered from three viewpoints: (1) their three-dimensional distribution and chronological evolution, (2) the sedimentological processes critical in their formation, and (3) geochemistry and mineralogy as they directly influence geotechnical behaviour, especially soft soil sensitivity.Canada's soft soils are products of sedimentation in proglacial and postglacial lake basins that existed between 18 000 and 6000 years BP. They consist of both freshwater and marine clays, which usually behave quite differently, due to peptization or dispersion of the marine clays following postglacial crustal rebound that elevated all clay deposits. The evolution of the major lakes and seas is briefly reviewed in a Canada-wide context.The sedimentology review shows clearly that varved clays are normally features of bottom, heavy-density turbidity current origin, probably in very cold, ice-contact glacial lakes. Warmer postglacial lakes were probably characterized by low-density overflows, and thinly laminated clay deposits developed rather than varved clay sequences. Marine clay deposits also developed from low-density freshwater overflows followed by flocculation, organic agglomeration, and sedimentation. Modern examples are given to illustrate the three major sedimentological processes.Mineralogy and physicochemistry are reviewed in terms of their practical relevance to soft soil sensitivity. Factors influencing both the undisturbed strength and the remoulded strength are reviewed with special reference to recent Canadian research. Included are discussions of cementing agents, specific surface, amorphous and smectite contents, and zeta potential controls as they influence depositional flocculation and postdepositional peptization.

scholarly journals Preloading system with partially penetrating vertical drains in marine soft clays in Egypt: 2D and 3D comparative FE study

2021 ◽  
Vol 13 (3) ◽  
pp. 10-22
Author(s):  
Ahmed M. Abouhashem ◽  
Alaa El-Din A. El-Gendy ◽  
Mohamed H. Rabie ◽  
Mohamed A. Mostafa
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Design Parameters ◽  
Marine Clay ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Soft Clays ◽  
Clay Deposits ◽  
Three Dimensional Finite Element

A large-scale trial embankment provided with partially penetrating prefabricated vertical drains (PVD) was installed in consolidating marine clay deposits at East-Port said industrial zone project in Egypt. The trial embankment was constructed with a bottom area of 150x150m and a height of 5.5m to evaluate the efficiency of the improvement system and verify the design parameters. An intensive instrumentation system was built-up including shallow settlement indicators, vibrating wire piezometers, extensometer, and inclinometers. Two and three-dimensional finite element analyses (FE) were performed to study the effect of the preloading system provided with partially PVD in consolidating marine clay deposits. FE models were validated and showed good agreement with the field observations in terms of vertical displacement of embankment center, and lateral soil deformation beneath the embankment toe.

scholarly journals Analysis of Embankment Supported by Rigid Inclusions Using Plaxis 3D

2021 ◽  
Author(s):  
Rashad Alsirawan
Keyword(s):  
Rigid Inclusion ◽  
Load Transfer ◽  
Soft Soil ◽  
Three Dimensional ◽  
Field Measurements ◽  
Soil Arching ◽  
Element Analysis ◽  
Soft Soils ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

A rigid inclusion-supported embankment is used to overcome the problems of soft soils. This system is considered complex due to the various interactions between its elements, namely the embankment body, load transfer platform, geogrid layers, piles, and soft soils. The load transfer mechanism is based on the phenomenon of soil arching, the tension in the geogrid layers, support of the soft soils, and friction between piles and soft soil. In this paper, the first part highlights the behaviour of a rigid inclusion-supported embankment validated by field measurements, and the contribution of rigid inclusions technology to the reduction of settlement and creep settlement. In addition, the effect of geogrid in improving the load efficiency and reducing the settlements is presented. In the second part, a comparison is made between many analytical design methods and a three-dimensional finite element analysis method. The results show the inconsistencies between the analytical methods in calculating the load efficiency and the tension in the geogrid.

Three-dimensional distribution of ribulose-1, 5-bisphosphate carboxylase/oxygemase during the early development of proplastids in dark-grown Euglena cells transferred to an inorganic medium

1990 ◽  
Vol 48 (3) ◽  
pp. 906-907
Author(s):  
Tomoko Ehara ◽  
Shuji Sumida ◽  
Tetsuaki Osafune ◽  
Eiji Hase
Keyword(s):  
Cell Suspension ◽  
Euglena Gracilis ◽  
Carbon Materials ◽  
Three Dimensional ◽  
Peripheral Region ◽  
Plastid Development ◽  
Bisphosphate Carboxylase ◽  
Inorganic Medium ◽  
Ribulose 1 ◽  
Dimensional Distribution

As shown previously, Euglena cells grown in Hutner’s medium in the dark without agitation accumulate wax as well as paramylum, and contain proplastids showing no internal structure except for a single prothylakoid existing close to the envelope. When the cells are transferred to an inorganic medium containing ammonium salt and the cell suspension is aerated in the dark, the wax was oxidatively metabolized, providing carbon materials and energy 23 for some dark processes of plastid development. Under these conditions, pyrenoid-like structures (called “pro-pyrenoids”) are formed at the sites adjacent to the prolamel larbodies (PLB) localized in the peripheral region of the proplastid. The single prothylakoid becomes paired with a newly formed prothylakoid, and a part of the paired prothylakoids is extended, with foldings, in to the “propyrenoid”. In this study, we observed a concentration of RuBisCO in the “propyrenoid” of Euglena gracilis strain Z using immunoelectron microscopy.

ANALYZING THE THREE-DIMENSIONAL DISTRIBUTION OF A SHALLOW-MARINE BONEBED IN THE LOWER HORNERSTOWN FORMATION AT EDELMAN FOSSIL PARK, NJ

2020 ◽  
Author(s):  
Tara Lonsdorf ◽  
◽  
Kristyn Voegele ◽  
Zachary Christman
Keyword(s):  
Three Dimensional ◽  
Shallow Marine ◽  
Dimensional Distribution

ANALYZING THE THREE-DIMENSIONAL DISTRIBUTION OF A SHALLOW-MARINE BONEBED IN THE LOWER HORNERSTOWN FORMATION AT EDELMAN FOSSIL PARK, NJ

2020 ◽  
Author(s):  
Tara Lonsdorf ◽  
◽  
Kristyn K. Voegele ◽  
Zachary Christman
Keyword(s):  
Three Dimensional ◽  
Shallow Marine ◽  
Dimensional Distribution

scholarly journals Dip angles of active faults from the surface to the seismogenic zone inferred from a 2D numerical analysis of visco-elasto-plastic models: a case study for the Osaka Plain

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hayami Nishiwaki ◽  
Takamoto Okudaira ◽  
Kazuhiko Ishii ◽  
Muneki Mitamura
Keyword(s):  
Urban Areas ◽  
Active Faults ◽  
Three Dimensional ◽  
Seismogenic Zone ◽  
Earthquake Ground Motion ◽  
Convex Curve ◽  
Seismic Reflection Profile ◽  
Geological Structures ◽  
Dimensional Distribution ◽  
Dip Angle

AbstractThe geometries (i.e., dip angles) of active faults from the surface to the seismogenic zone are the most important factors used to evaluate earthquake ground motion, which is crucial for seismic hazard assessments in urban areas. In Osaka, a metropolitan city in Japan, there are several active faults (e.g., the Uemachi and Ikoma faults), which are inferred from the topography, the attitude of active faults in surface trenches, the seismic reflection profile at shallow depths (less than 2 km), and the three-dimensional distribution of the Quaternary sedimentary layers. The Uemachi and Ikoma faults are N–S-striking fault systems with total lengths of 42 km and 38 km, respectively, with the former being located ~ 12 km west of the latter; however, the geometries of each of the active faults within the seismogenic zone are not clear. In this study, to examine the geometries of the Uemachi and Ikoma faults from the surface to the seismogenic zone, we analyze the development of the geological structures of sedimentary layers based on numerical simulations of a two-dimensional visco-elasto-plastic body under a horizontal compressive stress field, including preexisting high-strained weak zones (i.e., faults) and surface sedimentation processes, and evaluate the relationship between the observed geological structures of the Quaternary sediments (i.e., the Osaka Group) in the Osaka Plain and the model results. As a result, we propose geometries of the Uemachi and Ikoma faults from the surface to the seismogenic zone. When the friction coefficient of the faults is ~ 0.5, the dip angles of the Uemachi and Ikoma faults near the surface are ~ 30°–40° and the Uemachi fault has a downward convex curve at the bottom of the seismogenic zone, but does not converge to the Ikoma fault. Based on the analysis in this study, the dip angle of the Uemachi fault zone is estimated to be approximately 30°–40°, which is lower than that estimated in the previous studies. If the active fault has a low angle, the width of the fault plane is long, and thus the estimated seismic moment will be large.

scholarly journals Simulation and measurement of air quality in the traffic congestion area

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Shin Yu ◽  
Chang Tang Chang ◽  
Chih Ming Ma
Keyword(s):  
Air Quality ◽  
Traffic Congestion ◽  
Traffic Management ◽  
Reference Model ◽  
Dispersion Model ◽  
Fluid Model ◽  
Three Dimensional ◽  
Vehicle Speed ◽  
Management Plans ◽  
Dimensional Distribution

AbstractThe traffic congestion in the Hsuehshan tunnel and at the Toucheng interchange has led to traffic-related air pollution with increasing concern. To ensure the authenticity of our simulation, the concentration of the last 150 m in Hsuehshan tunnel was simulated using the computational fluid dynamics fluid model. The air quality at the Toucheng interchange along a 2 km length highway was simulated using the California Line Source Dispersion Model. The differences in air quality between rush hours and normal traffic conditions were also investigated. An unmanned aerial vehicle (UAV) with installed PM2.5 sensors was developed to obtain the three-dimensional distribution of pollutants. On different roads, during the weekend, the concentrations of pollutants such as SOx, CO, NO, and PM2.5 were observed to be in the range of 0.003–0.008, 7.5–15, 1.5–2.5 ppm, and 40–80 μg m− 3, respectively. On weekdays, the vehicle speed and the natural wind were 60 km h− 1 and 2.0 m s− 1, respectively. On weekdays, the SOx, CO, NO, and PM2.5 concentrations were found to be in the range of 0.002–0.003, 3–9, 0.7–1.8 ppm, and 35–50 μg m− 3, respectively. The UAV was used to verify that the PM2.5 concentrations of vertical changes at heights of 9.0, 7.0, 5.0, and 3.0 m were 45–48, 30–35, 25–30, and 50–52 μg m− 3, respectively. In addition, the predicted PM2.5 concentrations were 40–45, 25–30, 45–48, and 45–50 μg m− 3 on weekdays. These results provide a reference model for environmental impact assessments of long tunnels and traffic jam-prone areas. These models and data are useful for transportation planners in the context of creating traffic management plans.

scholarly journals Three-dimensional distribution of CT attenuation in the lumbar spine pedicle wall

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomoyo Y. Irie ◽  
Tohru Irie ◽  
Alejandro A. Espinoza Orías ◽  
Kazuyuki Segami ◽  
Norimasa Iwasaki ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Age Groups ◽  
Three Dimensional ◽  
Hounsfield Unit ◽  
Lateral Wall ◽  
Ct Attenuation ◽  
Dimensional Distribution ◽  
The Mean ◽  
Pedicle Wall

AbstractThis study investigated in vivo the three-dimensional distribution of CT attenuation in the lumbar spine pedicle wall measured in Hounsfield Unit (HU). Seventy-five volunteers underwent clinical lumbar spine CT scans. Data was analyzed with custom-written software to determine the regional variation in pedicle wall attenuation values. A cylindrical coordinate system oriented along the pedicle’s long axis was used to calculate the pedicular wall attenuation distribution three-dimensionally and the highest attenuation value was identified. The pedicular cross-section was divided into four quadrants: lateral, medial, cranial, and caudal. The mean HU value for each quadrant was calculated for all lumbar spine levels (L1–5). The pedicle wall attenuation was analyzed by gender, age, spinal levels and anatomical quadrant. The mean HU values of the pedicle wall at L1 and L5 were significantly lower than the values between L2–4 in both genders and in both age groups. Furthermore, the medial quadrant showed higher HU values than the lateral quadrant at all levels and the caudal quadrant showed higher HU values at L1–3 and lower HU values at L4–5 than the cranial quadrant. These findings may explain why there is a higher incidence of pedicle screw breach in the pedicle lateral wall.

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