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Seismic design of structures
Published in Ömer Aydan, Earthquake Science and Engineering, 2023
Embankments are simple geotechnical structures used along river banks, roadways and railway lines as illustrated in Figure 8.34, and they are constructed by banking soil. The compaction of the embankment during construction differs depending upon the importance of the structure and there may be some special treatment of the interface between the existing ground and embankment body. If there is no special treatment of the interface, it may be quite critical during earthquakes where high excess pore pressure may develop and it may lead to the failure of embankment. There are methods for analysing the stability of embankments, such as the pseudo-dynamic method based on the seismic coefficient concept, pure dynamic limiting equilibrium method (DLEM) and numerical techniques. In this section, the available methods and their principles are outlined.
Design considerations
Published in Burt G. Look, Earthworks, 2023
Soft compressible soils (clays, organic silts, and peats) may be unstable. Stability is dependent on the height of the embankment and the thickness and depth of layer. Embankment stability and settlement issues must be considered. Stability and settlement are often interrelated and time-dependent. When a soft foundation is present, the FS decreases as load is placed (Figure 13.6-1). In the long term, the FS increases. Short-term conditions, therefore, determine the stability.
Application
Published in Andrew Braham, Sadie Casillas, Fundamentals of Sustainability in Civil Engineering, 2020
Embankment refers to placing and compacting materials to raise the existing grade above the level of surrounding ground surface, usually for a roadway, a railway, or the area under a building pad. Fill refers to placing and compacting material in a depression or hole, or the leveling of an existing site for preparation of a slab on grade foundation. When considering fill under a pavement structure, generally coarser and lower-quality material is placed at the bottom to provide a firm foundation and drainage, while the top portions are well-compacted with high-quality material that can support the structure being constructed directly above. However, fill under a building foundation is not as straight forward. Depending on the depth of the fill, the lower materials may need to be just as highly controlled as the upper materials or the foundation bearing capacity and settlement design will be compromised. Important properties of alternate granular fill materials include gradation, unit weight/specific gravity, moisture-density characteristics (optimal moisture content, maximum dry density), shear strength (cohesion, internal friction), and compressibility (consolidation, settlement). Of these properties, the gradation is the only property that can be influenced, by crushing, screening, or washing.
Strategies for flood risk reduction in India
Published in ISH Journal of Hydraulic Engineering, 2023
Sharad K. Jain, Vijay P. Singh
Embankments confine flood flows and prevent spilling thereby reducing damage. Embankments are old and tested methods of flood control that have been very successful in many countries in keeping flood waters away from the area to be protected, e.g. the Netherlands. In India, about 35,200 km of embankments had been constructed by year 2015 (Marchand et al. 2015) to prevent flood submergence. Embankments are generally cheap, quick to construct, and have been widely constructed in the past. They provide considerable protection at comparatively low costs, particularly in the lower reaches of large rivers and help reduce h, and of Equation (3). In many places, where control of flood inundation by any other means is not possible, embankments may be the only feasible method of preventing inundation. Marchand et al. (2015) found that by providing 25-year return period flood protection, about 90% of the average annual damage could be avoided in the Brahamai-Baitarni basins.
A case study of a dcm column-supported embankment over soft clay
Published in International Journal of Geotechnical Engineering, 2022
Embankments are widely used to provide an elevated platform for roads, railways, and runways. When they are constructed over soft clays or organic type weak soils with high compressibility and low shear strength characteristics, extremely large settlements and instability problems are inevitable. To overcome these problems, a wide range of ground improvement technologies have been developed aiming to improve the bearing capacity and settlement characteristics of the soft ground. Although methods based on consolidation are available for the soil to gain strength and stiffness over a long time, it is often not economical due to the uncertainties associated with soil conditions, time restrictions associated with the delivery of projects, and considerable settlement around the area, which may cause damages to adjacent facilities. Consequently, DCM columns are introduced as a fast track and an economical ground stabilization method to bypass the disadvantages associated with conventional consolidation-based ground improvement techniques.
Development of fragility curves for road embankments exposed to perpendicular debris flows
Published in Geomatics, Natural Hazards and Risk, 2021
Natalia Nieto, Alondra Chamorro, Tomás Echaveguren, Esteban Sáez, Alvaro González
A road embankment is a volume of earth laid and compacted over the natural soil, raising the level of a road to improve geometric and structural characteristics. It consists of three parts, described bottom-up: base of the embankment, core corresponding to the central body, and the crown or surface. The embankment core is commonly designed with relatively homogeneous non-cohesive granular soil (Wu et al. 2012). The height of the embankment depends on several factors such as design, location, and functionality. However, to simplify the analysis and based on the experience of the authors, embankments with heights from 1 m to 6 m will be considered in this study. As can be seen in Figure 1, some conditions are activated once the height of the flow exceeds the height of the embankment. Therefore, to consider these effects in the models, it is decided to discretize in 3 ranges of embankment height, 1–2.5 m, 2.5–4 m, and 4–6 m. This division tried to group embankments that behaved similarly, in addition to not losing practicality in the analysis.