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Basic Principles
Published in Kathleen Sellers, Fundamentals of Hazardous Waste Site Remediation, 2018
A layer of fill covers many sites in developed areas. Fill, which may comprise soil, ashes, and/or mixed debris, was placed at many sites to fill in a wetland and make usable land, to level natural ground contours, or to dispose of waste. Natural geologic formations include unconsolidated deposits and rocks. Unconsolidated deposits are soils originally deposited by glaciers, water (such as river sediments), or wind (such as sand dunes). Unconsolidated deposits include materials such as gravel, sand, silt, and clay. These materials are characterized by their particle size, as indicated in Table 2.6. Rock formations include consolidated sedimentary rocks such as sandstone, shale, and limestone, igneous rocks, and metamorphic rocks such as granite, basalt, slate, or gneiss.
Earth Systems and Cycles
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Sediments of all sorts are deposited on dry land, in lakes or streams, or on ocean bottoms. As gravity deposits new sediment on top of old sediment, thick sedimentary layers, up to thousands of meters thick, may form. Silt, sand, mud, gravel, soil, and biogenic debris such as seashells on a beach are some more common constituents. However, the nature of a sediment depends on the original parent material and on climatic factors, including temperature and precipitation, and on biological activity. Landscape and topography, too, affect the thickness and nature of sedimentary layers. The deposits remain sediments until they are consolidated and lithify (harden), at which point they become sedimentary rocks.
Strategic Issues in Environmental Remediation
Published in Timothy J. Havranek, Modern Project Management Techniques for the Environmental Remediation Industry, 2017
Subsurface earth materials can be placed into two broad classifications: unconsolidated materials and consolidated bedrock. In general, unconsolidated material refers to the loose soil materials which result from the erosion of bedrock. These loose materials include gravel, sand, silt, and clay. Previously excavated materials and construction debris can also be included in the category of unconsolidated materials. Consolidated bedrock includes (1) sedimentary rocks such as shale, sandstone, and limestone; (2) igneous rocks such as granite; and (3) metamorphic rocks such as slate and marble.
Prediction of compressibility and shear strength behaviour of in-situ cohesive soil from reconstituted clay
Published in International Journal of Geotechnical Engineering, 2022
Md. Kausar Alam, Naveel Islam, Md. Zoynul Abedin, Mohammad Shariful Islam, Rajib Dey, Arun J. Valsangkar
Figure 5 compares the void ratio against effective vertical stress from the one-dimensional consolidation test for UD and RʹNC samples from three different sites. Figure 5 shows the loading and unloading curve for maximum vertical stress of 800 kPa, similar to the maximum overburden pressure used to prepare the RʹC soil cake. Figure 5 was consolidated at maximum vertical stress of 1600 kPa even though the RʹC soil cakes were prepared for a maximum overburden pressure of 800 kPa. It is to note that, in Figure 5, reconstituted soil cake was normally consolidated state as the over consolidation ratio (OCR) was 1. To observe how reconstituted soil cake behaves in under consolidated state, reconstituted soil cake was applied 1600 kPa vertical stress (see Figure 5). Simultaneous tests on the UD clay samples from the three soil locations provide identical loading-unloading behaviour.
Formation mechanism of large pockmarks in the subaqueous Yellow River Delta
Published in Marine Georesources & Geotechnology, 2019
Zhuangcai Tian, Xiujun Guo, Luzheng Qiao, Le Yu, Guohui Xu, Tao Liu
After disruption, the sediments were redistributed under the influence of external hydrodynamics (e.g., current and waves). Some sediment in suspension was transported a long distance by the currents and wave action, but the majority of the sediment reconsolidated in situ. Shan et al. (2006) and Yang et al. (2010) conducted a simulation experiment that simulated the process at the shore of the Yellow River Estuary. The rate of sediment consolidation was related to the external hydrodynamic environment. With an increase in the depth, the role of the hydrodynamics decreased. The density of the sediment increased after consolidation, and the sediment strength was stronger than the undisturbed sediment strength. Seabed sediment is rapidly consolidated under the effects of its own weight. This characteristic matched the findings of the field investigation of the sediment characteristics of the sediment inside and outside the pockmark. These processes enable the seabed to develop negative topography after in situ reconsolidation, forming the pockmark geomorphology.
Optimization of spark plasma sintering parameters for NiTiCu shape memory alloys
Published in Materials and Manufacturing Processes, 2019
C. Velmurugan, V. Senthilkumar
Generally, NiTi alloys are fabricated in two methods such as liquid and solid state.[5,6] Among different solid state processes, powder metallurgy synthesis processes is beneficial due to low cost and simple procedure.[7] The high temperature material such as NiTi can be successfully manufactured by powder metallurgy methods such as selective laser melting (SLM),[8] conventional sintering (CS),[9] microwave sintering,[10] self-propagating high-temperature synthesis (SHS),[11] and metal injection molding (MIM).[12] Mechanical alloying process is used to synthesize the nanostructured NiTi-SMA with amorphous structured solid state solution. Sintering is a secondary process followed by the compaction which can increase the density of consolidated powders. The combined process of compaction and sintering is needed due to the growing of tremendous application in the field of powder metallurgy. A rapid densification process such as SPS has been used as a sintering technique for metals, alloys, composites and ceramics.[13]