Subsurface characteristics

The Earth s crust constitutes the subsurface and is the domain of most engineering practices. The crust is formed from materials called rocks often covered with a veneer of unconsolidated material. This consequently results in two subsurface types. 

The part of the crust constituted from consolidated rocks is referred to as the bedrock. These rocks are also referred to as intact rocks. The physical properties of fresh (unweathered) rock depend on their constituent minerals and texture and the presence of structural discontinuities like fractures, joints and bedding. 

There are two types of intact rocks designated by the terms rock mass and rock material. The rock material refers to intact rocks that contain no joints. Rock mass refers to the bedrock that consists of intact rock with joints. 

Each of these main rock types are tremendously varied and classified on the basis of composition and structure in addition to the mode of origin. Based on their mode of origin, rocks are broadly classified as igneous, sedimentary and metamorphic rocks. 

Igneous rocks form by the cooling and crystallization of hot, molten magma or lava from within the Earth solidifying at or near the surface. There are a wide variety of igneous rocks and they may be classified according to a number of criteria. Those formed at depth are termed intrusive or plutonic and those formed on the surface are called extrusive or volcanic rocks as shown in Table 2.5. 

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The effectiveness of the different primary migration mechanisms is determined by the subsurface characteristics of both the hydrocarbons to be moved and the medium through which the movement takes place. 

Surface and subsurface characteristics Surface and subsurface properties... 

Systematic Setting of Surface and Subsurface Characteristics by Machining... 

Component performance is influenced decisively by surface and subsurface characteristics. They may either extend or shorten the lifetime of a component considerably. Many of the characteristics are defined by the final machining process, so that it is of particular importance for component quality. 

Site and subsurface characteristics directly affect the choice of foundation type, capacity of the foundation, foundation construction methods, and bridge cost. Subsurface and foundation conditions also frequently directly or indirectly affect the route alignment, bridge type selection, and/or foundation span lengths. Therefore, an appropriately scoped and executed foundation investigation and site characterization should include the following ... 

Groundwater monitoring is a necessary component in any investigation of subsurface contamination. A wide variety of information can be gleaned from the data including groundwater velocity and direction, and contaminant identification and concentration. These data can be combined with other observations to infer various characteristics of the contamination. Examples are source and timing of the release, and future location of the contaminant plume. 

Etch Mechanisms. Most wet etches for the compound semiconductors employ oxidation of the semiconductor followed by dissolution of the oxide. For this reason, many wet etches contain the oxidant hydrogen peroxide, although nitric acid can also be used. One advantage of wet etching over dry is the absence of subsurface damage that is common with dry etching. Metal contacts placed on wet-etched surfaces exhibit more ideal characteristics than dry-etched surfaces. 

Zhu, D. and Hu, Y. Z., A Computer Program Package for the Prediction of EHL and Mixed Lubrication Characteristics, Friction, Subsurface Stresses and Flash Temperatures Based on Measured 3-D Surface Roughness," Tribol. Trans., Vol. 44, No. 3,2001, pp. 383-390. 

Figure 8.5 shows the LEIS spectra of ZnAl204 and ZnO as a characteristic example of a multicomponent system analyzed by this technique [Brongersma and Jacobs, 1994]. Since only the surface peaks of A1 and O were detected for ZnAl204, the Zn atoms must be located in the subsurface layers. The onset of the tail agrees between the spectra, indicating that Zn is present in the second and deeper layers. This example illustrates the strength of the LEIS technique, in that characteristic peaks from different elements can be used to selectively analyze the atomic composition of the topmost surface. In addition, the shape of the tails could provide information on the in-depth distribution of the elements. 

Components of the pumping system reflect both practical aspects related to the characteristics of the site facilities and the subsurface hydrogeologic conditions encountered. The pumps selected are pneumatic, double-diaphragm suction-lift pumps. The advantages of these pumps include ... 

Each recovery site has its own individual site-specific characteristics. Subsurface stratigraphy and other geologic considerations, depth to water table, hydraulic conductivity, aquifer(s) thickness, size of product pool, physical characteristics of the... 

Double-diaphragm suction-lift pumps also have advantages relative to varying subsurface hydrogeologic characteristics encountered at different sites. These include ... 

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