Subsoil structures

Since the spreading behaviour of organic substances in subsoil is very complicated depending on the site (subsoil structure) and material characteristics, at this point only a simplified description is given. For detailed information refer to the available technical literature [8,9]. 

The crop will grow in a wide range of soil and climatic conditions provided the land is well drained, pH over 6, and the soil and subsoil structure is good. 

Grass roots can grow and absorb water down to 1 m, or deeper if soil structure is good, although subsoil water is usually poorer in nutrients than topsoil water (Frame, 1992). Transpiration is highest... 

Although the above studies conducted with packed columns are important from a fundamental standpoint as they relate to the mechanisms of cell sorption to solid surfaces, in situ remediation of contaminants in subsoils requires microbial transport in well-structured soils. The presence of soil macropores that facilitate preferential water flow is well appreciated (Thomas Phillips, 1979). Sorption phenomena are less important when bacterial transport occurs through structured soils in which cells pass unimpeded through relatively large conduits (Smith et al., 1985). 

Other biogenous elements. Of the other macrobiogenous elements, probably only calcium can be considered to be limiting. It maintains the elasticity of cell surface, activates some plant and animal enzymes, it is an important structural element of skeleton and sometimes also of animals shells. In some waters, such as water from peat moors or water on an extremely calcium-poor subsoil, the calcium content is so low that it becomes deficient for the majority of aquatic species [21]. 

The purpose of foundations is to distribute the loading from structures and equipment so that perpetual settlement of the load-bearing soil will not cause excessive maintenance or impair the usefulness of the plant. The selection of a suitable type of foundation or soil loading support structure depends on the loads to be transferred to the foundation, on the material on which the foundation rests, and on the method of placing the foundation as dictated by the subsoil conditions. 

Podzol-like soils formed in deciduous forests, where there is less resistant surface organic debris, are much less extracted. Deciduous trees assimilate more soil bases from the subsoil than do coniferous trees, and since the leaves decay more readily there is a constant return of bases from the subsoil to the surface, thereby offsetting in part the downward movement in the drainage. These podzol-like soils may have no bleached layer and much less distinct horizons than the true podzols. They are less acid, more fertile than the typical well-developed podzol, and the organic matter is more mixed with the soil mass. Typical podzols have little or no granular structure, whereas the gray-brown soils often have a fairly well-developed crumb structure. 

As the result of a 5-year field, laboratory and statistical study, Wischmeier and Man-nering (1969) concluded that the properties that contributed significantly to soil-loss variance included percentage of sand, silt, clay, and organic matter pH, structure and bulk density of plow layer and subsoil steepness and concavity or convexity of slope pore space filled by air residual effects of sod crops aggregation parent material and various interactions of these variables. ... 

Piles are used to transmit structural loadings to the subsoil when the surface sediments cannot support the load. They may be single or in groups, and may be fully or partially embedded. Recent advancement in installation equipment has allowed diese members to be driven in any desired environment and up to 460 m of water depth. The versatility of pile foundations has made them adaptable to most types of conditions and requirements. A detailed discussion of classical methods employed on land has been presented by Kezdi (1975). Methods employed offshore have been discussed by McClelland et al. (1967,1969), McClelland (1974), McQelland and Cox (1976), Randolph (1983), and Randolph and ( urvenec (2011). Methods and techniques applicable to the marine environment will be discussed in the following sections. 

For pile embankment construction, usually driven piles are used. Lateral displacement and large deformation will occur in the subsoil especially if the soil is very sensitive. As this may cause problems of instability in nearby structures, precautions need to be taken. The technique of pile embankment has been successfully used in Malaysia especially for construction of high road embankments on soft soils such as alluvial and marine clays, and peat. 

Nature and structure of the subsoil (types of rock, course of fissure zones)... 

Transient foundation uplift or rocking involving separation from the subsoil of an end-bearing foundation pile group or the contact area of a foundation footing could be allowed under impact loading provided sufficient consideration is given to the structural stability of the substructure. 

The water motion on a revetment structure can also affect the subsoil, especially when this consists of sand. 

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