Kinds of Structures on the Geosphere

Numerous kinds of structures are located on or below the surface of the geosphere, most requiring some degree of excavation. The most common of these are as follows  

Railroads In general, the same considerations given to highway constrnction apply to railroads. Gradient is much more important with railroads and mnst be mnch lower for them 

Tnnnels An important consideration is whether a tunnel is constructed through solid rock or through poorly cohesive earth, thus requiring structures to prevent the flow of earth into the tunnel. It is common for both types of material to be encountered in the same tunnel. Rock structure and rock fractures must be considered. Also important is the potential for water infiltration and for means to remove water. 

Dams Both concrete and earth dams require careful assessment of the geological strata involved. A dam is almost always placed across a valley, which then fills upstream with water. The susceptibility of the reservoir slopes to landslides must be considered such slides may be more likely as the bottom parts of the slopes become constantly saturated with water from the reservoir. The rate of sediment accumulation in the reservoir should be evaluated. The strata upon which the dam rests are very important, and its strength, stability, and potential to develop routes for leakage of water must be evaluated. Especially in the case of earthen dams, the suitability of earthen material in the vicinity for construction is important. 

Mines There is not much choice of locations of mines because they must be placed exactly where the desired minerals are found. However, an evaluation of the geosphere at the location of a mine can be used to determine its construction. A major issue in designing a mine is the choice between an underground mine and an open pit. The type of mine construction depends strongly on the type and stability of the earthen material that must be excavated. Water infiltration from groundwater sources is a very important consideration and may require elaborate measures for pumping and drainage. Especially for coal mines, the potential for the infiltration of explosive methane must be known. Also important is the consideration of locations for the placement of mine spoils (wastes). 

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