Earthworks

Earthworks, in Engineering, is a term applied to cuttings or to embankments; to the removal of earth as in the cases of canals, trenches, docks, or railway cuttings, or to the systematic deposition of the same, as in the cases of earth-dams, elevated canals, or railway embankments. The general methods of executing earthwork are similar in most applications of the work. In the formation of a railway over irregular ground, the elevation is usually chosen so that the amount of cutting shall be approximately equal to the amount of embankment, the earth obtained from the former being conveniently discharged where required for the latter. The work is proceeded with continuously, the full height of the railway at any one place being reached before the further excavation or embankment is begun. This renders the laying-down of rails convenient, and the material can therefore be easily shifted in waggons, etc. Steam excavators are much used, and their transit from place to place requires the rails. The angle of slope of a cutting for embankment depends upon the nature of the ground. Chalk may be at a very steep angle or batter, but a moist, loose, gravel soil requires an easy slope, the angle of repose (q.v.) of that material being so small. Continual vibration, such as that produced by passing railway trains, may in course of time affect their stability, as also may inefficient drainage, or alternation of extremes of temperature. The amount of earthwork of any such undertaking requires careful calculation, but in the case of those with the ordinary trapezoidal section the estimation is easy. The sectional area is then obtained by multiplying the depth of the section by the average of the top and bottom widths; the cubic contents of any length of such an earthwork is the product of that length and the sectional area.