An Elementary Course of Civil Engineering: For the Use of Cadets of the United States' Military Academy |
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abutments action angle appearance applied arch arising arranged axis bars base beams bearing blocks bolts bottom braces brick bridge built cables cast iron cause centre character combination connected consists construction courses covered cross section curved depend depth diagonal dimensions direction effect embankment engineer equal experiments extremities face feet force foundations frame give given greater hard heads heavy horizontal hydraulic inches inclined iron joints laid latter length less lime lower manner masonry mass material means method mortar natural obtained ordinary pieces piers piles placed plates portion position present pressure receive resistance rest ribs roadway sand secured segment side slope soil solid span square stone strain strength string structure struts subjected sufficient suitable surface suspended taken termed thickness timber tion upper uprights usually vertical wall weight width yield
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Page 286 - Where slips occur from the action of springs, it frequently becomes a very difficult task to secure the side slopes. If the sources can be easily reached by excavating into the side slopes, drains formed of layers of fascines, or brush-wood, may be placed to give an outlet to the water, and prevent its action upon the side slopes. The fascines may be covered on top with good sods laid with the grass side beneath, and the excavation made to place the drain be filled in with good earth well rammed.
Page 84 - ... determine the effect of a load lying constantly on a pillar, Mr. Fairbairn had, at the writer's suggestion, four pillars cast, all of the same length and diameter. The first was loaded with 4 cwt., the second with 7 cwt., the third with 10 cwt., and the fourth with 13 cwt. ; this last load was...
Page 281 - From this it appears that the angle of repose in the first case is represented by T|JO-, or T'T nearly; and that the slope of the road should therefore not be greater than one perpendicular to sixty-eight in length ; or that the height to be overcome must not be greater than one sixty-eighth of the distance between the two points measured along the road, in order that the force of friction may counteract that of gravity in the direction of the road. A similar calculation will show that the angle...
Page 86 - ... or less, produced in some cases a considerable set or defect of elasticity ; and judging from its slow increase afterwards, I was persuaded that it had not come on by a sudden change, but had existed, though in a less degree, from a very early period.
Page 284 - Pure sand and gravel may require a greater slope, according to circumstances. In all cases where the depth of the excavation is great, the base of the slope should be increased. It is not usual to use any artificial means to protect the surface of the side slopes from the action of the weather ; but it is a precaution which, in the end, will save much labor and expense in keeping the roadway in good order. The simplest means which can be used for this purpose, consist in covering the slopes with...
Page 299 - The repairs should be daily made by adding fresh material upon all points where hollows or ruts commence to form. It is recommended by some that when fresh material is added, the surface on which it is spread should be broken with a pick to the depth of half an inch to an inch, and the fresh material be well settled by ramming, a small quantity of clean sand being added to make the stone pack better. When not daily repaired by persons whose sole business it is to keep the road in good order, general...
Page 288 - When the axis of the roadway is laid out on the side slope of a hill, and the road-surface is formed partly by excavating and partly by embanking out, the usual and most simple method is to extend out the embankment gradually along the whole line of excavation. This method is insecure, and no pains therefore should be spared to give the embankment a good footing on the natural surface upon which it rests, particularly at the foot of the slope. For this purpose the natural surface should be cut into...
Page 296 - A layer of broken stone, four inches thick, is laid over this pavement, for a width of nine feet on each side of the centre ; no fragment of this layer should measure over two and a half inches in any direction. A layer of broken stone of smaller dimensions, or of clean coarse gravel, is spread over the wings to the same iepth as the centre layer.
Page 83 - A long, uniform, cast-iron pillar, with its ends firmly fixed, whether by means of discs or otherwise, has the same power to resist breaking as a pillar of the same diameter, and half the length, with the ends rounded or turned so that the force would pass through the axis.
Page 275 - The stability of this part of the structure is fully insured, as the resistance of the anchorage is twice as great as the greatest strain to which the chains can ever be subjected. " The plan of anchorage adopted on the aqueduct varies materially from those methods usually applied to suspension bridges, where an open channel is formed under ground for the passage of the chains.