Excavator

“ Huts at temple.
Demands of the work.
In the externals of the work an excavator should be always his own best workman. If he be the strongest on the place, so much the better; but at all events he should be the most able in all matters of skill and ability. Where anything is found it should be the hands of the master that clear it from the soil; the pick and the knife should be in his hands every day, and his readiness should be shown by the shortness of his7 finger-nails and the toughness of his skin. ”

“ Organization, both of the plan of work, and of the labourers, is very necessary. Scheming how to extract all that is possible from a given site, how to make use of all the conditions, how to avoid difficulties; and training labourers, keeping them all firmly in hand, making them all friends without allowing familiarity, getting their full confidence and their goodwill;—these requirements certainly rank high in an excavator’s outfit. ”

“ After a week of work in the soil, feeling for delicate things in a way that no tools can do, the skin almost wears through, and the nails break down. But a week or two more at it, and the excavator grows his gloves, and is in a fit state for business, with the skin well thickened, and ready to finger through tons of grit and sand. ”

“ Taking the north fosse at the dimensions already given, its excavation would involve the removal of 5,585,072 cubic yards. A modern excavator, stimulated by pay proportioned to his work, enjoying food, and raiment, and shelter, such as the ancient Briton was a stranger to, and possessing the advantage of good tools, and good organization, can remove the enormous quantity of twenty cubic yards of earth per day. ”

“ And whatever is not businesslike in archaeology is a waste of the scanty material which should be left for those who know how to use it. An excavator must make up his mind to do his work thoroughly and truly, or else to leave it alone for others who will take the trouble which it deserves and requires. ”

“ The French have lately employed in connection with their excavators a mechanism similar to the élévateur, already described. It is called the transporteur, and consists of an elevated structure which performs the same service for an excavator that the élévateur does for a dredge. The earth is deposited from the buckets upon an endless belt. This passes round two drums about two hundred feet apart, and in the interval rests upon friction-rollers. The earth is thus carried outward from the excavation, and at the same time upward. ”

“ As the steam navvy or excavator has now become necessary plant upon most large public works, and greatly accelerates the speed at which cuttings can be executed, always provided the excavation is not of a treacherous nature, and is in such quantity that if not so used it would have to be run to spoil, many narrow valleys in the near future will probably be wholly or nearly closed with an earthen embankment, thereby effecting an important saving of time and expense ”

“ In the comparison the hand crew is assumed to dig 315 linear feet of trench 28 inches wide by 12 feet deep in a day of 10 hours. This assumes that each man will excavate 7 cubic yards per day. The machine is assumed to excavate 250 feet of the same trench. The comparison indicates that an excavator will work at about 50 per cent of the cost of hand excavation, if the cost of moving the machine is not included. ”

“ Their progress is slow at first, but after they have made room to stand on the excavation, they proceed rapidly, still working with their bills, and carefully pushing out the loosened sand with their feet. At one time the male, at another the female, is the excavator. ”

“ The excavation is effected in different ways. We are very eclectic at Panama. We reject no system, no method, and as the earth varies at every step, as the works at one point do not resemble those at another, we can try different ways. At certain places we have mellow earth, which is generally composed, in the valleys, of clay mixed with a feldspathic sand. In such places we can make the attack by mechanical processes. We employ excavators. There are two sorts of excavators, the French and American. The American excavators are very ingenious, and in mellow soil they give satisfactory results. ”

“ In excavating, dredging and draining, the inventions of the century have been very numerous, but, like numerous advances in the arts, such inventions, so far as great works are concerned, have developed from and are closely related to steam engineering. [Pg 106]
The making of roads, railroads, canals and tunnels has called forth thousands of ingenious mechanisms for their accomplishment. A half dozen men with a steam-power excavator or dredger can in one day perform a greater extent of work than could a thousand men and a thousand horses in a single day a few generations ago. ”

“ The timbering of the sides and roof through this description of working is very tedious, and attended also with a considerable amount of risk. The absence of really solid ground on which to place or shore up the supports, taxes the skill of the excavators, and very often, when a short length has been made apparently secure, it will come down with a run, compelling all hands to beat a hasty retreat. The permanent lining through such treacherous material should follow the excavation very closely, and special care should be exercised in building the walls, arching and invert. ”

“ Wheel excavators are not adapted to the excavation of sewer trenches over 3 to 4 feet in width and 6 to 8 feet in depth. The endless-chain excavators are suitable for depths of 25 feet with widths from 22 to 72 inches, and due to the arrangement permitting buckets to be moved sideways they will cut trenches of different widths with the same size buckets. ”

“ They are even used for excavating the cellars of large city buildings. The machine must be supported on road wheels or on skids. When used for excavating sewer trenches, it is sometimes mounted on a platform spanning the trench. However, the steam shovel is rather limited in its reach. The largest ordinary steam shovels have a clear lift of but sixteen feet and can make a cut only sixty feet wide at the top.
For more extensive excavating as well as for digging ditches and trenches the drag-line excavator has recently come in to use. In these machines a scraper takes the place of the dipper. ”

“ In the excavation through stratified rocks it is necessary to note carefully the lie of the strata, whether horizontal, vertical, or shelving, as with each one the excavators are exposed to risks, against which every precaution should be taken. A large horizontal slab of solid-looking rock will suddenly break and fall down without any warning. ”

“ Excavation. —Fig. 68 is the excavation diagram of the Belgian method of tunneling. The excavation is begun by opening the center top heading No. 1, which is carried ahead a greater or less distance, depending upon the nature of the soil, and is immediately strutted. This heading is then deepened by excavating part No. 2, to a depth corresponding to the springing lines of the roof arch. The next step is to remove the two side sections No. 3, by attacking them at the two fronts and at the sides with four gangs of excavators. ”

“ Foundations are usually executed by excavators or navvies, and the tools and implements used are boning rods, level pegs, lines, spirit level, pickaxe, various shovels, wheel-barrow, rammer or punner, &c. In digging the ordinary trenches and excavations, should the ground be loose, planking and strutting have to be employed. ”

“ The air was at times biting cold, but invigorating, and every man, including the boss and the cook and even the night herder, fell to the work with a will that finally meant victory. In places we operated in the drifts as you see the excavators in a city cellar or subway operate, digging down to the surface and then benching as the open-ground miners or cellar excavators do, the men below tossing the blocks of snow up to the bench above and they in turn passing it to the top of the drift. ”

“ We may therefore ascribe most of the evils and damages to the increased range of action, and still more to the rude implements the men have used, whenever they met with any difficulty in moving the frames. If it is considered that we had no other men to train in the use of this immense machine but excavators and miners, very great allowance must be made for what has occurred. ”

“ Riggers were preparing the gear for it, sawyers cutting wood for various purposes, rope-makers making lashing and seizing stuff from the pieces of cable crept [2] up from the bottom, and two sets of blacksmiths at their forges; those of the Warspite making hoops, bolts, and nails, from various articles which had been crept up; and those of the Lightning reducing the large diving bell and constructing a smaller one; five gangs of excavators leveling platforms on the heights above the cove, cutting roads to lead to them, and fixing bolts in numerous parts of the faces of the cliffs ”

“ About 7 or 8 feet above the cutting edge a strongly framed iron floor is riveted to the vertical sides, and strengthened by plate-iron under-brackets placed at short distances. The excavators work in the space below the floor, and the excavated material is passed up through openings formed in the floor at convenient points to suit the working. The methods of lowering a caisson are the same as for lowering a cylinder. ”

“ But even excavators, or perhaps it is more correct to say some of them, have their failings. They are apt to look down from an immense height upon an amateur digger as something too ignorant for words ”

“ I asked him why the excavators, instead of working among these second-class graves, were not set to search for the tombs of the kings of the eighteenth dynasty, supposed to be waiting discovery in a certain valley called the Valley of the West. He shook his head. The way to the Valley of the West, he said, was long and difficult. Men working there must encamp upon the spot; and merely to supply them with water would be no easy matter. He was allowed, in fact, only a sum sufficient for the wages of fifty excavators ”

“ The excavating gangs are divided up into units of 20 to 50 men under one foreman or straw boss, and among the men may be a few higher priced laborers who set the pace for the others. Each laborer on excavation should be provided with a shovel, the style being dependent on the character of the material being excavated and the depth of the trench. In stiff material and deep trenches requiring the lifting of the material in the shovel, long-handled pointed shovels should be used. In loose sandy material loaded directly into buckets short-handled, square pointed shovels are satisfactory. ”

“ The shoring and strutting of the excavation is to be done in such manner, with poling boards, waling pieces and struts, as the surveyor shall consider necessary.
All surplus earth or material is to be carted away as speedily as possible. Care must be taken where the excavation is made in a road or path to keep separate the surface material from the lower, so as to replace them in their proper positions.
The excavation shall in all cases where practicable be in open cutting, and not by shafts and headings. ”

“ Excavating the Culebra Cut, Panama Canal
Excavation, the process of removing soil or rock in engineering or exploration works, such as for docks, retaining-walls, railway cuttings, canals, foundations, &c. On a small scale, or in situations unsuitable for machinery, it is performed by hand, the soil being first loosened by the pick, and then shovelled into barrows. In rocky soils, drilling and explosives may be employed. In large works power shovels or 'steam-navvies' are employed, which are essentially cranes carrying a large shovel, or a system of steel buckets of the dredger type. ”

“ In very large works of excavation in soft soil a steam digger is used for the bulk of the work. It consists of a large steel bucket with a cutting edge; this is lowered by means of a crane into the excavation, and on being withdrawn cuts off a portion of soil which is hoisted and deposited in carts for removal to any desired position within the radius commanded by the crane. The work of trimming the excavation to a regular shape must always be done by manual labour.
Concrete for filling into the foundations is usually mixed by navvies; for large works it is sometimes mixed by machinery. ”

“ Continuous bucket machines, drag lines, and occasionally steam shovels are not adapted to conditions where rocks, pipes and other underground obstacles are frequently met.
The following problem is an example of the work necessary in making a comparison of the relative economy of machine and hand excavation:
It is assumed that a man can excavate 15 feet of trench 30 inches wide and 8 feet deep in 10 hours. He receives 55 cents per hour for his work. A machine costing $10,000 has a life of 6 years. ”

“ Under the worst conditions of excavation in a hard cemented gravel it may be necessary to provide each man with a pick as well as a shovel, whereas in sand only a shovel is necessary. Two or three crowbars, axes, a length of chain, two or three screw jacks, etc., are provided per gang in case of an unexpected encounter with an obstruction in the trench, such as a boulder, a tree stump, a length of pipe, etc. ”

“ Iron shields, or protection chambers for the miners advancing the excavation, have been used with great success in carrying on work through loose wet strata which appeared to defy all other means of progress. Solid rock, chalk, or compact clay, may present no difficulty so far as they go, but a continued dip in the gradient, or a line of fault, may suddenly change the entire course of operations, and require the immediate use of the most powerful pumping machinery and protective appliances. ”