load stockpiled material into overheadhoppers and trucks.The production of any pit materialthat requires crushing and screeningdepends on the capacity of the processingequipment used.QUARRY OPERATIONSQuarrying involves not onlyextraction of material (rock) but alsocrushing and screening that makes therock suitable for use as constructionmaterial.Quarry TerminologyFigure 5-10 shows the names ofvarious quarry features.Overburdenisthe waste material that often overliespit or quarry sites. Deposits withinthe waste materials are called spoil andmust be removed before excavation ofthe construction materials lyingbelow. Overburden refers to loosematerial but locally it may includesolid rock lying above the desiredmaterial.Burden is the constructionmaterial on the face of a quarry. Thefloorof the quarry is the inside bottomsurface that marks the lower limit ofexcavation. Often quarries contain oneor moreworking floors at various levelsabove the final quarry floor. A quarrywall is a more or less vertical surfacethat marks the lateral limit ofexcavation. The face of a quarry is arock surface (usually vertical) fromwhich rock is to be excavated. The topof the face is called thecrest, and thebottom is called thetoe. A bench is asteplike mass of rock behind a faceand below a working floor, Notice thateach bench has a face, toe, and crest.Quarry DevelopmentThe layout of a quarry shouldprovide a gravity flow of material fromthe face to the crusher, from the crusherto the storage bin, and from the bin tothe hauling equipment, as illustrated infigure 5-11. A quarry laid out in thismanner assures that a maximum quantity ofrock can be processed with a minimum oflabor and equipment. In quarries laid outon the gravity-flow principle, thedrainageproblem is practicallyeliminated.Military quarries are generally ofthe open-face type with the verticalsurface of the rock exposed. DependingFigure 5-12.-Determining the direction of thequarry face.upon local conditions, they may be developedby the single- or multiple-bench method.Where the rock face is not exposed,core samples should be taken in a gridpattern so rock formations can be plotted,and the lay of the strata, the quality andquantity of the deposit, and depth ofoverburden can be determined. Should arock formation be jointed or stratified,the layout of the quarry is determined bythe strike (direction) of the formation;that is, the face of the quarry must bedirected at right angles to the strike(fig. 5-12). This ensures a vertical ornear vertical face with less chance ofundercutting the face and creating adangerous overhang.5-13
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