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EARTHWORK   VOLUME - 14070_208
Table  10-2.Table  of  Cumulative  Yardage - 14070_210

Engineering Aid 1 - Advanced Structural engineering guide book
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economical  haul  distance  is  the  mass   diagram method. A mass diagram is a graph or curve on which the algebraic sums of cuts and fills are plotted against linear   distance.   Before   these   cuts   and   fills   are tabulated,  the  swells  and  compaction  factors  are considered  in  computing  the  yardage.  Earthwork  that is in place will yield more yardage when excavated and  less  yardage  when  being  compacted.  An  example of this is sand: 100 cubic yards in place yields 111 cubic  yards  loose  and  only  95  cubic  yards  when compacted.  Table  10-1  lists  conversion  factors  for various types of soils. These factors should be used when you are preparing a table of cumulative yardage for a mass diagram. Cuts are indicated by a rise in the curve and are considered positive; fills are indicated by a drop in the curve and are considered negative. The  yardage  between  any  pair  of  stations  can  be determined  by  inspection.  This  feature  makes  the  mass diagram a great help in the attempt to balance cuts and fills within the limits of economic haul. The limit of economic haul is reached when the cost of haul and the cost of excavation become equal. Beyond that point it is cheaper to waste the cut from one place and to fill the adjacent hollow with material taken from a nearby borrow pit. The limit of economic haul will, of course, vary at different stations on the project, depending on the nature of the terrain, the availability   of   equipment,   the   type   of   material, accessibility,  availability  of  manpower,  and  other considerations. The term free-haul distance  means a distance over which hauling material involves no extra cost. This distance  is  usually  taken  to  be  about  500  feet– meaning that it is only for hauls longer than 500 feet that the limits of economic haul need to be considered. Table 10-1.—Soil Conversion Factors (Conversion Factors for Earth-Volume Change) 10-11







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