ESTIMATING EARTHWORK - Universiti Teknologi Malaysia

1 ESTIMATING . EARTHWORK . Prof Awad S. Hanna ESTIMATING EARTHWORK EARTHWORK includes: 1. Excavation 2. Grading: Moving earth to change elevation 3. Temporary shoring 4. Back fill or fill: Adding earth to raise grade 5. Compaction: Increasing density 6. Disposal Prof Awad S. Hanna Productivity Factors A. Job conditions Material type Water level and moisture content Job size Length of haul Haul road condition (accessibility and load restrictions). Prof Awad S. Hanna Productivity Factors (cont.). B. Management conditions Equipment conditions and maintenance practices Skills of work force and management Planning, supervision and coordination of work. Prof Awad S. Hanna Job Efficiency Factors for Earthmoving Operations Management Condit ions*.

2 Job Condit ions** Excellent Good Fair Poor Excellent Good Fair Poor Prof Awad S. Hanna Units of Measure Cubic Yard (bank, loose, or compacted). Bank (BCY): Mat erials in it s nat ural st at e before dist urbance (in-place, in-sit u). Loose (LCY): Mat erial t hat has been compact ed or dist urbed or loaded Compact ed (CCY): Mat erial aft er compact ion Prof Awad S. Hanna CUBIC CUBIC CUBIC. YARD IN YARD AFTER YARD AFTER. NATURAL DIGGING COMPACTED. CONDITION (LOOSE (COMPACTED. (IN-PLACE YARDS) YARDS). YARD). In place Loose Compacted Prof Awad S. Hanna Volume Bank: VB. Bank cubic yards (BCY). Density B Lb /BCY. Loose: Vl Loose cubic yards (LCY). Density L Lb/LCY. Compacted: Vc Compacted cubic yards (CCY). Density C LB/CCY.

3 Prof Awad S. Hanna Swell: A soil increase in volume when it is excavated. Bank density Swell (%) = (Loose density - 1) x 100. Loose density Load factor = Bank density Bank Volume = Loose volume x Load factor Prof Awad S. Hanna Shrinkage: A soil decreases in volume when it is compacted Bank density Shrinkage (%) = (1 - ). Compacted density x 100. Shrinkage factor = 1 - Shrinkage Compacted volume = Bank volume x Shrinkage factor Prof Awad S. Hanna Approximate Material Characteristics Loose Bank Swell Load Mat erial (lb/cy) (lb/cy) (%) Fact or Clay, dry 2,100 2,650 26 Clay, wet 2,700 3,575 32 Clay and gravel, dry 2,400 2,800 17 Clay and gravel, wet 2,600 3,100 17 Eart h, dry 2,215 2,850 29 Eart h, moist 2,410 3,080 28 Eart h, wet 2,750 3,380 23 Gravel, wet 2,780 3,140 13 Gravel, dry 3,090 3,620 17 Sand, dry 2,600 2,920 12 Sand, wet 3,100 3,520 13 Sand and gravel, dry 2,900 3,250 12 Sand and gravel, wet 3,400 3,750 10 Exact values will vary with grain size, moisture content, compaction, etc.

4 Test to determine exact values for specific soils. Prof Awad S. Hanna Typical Soil Volume Conversion Factors Init ial Convrt ed t o: Soil Type Soil Condit ion Bank Loose Compact ed Clay Bank Loose Compact ed Common eart h Bank Loose Compact ed Rock (blast ed) Bank Loose Compact ed Sand Bank Loose Compact ed Prof Awad S. Hanna ESTIMATING Earth work for Trenches and Foundation 2'-0 . or more Angle of Repose Prof Awad S. Hanna Approximate Angle of Repose For Sloping Sides of Excavation Solid Rock, Slate or Cemented Sand and Gravel Original Ground Line (90 Deg.). Prof Awad S. Hanna Calculating EARTHWORK Quantities Area Method Line/ Grid Method Prof Awad S. Hanna 1. End Area Method Used in sites where length is much greater than width Prof Awad S.

5 Hanna CALCULATING EARTHWORK QUANTITIES. 1. End Area Method a. Take cross-sections at regular intervals, typically, 100' intervals. b. Calculate the cross-section end areas c. The volume of EARTHWORK between sections is obtained by taking the average of the end areas at each station in square feet multiplied by the distance between sections in feet and dividing by 27 to obtain the volume in cubic yards. Prof Awad S. Hanna Project Site Showing 100 Stations A' B' C' D' E' F'. 80. 82. 84. 86. 88. 300'. A B C D E F. 100' 100' 100' 100' 100'. 500'. Prof Awad S. Hanna 80. Sec. A'- A 78. 76. 82. Sec. B'- B Project Cross Sections 80. 78. 84. Sec. C'- C 82. 80. 86. Sec. D'- D 84. 88. Sec. E'- E 86. 90. Sec. F'- F 88. Prof Awad S.

6 Hanna Cross-Section @ A- A. 80. 107 x Area = = 2. 79. 78. 77. 193 x Area = = 2. 76. Section A'- A. Prof Awad S. Hanna Cross-Section @ B- B. 82. 90 x Area = = 2. 81. 80. 79. 210 x Area = = 2. 78. Section B'- B. Prof Awad S. Hanna Table 1. Cumulative EARTHWORK Quantities Sect ion Emb (CCY) Exc. (BCY) Exc. x B/C Net Exc. Cum Exc (CCY) (CCY) (CCY). A-B 672 224 254 - 418 - 418. B-C 567 441 499 - 68 - 486. C-D 215 791 896 681 195. D-E 0 1031 1167 1167 1362. E-F 0 1222 1384 1384 2746. Prof Awad S. Hanna 2. Contour Line/ Grid Method Used for parking lots and site leveling . Grid size from 10'x10' to 50'x50'. the greater the terrain variance the smaller the grid Prof Awad S. Hanna 2. CONTOUR LINE/GRID CELL METHOD(cont.). Step l Determine by visual study of the site drawing if the net total will be an import (more fill required than cut) an export (less fill required than cut) or a blend (cut and fill about equal).

7 Step 2. Determine the pattern of calculation points or grid size. Step 3. Determine elevations at each calculation location, the corners of each grid. Step 4. Calculate the cubic yards of cut or fill required in each grid cell. Step 5. Add the individual Grid Cell quantities together to arrive at the total cut, total fill volume and the import or volume export yardage required for the job. Prof Awad S. Hanna A B C D E F G. 300'. 88' 89' 90' 91' 92' 93' 94'. A B C D E F. G H J K L M. N O P Q R S. Notes: 1. Bring the entire site to elevation No Scale 90. 2. All grids are 50'x 50' = 2500 sq. ft. 3. Present contours Prof Awad S. Hanna Purpose Grade the entire site to grade 90'. 90'. Need Need 150'. Fill Cut 300'. Quick and Dirty Assume one grid 90' 91'.

8 Existing '. Proposed Cut Total Cost =150 x 300 x = 833CY. 27. Prof Awad S. Hanna If we choose the grid size to be 50'x50'. Average elevation = + + + 4. = change = = cut =. = CY. and so on. Prof Awad S. Hanna