ESTIMATING EARTHWORK DR Nabil Dmaidi Estimating Earthwork includes

ESTIMATING EARTHWORK DR. Nabil Dmaidi

Estimating Earthwork includes: n 1. Excavation n 2. Grading: Moving earth to change elevation n 3. Temporary shoring n 4. Back fill or fill: Adding earth to raise grade n 5. Compaction: Increasing density n 6. Disposal DR. Nabil Dmaidi

Productivity Factors A. Job conditions – – – Material type Water level and moisture content Job size Length of haul Haul road condition (accessibility and load restrictions) DR. Nabil Dmaidi

Productivity Factors (cont. ) B. Management conditions – – – Equipment conditions and maintenance practices Skills of work force and management Planning, supervision and coordination of work. DR. Nabil Dmaidi

Job Efficiency Factors for Earthmoving Operations DR. Nabil Dmaidi

Units of Measure n Cubic Yard (bank, loose, or compacted) DR. Nabil Dmaidi

1. 0 CUBIC YARD IN NATURAL CONDITION (IN-PLACE YARD( 1. 25 CUBIC YARD AFTER DIGGING (LOOSE YARDS( 0. 90 CUBIC YARD AFTER COMPACTED (COMPACTED YARDS( 1. 25 1. 0 In place 0. 90 Loose DR. Nabil Dmaidi Compacted

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 DR. Nabil Dmaidi

Swell: A soil increase in volume when it is excavated. Swell (%) = ( Bank density Loose density Load factor = Loose density Bank density - 1) x 100 Bank Volume = Loose volume x Load factor DR. Nabil Dmaidi

Shrinkage: A soil decreases in volume when it is compacted Shrinkage (%) = (1 ) x 100 Bank density Compacted density Shrinkage factor = 1 - Shrinkage Compacted volume = Bank volume x Shrinkage factor DR. Nabil Dmaidi

Approximate Material Characteristics n Exact values will vary with grain size, moisture content, compaction, etc. Test to determine exact values for specific soils. DR. Nabil Dmaidi

Typical Soil Volume Conversion Factors DR. Nabil Dmaidi

Estimating Earth work for Trenches and Foundations ” 0 -’ 2 or more DR. Nabil Dmaidi Angle of Repose

Approximate Angle of Repose DR. Nabil Dmaidi ge S ed 1: 1 Slo (4 pe f 5 D o eg r Av. ) era en d m m Re co act e 1/2 d An : 1 ( gula 63 r De Grav g. ) els mp Co Original Ground Line Solid Rock, Slate or Cemented Sand Gravel (90 Deg. ) oi ls For Sloping Sides of Excavation d an d S San rp. ) e a s h g Loo ) d S 3 De d e. e t nd Deg ac : 1 (3 u p o 6 m 2 ll R : 1 (2 Co 1 1/ 2 We

Calculating Earthwork Quantities. 1 End Area Method. 2 Contour Line/ Grid Method DR. Nabil Dmaidi

1. End Area Method n Used in sites where length is much greater than width DR. Nabil Dmaidi

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. DR. Nabil Dmaidi

Project Site Showing 100 Stations C’ B’ E’ D’ F’ 88 86 84 84 '300 80 82 82 80 78 A’ '100 88 C B A 86 Fill t Cu '100 E D '100 '500 DR. Nabil Dmaidi '100 F '100

80 Sec. A’- A 78. 5 78 76 82 Project Cross Sections Sec. B’- B 80. 3 80 78 84 Sec. C’- C 82. 3 82 80 86 Sec. D’- D 84. 2 84 88 Sec. E’- E 86. 2 86 90 Sec. F’- F 88. 2 88 DR. Nabil Dmaidi

Cross-Section @ A’- A 80 Area = 107 x 1. 0 2 = 53. 5 79 78. 5 78 76. 7 Area = 193 x 1. 8 2 77 = 173. 7 76 Section A’- A DR. Nabil Dmaidi

Cross-Section @ B’- B 82 Area = 90 x 1. 5 2 = 67. 5 81 80. 3 80 76. 7 Area = 210 x 1. 8 2 79 = 189. 0 78 Section B’- B DR. Nabil Dmaidi 81. 8

Table 1. Cumulative Earthwork Quantities DR. Nabil Dmaidi

2. Contour Line/ Grid Method Used for parking lots and site “leveling” n Grid size from 10’x 10’ to 50’x 50’ n the greater the terrain variance the smaller the grid n DR. Nabil Dmaidi

. 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) 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. DR. Nabil Dmaidi

A C B E D F G ’ 300 ’ 88 ’ 89 ’ 90 ’ 91 ’ 92 ’ 93 ’ 94 87. 6 88. 5 89. 3 90. 3 91. 5 A B C D E 87. 6 88. 6 89. 4 90. 4 91. 6 93. 2 G H J K L M 87. 4 88. 2 89. 5 90. 6 91. 6 92. 7 N O P Q R S 87. 2 87. 7 89. 0 90. 4 91. 3 92. 0 No Scale 95. 0 F Notes: 1. Bring the entire site to elevation 90. 2. All grids are 50’x 50’ = 2500 sq. ft. 3. Present contours DR. Nabil Dmaidi 94. 3 93. 5 93. 1

n Purpose Grade the entire site to grade 90’ Need Fill n Quick and Dirty Assume one grid Existing 90. 50 Proposed 90. 00 Cut 0. 50 Need Cut '300 '91 '90. 5 Total Cost = = 833 CY 150 x 300 x 0. 50 27 DR. Nabil Dmaidi '150 '90

If we choose the grid size to be 50’x 50’ 88. 6 Average elevation 87. 6+88. 5+87. 6+88. 6 = 4 = 88. 08 change= 90 -88. 08 = 1. 92 cut = = 177. 77 CY and so on. 87. 6 DR. Nabil Dmaidi 87. 6