Earthwork forms the foundation of any structure and must be accurately estimated.
Complete Example: Building Earthwork
Building 20m × 15m, Plinth 0.75m above GL, Foundation 1.5m deep
Step 1: Excavation Volume
Pit size = (20+2×1) × (15+2×1) × 1.5 = 22 × 17 × 1.5 = 561 m³
Step 2: Backfill Required
Foundation = 2(20+15) × 1 × 1.5 = 105 m³
Plinth fill = 20 × 15 × 0.75 = 225 m³
Total = 330 m³
Step 3: Surplus/Deficit
Surplus = 561 – 330 = 231 m³ to cart away
Cost Calculation
| Item | Qty | Rate | Cost |
|---|---|---|---|
| Excavation | 561 m³ | ₹200 | ₹1,12,200 |
| Backfill (compacted) | 330 m³ | ₹150 | ₹49,500 |
| Cart away (with 25% bulking) | 288 m³ | ₹100 | ₹28,800 |
| TOTAL EARTHWORK | ₹1,90,500 | ||
Bulking & Shrinkage Factors
| Soil Type | Bulking % | Shrinkage % |
|---|---|---|
| Sandy soil | 10-15% | 5-10% |
| Clay soil | 20-30% | 10-15% |
| Rock | 30-40% | 15-20% |
