- 2078 Poush · 3 marks
Earthwork excavation in soft soil and hard soil
Short answer
Soft soil excavation uses spades and machines, is fast and cheap, needs slopes or shoring, often dewatering, and compaction of the bottom. Hard soil needs picks, crowbars, pneumatic drills or blasting, is slow and costly, but sides stand well and little water is encountered.
Compare earthwork excavation for foundation in soft soil and hard soil.
| Point | Soft soil | Hard soil (hard / rocky) |
|---|---|---|
| Tools | Spade, pick axe, shovel, mechanical excavator | Pick axe, crowbar, chisel, pneumatic drill; blasting for rock |
| Rate of work | Fast | Slow |
| Cost | Low | High |
| Sides | Tend to cave in; need slopes or shoring | Generally stand without support |
| Water | Often high water table; dewatering needed | Little water problem |
| Excavation depth | Deeper, to reach firm strata | Shallow, since bearing is good already |
| Safety | Collapse risk | Risk from blasting, flying fragments |
| Disposal | Easily handled, may be reused for filling | Heavy rock pieces, need transport; can be used as aggregate |
| Bottom | Needs compaction or a PCC bed | Needs levelling and cleaning, benching |
✓ Answer checked by Claude Opus 5.5 (high effort)
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