- 2079 Bhadra · 2 marks
Accessible and inaccessible exploration methods
Short answer
Accessible methods like test pits permit direct observation and undisturbed block sampling but are limited to shallow depths (~3–6 m). Inaccessible methods such as borings can reach any depth but strata are inferred from samples and cuttings.
Differentiate between accessible and inaccessible methods of exploration.
| Point | Accessible methods | Inaccessible methods |
|---|---|---|
| Meaning | Soil can be examined directly by a person entering the excavation | Soil is examined only by samples brought up from a hole |
| Examples | Test pits, trenches, shafts, drifts | Auger boring, wash boring, percussion, rotary drilling |
| Depth | Shallow (up to about 3-6 m) | Any depth |
| Observation | In-situ strata, structure, fissures visible; undisturbed block samples possible | Strata inferred from samples/cuttings |
| Cost | Costly for depth, dewatering needed | Cheaper per metre of depth |
| Use | Small, important sites; check of weak zones | Routine investigation of buildings and bridges |
✓ Answer checked by Claude Sonnet 5.5
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