In soil mechanics, the number and disposition of bore holes are varied, depending upon the
- Asubsoil conditionCorrect
- Bearth surface
- Cunderground water
- Datmosphere
Solution
Concept
The number and position of bore holes depend mainly on how the subsoil changes from place to place.
Step-by-step solution
1. Bore holes are made to find the type and depth of the soil layers below the site. 2. If the subsoil is uniform, fewer bore holes at wider spacing are enough. 3. If the subsoil is erratic or varies a lot, more bore holes at closer spacing are needed. 4. So the number and layout of bore holes depend on the subsoil condition. Answer is (A).
Explanation
Soil exploration aims to know the soil layers below the structure. When the subsoil is uniform, only a few bore holes are needed. When the subsoil changes a lot, more bore holes are placed closer together.
Why the other options are wrong
B: The ground surface shape does not decide the bore hole plan. C: Ground water level is recorded during boring, but it does not decide the number of holes. D: The atmosphere has no role in the bore hole layout.
Shortcut
Bore holes study the subsoil, so the subsoil decides their number and spacing.
Common mistake
Choosing underground water, because the water table is also noted during boring.
Correct answer: A) subsoil condition