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Short note: Basement and retaining wall

Short answer

A basement is a storey below ground level requiring RCC retaining walls (200-300 mm) with waterproofing, drainage, ventilation, and fire exits. A retaining wall holds back earth, designed against overturning, sliding, and bearing failure under active earth pressure Pa = 0.5 KaγH² acting at H/3, with weep holes for drainage.

Write a short note on basement and retaining wall.

Basement

A basement is the storey of a building that is wholly or partly below ground level, used for parking, storage, services or shops. Its walls must resist earth pressure and ground water, so they are built as retaining walls (RCC, 200-300 mm thick) with a waterproofing (tanking) layer. Requirements: damp-proof floor and walls, drainage around the walls, adequate ventilation, lighting and fire exits, and a proper ramp or stair.

Waterproofing methods: integral waterproofing compound, bituminous membrane, cement plaster with a waterproofer, and drainage (French drain, sump pump).

Retaining wall

A retaining wall holds back earth where the ground level changes suddenly. Its types are gravity, cantilever, counterfort and buttress walls. It must be designed against overturning, sliding and bearing failure under the active earth pressure Pa=12KaγH2P_a = \tfrac12 K_a\gamma H^2, acting at H/3H/3 from the base. Weep holes and filters behind the wall prevent the build-up of water pressure.

  ground level
 ------------+    +
   backfill  |    |
   (soil)    |wall|    basement
    P_a ---> |    |    (inside)
             |    |
 ____________|    |_____________
          ===========  footing

✓ Answer checked by Claude Opus 5.5 (high effort)

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