What side slope should the walls of the test pit have to safely observe soils?

What side slope should the walls of the test pit have to safely observe soils?

• A. 1 vertical unit to 1 horizontal unit
• B. 2 vertical units to 1 horizontal unit
• C. 1 vertical unit to 2 horizontal units
• D. No slope is required

Answer: (A)

Excavation stability and visibility of the soil profile are the key ideas here. A side slope of one vertical unit to one horizontal unit (a 45-degree face) provides a safe balance: it’s steep enough to expose a good amount of the soil layers for observation, while still being stable enough to resist collapsing under typical, near-surface soil conditions. Vertical walls are risky because they can cave in, and a very shallow slope would waste space and still pose safety challenges or require a larger pit to observe effectively. In many field situations, this 45-degree slope is the practical choice for safely examining soils in a test pit.

Excavation stability and visibility of the soil profile are the key ideas here. A side slope of one vertical unit to one horizontal unit (a 45-degree face) provides a safe balance: it’s steep enough to expose a good amount of the soil layers for observation, while still being stable enough to resist collapsing under typical, near-surface soil conditions. Vertical walls are risky because they can cave in, and a very shallow slope would waste space and still pose safety challenges or require a larger pit to observe effectively. In many field situations, this 45-degree slope is the practical choice for safely examining soils in a test pit.