Quiz on Forces Affecting Soils

What creates the downward or vertical stress in soil?

• The weight of the soil

• Machinery vibration

• Water content

• The surrounding soil

What provides horizontal support to the soil?

• Frost action

• Water pressure

• The surrounding soil

• The weight of the soil

When is the soil considered stable?

• When water content is high

• When stresses are equal

• When horizontal stress is greater

• When vertical stress is greater

What happens when a cut is made in the soil?

• Water content decreases

• Soil becomes stronger

• Stresses become unequal

• Stresses become equal

Which of the following is NOT a cause of soil instability?

• Shock and vibration

• Stable soil structure

• Saturation of soil

• Increase in depth of the cut

What is the effect of water pressure in ground cracks near excavation walls?

• Decreases soil stability

• Increases soil stability

• Has no effect

• Strengthens soil

What is the impact of machinery and traffic on soil?

• Reduces water content

• Increases soil strength

• Stabilizes soil

• Causes shock and vibration

What is the role of frost action in soil stability?

• Increases soil stability

• Improves soil structure

• Decreases soil stability

• Has no effect

Where does the fracture point usually occur during a collapse?

• Back from the face, equal to half to three quarters of the depth

• At the face of the excavation

• Above the excavation

• Below the excavation

What is the key to maintaining stable soil faces?

• Increasing water content

• Reducing soil weight

• Ensuring stresses are weaker than soil strength

• Ensuring stresses are stronger than soil strength