Active Earth Pressure

Definition

Active earth pressure is the lateral force exerted by soil on a retaining structure when the soil is allowed to expand, typically resulting from the soil's weight and any external loads. This concept is crucial for understanding how earth retaining structures behave under various conditions, ensuring stability and safety in construction.

5 Must Know Facts For Your Next Test

1. Active earth pressure occurs when a retaining wall moves away from the backfill, allowing the soil to expand and exert lateral pressure.
2. The calculation of active earth pressure can be derived using Rankine's theory, which simplifies the analysis under certain assumptions.
3. The angle of internal friction of the soil plays a significant role in determining the magnitude of active earth pressure.
4. Active earth pressure is generally lower than passive earth pressure because it reflects a state where the soil is in tension rather than compression.
5. Understanding active earth pressure is essential for designing safe retaining walls and other structures that interact with soil.

Review Questions

• How does the concept of active earth pressure relate to the stability of retaining walls during movement?
  • Active earth pressure is crucial for understanding how retaining walls behave when they are subjected to movement away from the backfill. When a wall moves, it allows the soil behind it to expand, which reduces the lateral force exerted by the soil. This reduction in force helps prevent failure of the structure by balancing internal and external pressures, maintaining stability during various loading conditions.
• Compare and contrast active earth pressure with passive earth pressure in terms of their applications in engineering design.
  • Active and passive earth pressures serve different roles in engineering design. Active earth pressure occurs when a retaining wall moves away from soil, allowing expansion and resulting in lower lateral forces. In contrast, passive earth pressure arises when a wall pushes against soil, leading to higher lateral forces due to compression. Engineers must account for both pressures in their designs to ensure that structures can withstand potential movements and remain stable under varying conditions.
• Evaluate how Rankine's Earth Pressure Theory applies to real-world scenarios involving active earth pressure and its implications for construction safety.
  • Rankine's Earth Pressure Theory provides essential equations for calculating active earth pressure based on simplified assumptions about soil behavior. In real-world scenarios, these calculations help engineers predict how retaining structures will respond to changes in load or movement. By understanding these dynamics, engineers can design safer constructions that adequately support lateral loads, preventing failures that could lead to catastrophic consequences in urban environments or infrastructure projects.

Related terms

Passive Earth Pressure: The lateral force exerted by soil on a structure when the soil is being compressed or pushed together, typically when the wall moves away from the soil.

At Rest Earth Pressure: The lateral earth pressure acting on a retaining wall when there is no movement between the wall and the soil, representing an equilibrium state.

Rankine's Earth Pressure Theory: A theory that provides a method to calculate active and passive earth pressures based on the assumption of horizontal backfill and no wall friction.