Alaska Residential Contractor Endorsement Practice Exam

Retaining walls that are free to move and rotate at the top should be designed for active pressure. Active pressure refers to the lateral pressure exerted by the soil when a retaining wall is allowed to move away from the backfill. This movement is a result of the wall's ability to rotate and shift, which reduces the pressure exerted by the soil compared to conditions when the wall is rigidly held or restrained.

When a wall is designed for active pressure, it takes into account the potential for movement, allowing it to accommodate dynamic forces without failing. This is essential because as the wall moves, the soil behind it exerts less force due to the physical adjustment of the soil particles. The concept of active pressure is critical in ensuring that the design of the wall appropriately considers its movement and the resulting variation in lateral forces.

In contrast, static pressure would not account for the movements of the wall, making it unsuitable for a design where movement is permitted. Earth pressure and shear pressure also do not specifically address the dynamic nature of the forces acting on a free-moving retaining wall. Thus, the correct focus on active pressure in this context is crucial for effective design and stability.