What are the methods used to support earth walls during an excavation?

The correct answer highlights essential methods commonly utilized for supporting earth walls during excavation, which are crucial in preventing collapse and ensuring safety during construction. Slurry walls, interlocking steel sheet piling, and steel soldier piles are all techniques that provide strong structural support.

Slurry walls are created by excavating a trench and filling it with a mixture of water and clay or other materials. This creates a barrier that stabilizes the soil and reduces water infiltration during excavation, helping to prevent erosion and collapse.

Interlocking steel sheet piling consists of long, vertical steel sheets that are driven into the ground and interlocked with one another, forming a continuous wall. This method is effective in creating a stable barrier against soil movement and is often used in areas with loose or saturated soil.

Steel soldier piles are vertical structural elements that are driven into the ground and typically used in conjunction with a lagging system to retain earth. By providing lateral support, soldier piles are instrumental in maintaining the integrity of the excavation site.

Other options presented do not align sufficiently with standard practices in excavation support. For instance, the use of wood planks and chain link fencing may not provide the necessary strength and stability needed for earth walls, and methods like gravel fill might not directly support earth walls during excavation but