Which type of bulkhead is described as an untied flexible structure?

The description of an untied flexible structure aligns with the characteristics of an untied flexible bulkhead. This type of bulkhead is designed to absorb and distribute lateral loads from soil and water without being restrained by ties or anchors. The flexibility of this structure allows it to adjust to changes in pressure or groundwater levels, which can result from buoyancy or soil movement.

An untied flexible bulkhead typically consists of materials that can bend under load, which helps to reduce the risk of structural failure due to excessive lateral pressures. Since these bulkheads are not anchored to the ground, they rely on their weight and flexibility to provide stability and ensure they remain in place. This is particularly advantageous in locations where soil conditions or other environmental factors may continuously change.

The option that describes another type of bulkhead, such as anchored or tied, involves the use of additional structural elements that provide additional support, which contrasts with the flexibility and lack of restraint found in an untied flexible bulkhead. Understanding these key design differences and their implications on structural behavior is essential for civil engineering applications associated with bulkheads and retaining structures.