What type of retaining wall relies solely on its own weight and positioning to hold back soil?

The gravity wall is the correct answer because it is designed primarily to rely on its own weight and the force of gravity to resist the lateral pressure exerted by the soil it retains. This type of wall is generally constructed from heavy materials such as concrete or stone, which provide the necessary mass to counteract the forces acting upon it. Gravity walls are often wider at the base, tapering as they rise, which enhances their stability and ensures they do not tip over under the load of the retained soil.

In contrast, other types of retaining walls, such as anchored walls, utilize additional support systems (like cables or anchors) that are secured into the ground to provide stability against soil pressure. Sheet pile walls consist of interlocking sections driven into the ground to create a continuous barrier, which does not depend solely on weight but rather on friction and resistance from the surrounding soil. Counterfort walls include vertical reinforcing elements (counterforts) that help to stabilize the wall against soil pressure, distributing lateral loads back to the foundation.

Thus, the gravity wall's reliance on its own mass makes it unique among the types of retaining walls listed.