Terminology

Active forces or pressures - refers to the driving earth forces caused by soil and surcharges acting behind the wall. In the analysis results, these are typically separated apart from the hydrostatic and hydrodynamic forces that develop in the same region, unless they need to be considered together.

Backfill - refers to the region of soil that is filled behind the section geometry in the backslope region after the wall is constructed. If it is a reinforced wall, this will be the region behind the reinforced region. Otherwise, it is simply the region behind the wall.

Backslope topography - the ground surface profile behind the wall in a wall section, starting immediately behind the back of the highest layer or edge of the wall.

Front face topography - the ground surface profile in front of the wall in a wall section. A height of embedment is typically required in front of the wall, regardless of whether or not it is considered to provide passive resistance.

Hydrostatic force or pressure - refers to the static force of water below the water table, either behind or in front of the wall. It acts normal to the assumed failure plane (perpendicular to the surface on which it is exerted).

Hydrodynamic force or pressure - refers to the seismic portion of water forces acting either behind or in front of the wall. It is applied incrementally, which means that a separate static portion acts simultaneously. Note that in some cases, such as in AASHTO, a combined force may need to be calculated.

Leveling Pad - may otherwise be referred to as a "bearing pad," the supporting layer of gravel or other materials at the bottom of a block wall. In analyses of conventional segmental retaining walls, this provides some degree of dispersion to the vertical loads and increases sliding resistance.

Passive forces or pressure - refers to the restoring force from soil at the front of the wall. Note that not all design standards permit the assumption of passive pressure even if the wall is embedded to a certain depth. In the analysis results, these are typically separated apart from the hydrostatic and hydrodynamic forces that develop in the same region, unless they need to be considered together.

Wall - a container of wall segments defined along a polyline in the plan. There can be multiple walls in a model but their analyses will be separated.

Wall configuration - refers to the the arrangement (placement, location, orientation, elevations, etc.) of wall segments and the defining of wall sections to the segments.

Wall course - a single layer of blocks, baskets, or otherwise wall units within a wall section.

Wall section profile - refers strictly to the configuration of blocks, gabions, or geometry constructed in a wall section, not including stabilized soil or surrounding topography. It is the "mass" of the wall. It does not include the reinforced soil region in an MSE wall.

Wall section - the two-dimensional cross section of a wall segment, which is assumed to be a uniform extrusion along the length of the segment. Each wall segment will produce its own set of results during computations, and the results correspond to the wall section. It includes the backslope topography, surrounding soils, loads, groundwater table, etc. considered in the section.

Wall segment - the portion of a wall represented by a straight segment between two vertices in plan view on the wall configuration.

Wall unit - in segmental walls, the modular units that, when combined, make up the wall section profile.