Earth - pressure wedge

Providing a structure with a cantilever jump (foundation slab of cantilever wall, modification for reduction of earth pressures) is considered when computing earth pressures it is possible to compute earth pressures acting either on the real back of structure with the inputted angle of friction δ ≤ 2/3φ  or on an alternate back of structure. The alternate back of sheeting structure replaces the real broken one by a slip plane passing from the upper point of the back of wall towards the outer upper point of the jump and forms an earth wedge – see figure. A fully mobilized angle of friction δ  = φ is assumed along this plane. The weight of earth wedge created under this alternate back further contributes to loading applied to the structure. To introduce the alternate back of structure into the analysis it is necessary to select in the program GEO5 Earth pressures the option "Consider developing of earth-pressure wedge". In other programs the earth wedge is introduced automatically.

Calculation with and without earth–pressure wedge

Determination of earth–pressure wedge in case of active earth pressure

The slip plane of the earth–pressure wedge is inclined from the horizontal line by angle υ_a  given by:

The shape of the earth wedge in the layered subsoil is determined such that for individual layers of soil above the wall foundation the program computes the angle υ_a, which then serves to determine the angle υ_as. Next, the program determines an intersection of the line drawn under the angle υ_as from the upper right point of the foundation block with the next layer. The procedure continues by drawing another line starting from the previously determined intersection and inclined by the angle υ_as. The procedure is terminated when the line intersects the terrain or wall surface, respectively. The wedge shape is further assumed in the form of triangle (intersection with wall) or rectangle (intersection with terrain).

Fine Maintenance

Get unlimited
support and updates
for your programs!

» More about Fine Maintenance