GGU-UNDERPIN: Double-bounded surcharges (active side)
If two bounded surcharges are defined as follows:

Figure 11 Two bounded surcharges
Bounded surcharge 1:
begins at x = 1,00 m and has the value p.Bounded surcharge 2:
begins at x = 2,00 m and has the same value as surcharge 1 but with a negative sign
(see the explanation on the previous page).
A double-bounded surcharge, which acts as a consequence of p at x = 1.00 to x = 2.00, is thus defined as the result of earth pressure analysis. However, the graphics are not really satisfactory and may be irritating for an examiner. Double-bounded surcharges were therefore introduced.

Figure 12 Double-bounded surcharge
The same result is achieved as for the definition provided by Figure 11 but with improved graphics.
The area loads described in Section “Area loads” are based on different assumptions for the resulting earth pressure, so the definition of a double-bounded surcharge does not provide the same result as an equivalent area load.