where K is the at-rest earth pressure coefficient; y the soil's weight density; q any vertical surface loading; and u the pore water pressure in the ground.

Eurocode 7 suggests that at-rest conditions should be assumed behind retaining walls in normally consolidated soils when the horizontal movement of the wall is less than 0.05% of its retained height (see Figure 12.14).

The earth pressure coefficient K0 is given in Eurocode 7 as: K0 = (1 - sin cp) x y/OCR x (1 + sin p)

(which is Meyerhof's20 formulation combined with Kezdi's21 modification for sloping ground) where 9 is the soil's angle of shearing resistance; OCR its over-consolidation ratio; and p the slope angle of the ground surface (see Figure 12.6 for sign convention).

12.4.4 Limiting values of earth pressure

Annex C of Eurocode 7 Part 1 gives guidance on determining limiting values of earth pressure for active and passive states. Unfortunately, expressions C.1 and C.2 in EN 1997-1 are solely for dry ground (and contain errors, as noted in the UK National Annex to EN 1997-122). The correct expressions are:

0 0

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