dw = — for H < 4m and dw = 1m for H > 4m which is less onerous than Eurocode 7's requirements.1

It is rare for the water table to rise to ground surface and thus Eurocode 7's requirement could be regarded as too conservative. When the natural water

Consideration is being given to changing Eurocode 7's requirements from a Principle ('shall') to an Application Rule ('should') in a future revision.

table can be demonstrated to come below formation level, it is advisable to assume less onerous water levels even in fine soils.

11.3.3 Wall friction and adhesion

The design angle of wall friction 5d may be taken as:

Sd = k XPv,d where (cv,d is the design value of the soil's constant volume (i.e. critical state) angle of shearing resistance. For pre-cast concrete walls supporting sand or gravel, k = 2/3 and, for cast-in-place concrete walls, k = 1.

As discussed in Chapter 10, it may be preferable to select (cv,d directly rather than calculate it from:


cv ,k where ( cv,k is the soil's characteristic constant volume angle of shearing resistance and y( is the partial factor on shearing resistance.

11.3.4 Passive earth pressure - favourable action or resistance?

A question of particular importance in the design of retaining walls is whether passive earth pressure should be regarded as a resistance or as a favourable action. As a favourable action, the characteristic thrust P k produced by the passive earth pressure would be multiplied by the partial factor Yc,fav, as follows:

Pp ,d = Yg , favPp ,k whereas, as a resistance, it would be divided by the partial factor YRe:

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