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Figure 11.11. T-shaped gravity wall retaining wet fill (for other dimensions, see Figure 11.10)

Figure 11.11. T-shaped gravity wall retaining wet fill (for other dimensions, see Figure 11.10)

To counteract the additional horizontal pressure due to ground water, the wall's base has been widened.

Notes on Example 11.3

O The wall base has been widened in attempt to ensure that it is still satisfactory for DA1. Similar comments are applicable to aspects of the calculation to those given for Examples 11.1 and 11.2.

© Since the wall is now wider, both favourable and unfavourable vertical actions due to the wall's self -weight and backfill are increased.

© The presence of water in the backfill results in a more complicated pressure distribution on the virtual back and uplift on the base of the wall.

Example 11.3 T-shaped gravity wall retaining wet fill Verification of drained strength (limit state GEO)

Design situation

Re-consider the design of the T-shaped gravity retaining wall from the previous worked example. Constraints during construction prevent a drain being placed at the heel of the wall. Therefore, the drain will be positioned behind the wall stem to reduce water level in the fill to a depth dw = 1.5m below the retained surface. The base of the wall is increased to B = 4.3m wide but all other dimensions remain unchanged. Material properties are also unchanged.®

Design Approach 1

Geometrical parameters

Unplanned excavation AH = min(10% H, 0.5m) = 0.3 m Design retained height Hd = H + AH = 3.3 m

Characteristic vertical actions and moments due to self-weight® Wall base: WGk = Yck x B x tb = 32.3 kN/m

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