Retaining Structures - Elements of Soil Mechanics - page 245

Example 8.4: Anchored sheet pile wall

If an anchor is placed 1 m below the ground level behind the sheet pile wall described in
Example 8.3, calculate the minimum depth of embedment, d, to provide stability using:

(a) Eurocode 7, GEO Limit State, Design Approach 1;
(b) gross pressure method, taking F p , the factor of safety on passive resistance, as equal
to 2.0.

Solution:

(a) Eurocode 7, GEO Limit State, Design Approach 1
As before, allowance is made for a future unplanned excavation Δ a equal to 10% of
the clear height. This is the height between the ground surface in front of the wall
and the anchor ( = 0.4 m). The pressure distribution is shown in Fig. 8.17.
1. Combination 1 (partial factor sets A1 + M1 + R1)
From Table 7.1: γ G; unfav = 1.35; γ φ ′ = 1 0 . .

From before, K a = 0.333, K p = 3.0.
Design actions:
The active thrust due to the earth pressure is a permanent, unfavourable action:

1
2

P = × × × + K γ ( d 5 4 . )

2

× γ = 4 5 . ( d + 5 4 . )

2

a d ; a G unfav ;

The passive resistance is also considered a permanent, unfavourable action:

1
2

P = × × × × 60 d d γ = 40 5 . d

2

p d ; G unfav ;

Effect of actions:
d is obtained by resolving the moment equilibrium equation. The lever arms about
A are:

2
3

l

a =

( d + 5 4 . ) − 1

2
3

l

p =

d + 4 4 .

∑ = 0

Fig. 8.17 Example 8.4.