Group B - Design of a retaining wall [10 marks]

Consider the retaining wall shown in Fig. 2 built in Melbourne. The wall must hold a 4.5 m high uncontrolled backfill of crushed gravel (d = 30°.

7= 20 kN/m³). A vertical live-load of 7.5 kPa is applied on the soil surface ( = 0.7.= 0.4). The soil below the footing is the same as the backfill. The

allowable bearing pressure is 150 kN/m², the concrete cover is 35 mm in the wall and 50 mm in the footing, the characteristic strength of concrete is 32 MPa,

and its weight density is 25 kN/m³. The reinforcement is D500N20.

VAVAVA

20°

Crushed gravel

144

0.8 0.6

Fig. 2- Geometry of the retaining wall

2.0 m

9-7.5 kPa

4.5 m

0.5 m

(3 marks) a) Determine the factored properties of the soil and active pressure coefficient to design the retaining wall.

(3 marks) b) Calculate the factored distribution of pressures acting on the wall and design the reinforcement required in the stem.

(2 marks) c) Discuss the different types of cracks that can appear in the retaining wall and sketch them using the geometry of Fig. 2.

(1 mark) d) Check the maximum stress in the soil below the footing.

(1 mark) e) Check the safety of the retaining wall against overturning and sliding failure modes.