1. EAG346-Sem II 2014/2015 Lesson 2

2. Problem
You will be given a cross sectional profile where a slope will be cut, a retaining wall will be constructed, and on an adjoining plot of land a fill will be laid.
The Site Investigation (SI) data for points along the cross sectional profile will be provided.
You will design the:
1. Slope
2. Retaining Wall
3. Foundation
4. Fill
5. Protection against erosion - Sedimentation control - General mitigation

3. SI1
a cross sectional profile with SI points
– FROM A PREVIOUS YEAR
SI points
Soil
SI2
Bed Rock
SI3
Clay
Sand
Bed Rock

4. a slope will be cut, a retaining wall will be constructed, and a fill will be laid – SI positions as indicated
Batter Face
Platform
Berm
Soil
Retaining Wall
Platform
Fill
Bed Rock
Clay
Geometry
Sand
Bed Rock

6. Slope Geometry

7. Slope Design Batter face Berm Toe Crest
Steepest acceptable by JKR for unsupported face < 9 m: 1:1 (next 1:1.5)
Steepest acceptable by JKR for unsupported face > 9 m: 1:1.5 (next 1:2)
Height (vertical berm to berm) 5 m or 6 m only
Berm
2 m or wider
Berm drain
Toe
Toe Drain
Crest
Factor of Safety (Local and Global)
1.5 in civil engineering or 1.25 in mining engineering
Batter Face
Crest
Berm
Toe

8. 1
1.5

9. Aspects of a Retaining Wall
Stem and Base proportioning
Toe and Heel
Backfill
Height of backfill
Flat or incline backfill
Foundation (shallow or pile)
Drainage (weep holes and drain)

10. Retaining wall resting on shallow (sub grade) foundation
Active, Passive, or at Rest

11. Retaining wall resting on pile foundation
Active, Passive, or at Rest

12. Retaining wall resting on pile foundation
Batter Face
Platform
Berm
Soil
Retaining Wall
Platform
Fill
Bed Rock
Clay
Sand
Bed Rock

13. Batter Face
Retaining wall resting on pile foundation
Berm
Platform
Soil
Retaining Wall
Fill
Bed Rock
Clay
Sand
Bed Rock

14. Retaining Wall Analyses (and normally acceptable FOS)
Stability against sliding
Least FOS=2
Stability against toppling
Stability against bearing failure
Shallow foundation (FOS=3)
Deep foundation (piles)(FOS>2)

15. Retaining Wall Design
Active, Passive, or at Rest (Normally assumed active)
Dimensions and Reinforcement
Shallow Foundation enough?
Or Deep Foundation (piles) required?
If piles, how long, how many, how big, and what type – driven or bored (micropile)?

16. Dimensioning
Top of stem should be at least 0.3m to provide for concrete placement
Depth to the bottom of base slab should be at least 0.6m
Bottom of base slab should be below frost line
Width of base slab should be H
For cantilever retaining wall, the thickness of stem and base slab should be at least 0.1H
For counterfort retaining wall, the counterfort slabs should be about 0.3m thick and spaced at H
For gravity retaining wall the toe should be H wide and the heel should be H thick
For cantilever retaining wall, the toe should be 0.1H wide and the heel should be 0.1H thick