E2445 Soil mechanics IV CIVL4320 Advanced soil mechanics Assignment 1 – Retaining wall © Dr Robert Day, The University of Queensland, 2018 CIVL4230 Advanced soil mechanics Assignment - Retaining wall...

E2445 Soil mechanics IV
CIVL4320 Advanced soil mechanics Assignment 1 – Retaining wall
© Dr Robert Day, The University of Queensland, 2018
CIVL4230 Advanced soil mechanics

Assignment - Retaining wall
Purpose: To compare different methods of design of a sheet pile retaining wall
Assignment Due: Refer to the course profile
Introduction: The alignment of a new
oad requires a permanent cutting of
varying depth. Because of restrictions to
the width of land available for the road, a
permanent concrete retaining wall is
equired to support the cutting. The
contractor building the wall wants to
construct a temporary steel sheet pile wall
to facilitate easy access for construction of
the concrete wall (see figure). You are a
consultant advising the contractor on the
design of the sheet pile wall.
Problem definition:
 Additional data is provided on the next page.
 Give your design for BOTH:
1. A cantilever wall which may be used for heights up to of 3.3 m constructed entirely
within the surface gravel layer. AND
2. A propped wall (shown above) for a retained height of 9.0 m

For the cantilever wall design
 Calculate the required depth of embedment using each of the following four analysis/design
methods:
Factor of safety methods:
o the simplified pressure distribution and Fp = 2
o the more simplified pressure distribution and Fp = 2
Limit state design methods:
o the simplified pressure distribution and  = 0.85 and LF = 1.25 and 0.8
o the more simplified pressure distribution and  = 0.85 and LF = 1.25 and 0.8
 If the length of the wall turns out to be more than 8 m, ignore the fact that the toe is actually
in the sand.
 Calculate the Serviceability Limit State bending moment. This is the same regardless of the
above method used.
 Calculate the Ultimate Limit State bending moment (for structural design) co
esponding to
each of the 4 analysis/design methods above.
 Select a suitable sheet pile from the table below assuming:
o Yield stress, fy = 270 MPa
o ULS capacity,Ms = 0.9 fy Z (I.E.  for structural design = 0.9)
 Briefly (no more than a few sentences or dot points) comment on the different results
obtained from the different methods of analysis.
 Summarize your results and comments on the Results Summary Sheet below.
9.0 m
2.0 m
8.0 m
Gravel
 = 38o
Sand
 = 30o
Ground water level
Permanent
concrete wall
Temporary
sheet pile wall
CIVL4320 Advanced soil mechanics Assignment 1 – Retaining wall
© Dr Robert Day, The University of Queensland, 2018
For the propped wall
 Use the geometry shown above and the Limit State Design method.
 Using the free earth method with  = 0.85, and LF = 1.25 and 0.8 calculate:
o the length of the sheet pile wall required for stability.
o the maximum ultimate bending moment (ULS) in the sheet piles.
 Calculate the maximum serviceability limit state (SLS) bending moment.
 Calculate the design anchor force (SLS and ULS) in the anchors.
 Select a suitable sheet pile from the table below (use fy = 270 MPa andMs = 0.9 fy Z).

Additional data for all designs
 Take the bulk unit weight b of all soil types to be 20 kN/m3
 Assume wall friction equal to '/2 on both sides of the wall. (Use the Caquot and Kerisel
earth pressure coefficient tables)
 Ignore the vertical component of earth pressure (due to friction on the back of the wall).
 Sheet pile wall section properties are given below.
Summarize your results on the attached summary sheet. This will help you to
compare and reflect on the differences between the methods.



Assessment criteria – Assignment 1

Criteria
Unsatisfactory / Poor
0 – 50%
Sound
50% – 75%
Good / Excellent
75% - 100%
Process
Intention unclear. Difficult
to understand. Lack of
understanding of problem
and theory.
Calculation methods
generally co
ect. Poorly
demonstrated and difficult
to follow.
Well presented and co
ect.
Clearly set out. Easy to
follow. Demonstrates
understanding of problem
and theory.
Accuracy
No solution to some
problems
Few solutions co
ect
within normal engineering
accuracy.
Solutions to most or all
calculations co
ect within
normal engineering
accuracy.
Discussion
Superficial discussion. Fails
to explain or understand the
issues.
Reasonably clear
discussion. Little
understanding of issues.
Clear, in depth and concise
discussion of issues.
Demonstration of insight
and good understanding of
issues and methods.

CIVL4320 Advanced soil mechanics Assignment 1 – Retaining wall
© Dr Robert Day, The University of Queensland, 2018
CIVL4320 Advanced soil mechanics Assignment 1 – Retaining wall
© Dr Robert Day, The University of Queensland, 2018
CIVL4230 Advanced soil mechanics

Assignment 1 - Retaining wall
Results summary sheet

This sheet must be completed and attached as the first page of your submission (under the EAIT
central assignment submission cover sheet).
Cantilever wall design
L – Length of wall (depth of embedment + retained height); BMSLS – Max bending moment – Serviceability
Limit State; BMULS – Max bending moment – for Ultimate Limit State design of the pile section

Simplified pressure
distribution
More simplified pressure
distribution
Factor of
Safety method
L L
BMSLS BMSLS
BMULS BMULS
Section Section
Limit State
Design Method
L L
BMSLS BMSLS
BMULS BMULS
Section Section
Comments:
Propped wall design

Limit State
Design Method
L Length of wall (depth of embedment +
etained height
PSLS
Prop force (1.85 x value from the limit
equili
ium calculation)
PULS
Prop force for Ultimate Limit State
structural design
BMSLS
Max bending moment – Serviceability
Limit State
BMULS
Max bending moment – for Ultimate
Limit State design of the pile section
Section