Table Of ContentDIAPHRAGM WALLS & ANCHORAGES
DIAPHRAGM WALLS & ANCHORAGES
Proceedings of the Conference organized by the Institution of Civil Engineers
and held in London, 18-20 September 1974
Institution of Civil Engineers, London, 1975
ORGANIZING COMMITTEE
M. W. Leonard (Chairman)
P. J. C. Buckley
R. W. Cooke
T. H. Hanna
C. K. Haswell
A. S. West
EDITOR
Thelma J. Darwent
© The Institution of Civil Engineers, 1975.
ISBN: 0 7277 0005 7
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permission of The Institution of Civil Engineers. ,
The Institution of Civil Engineers does not accept responsibility for the statements made or for the opinions expressed in the following
pages.
Published by Thomas Telford Ltd for the Institution of Civil Engineers at 26-34 Old Street, London EC1V 9AD
Made and printed in Great Britain by William Clowes & Sons, Limited, London, Beccles and Colchester.
Contents
Opening address, vii
SIR KIRBY LAING
Paper 'IT Practical considerations affecting the construction of diaphragm walls, z.
SLIWINSKI
AND W. G. K. FLEMING 1
^2. Diaphragm wall projects at Seaforth, Redcar, Bristol and Harrow, 11
F.'A. FISHER
/ 3. Diaphragm walls as load bearing foundations. . 19
H. KIENBERGER
4. In situ diaphragm walls for embankment dams. 23
A. L. LITTLE
Discussion on Papers 1-4 27
Paper 5. The properties of bentonite slurries used in diaphragm walling and their control.
M. T. HUTCHINSON, G. P. DAW, P. G. SHOTTON AND A. N. JAMES 33
6. A design study of diaphragm walls, 41'
E. L. JAMES AND B. J. JACK
7. Design and construction of a diaphragm wall at Victoria Street, London.- F. T.
HODGSON 51'
8. A load bearing diaphragm wall at Kensington and Chelsea Town Hall, London.
B. o. CORBETT, R. V. DAVIES AND A. D. LANGFORD 57
9. Model performance of an unreinforced diaphragm wall. w. j.
RIGDEN AND P. W.
ROWE 63
Discussion on Papers 5-9 69
Paper 10. Some practical aspects of diaphragm wall construction, 75
M. FUCHSBERGER
/ 11. Prefasif prefabricated diaphragm walls, 81
E. COLAS DES FRANCS
/ 12. Precast diaphragm walls used for the A13 motorway, Paris, 89
M. S. M. LEONARD
13. Temporary retaining wall constructed by Berlinoise system at Centre Beaubourg,
Paris, B. o. CORBETT AND M. A. STROUD 95
Discussion on Papers 10-13 - 103
Paper 14. Measured performance of a rigid concrete wall at the World Trade Center, s. K.
SAXENA 107
15. A case history study of multi-tied diaphragm walls. s.
G. LITTLEJOHN AND I. M.
MACFARLANE 113
16. High anchored wall in Genoa. 123
G. BARLA AND C. MASCARDI
17. Some experiences with ground anchors in London, j. 129
M. MITCHELL
Discussion on Papers 14-17 135
Paper 18. Construction, carrying behaviour and creep characteristics of ground anchors.
H. OSTERMAYER " 1 41
19. Behaviour of inclined groups of plate anchors in dry sand. w. j.
LARNACH AND
D. J. MCMULLEN 153
20. Experimental excavation of length 50 m supported by strutted cast diaphragm
walls: an analysis of stress distribution in the struts, 157
R. KASTNER AND P. LAREAL
21. Permanent anchored wall in Caracas, Venezuela, s.
PETRINI AND A. MILA DE LA
ROCA 161
Discussion on Papers 18-21 165
Paper 22. Economics of basement construction, 171
M. J. PULLER
23. Anchored walls adjacent to vertical rock cuts. 181
R. E. WHITE
24. Contiguous bored piles, j. p. 189
NORTH-LEWIS AND G. H. A. LYONS
25. Ground anchored sea walls for Thames tidal defences, j.
K. PICKNETT, D. L.
GUDGEON AND E. P. EVANS 195
Discussion on Papers 22-25 203
Paper 26. Diaphragm wall specification, w.
G. K. FLEMING, M. FUCHSBERGER, O. KIPPS AND Z.
SLIWINSKI 207
Discussion on Paper 26 213
General discussion 217
Closing address, c. 221
VEDER
Conversion table 223
Opening address
Sir Kirby Laing, JP, MA(Cantab)
President of the Institution of Civil Engineers
I think the organizing committee is to be congratulated on the
work it has done. From the support that it has received from all
over the world it is obvious that a conference of this sort on this
particular subject is most apposite at the present time. Certainly
the support of so many authors of world-wide renown is most
encouraging.
While diaphragm walling in the sense of this Conference is in
fact new in the UK (the first application was the construction of
the Hyde Park underpass in 1967) we must remember that the
use of sheet piling, which in effect is diaphragm walling, started
almost beyond living memory.
It is not enough for a conference of this sort to report on past
achievements. It should look forward. I am therefore glad to
see references to methods of improving surface finishes, but I
am sorry not to see any comments about the noise of machines
which are used in the construction of diaphragm walls, nor about
conditions prevailing on sites where bentonite is in use. Also,
why no reference to the conditions prevailing on surrounding
roads when this type of construction is used in confined sites in
city centres ?
I think those of us involved in the construction of diaphragm
walls have a responsibility to our neighbours, and in this way we
civil engineers once again become involved in the affairs of the
environment.
I have much pleasure in declaring the Conference open and
trust that all participants will benefit from the discussions that
will take place.
vii
PAPER 1
Practical considerations affecting the
construction of diaphragm walls
Z. SLIWINSKI, BSc, MICE, Consultant, Cementation Piling and Foundations Ltd
W. G. K. FLEMING, BSc, PhD, MICE, Projects Manager {Technical), Cementation Piling and Foundations Ltd
This Paper traces briefly the development of cast in place tion of equipment and the method rapidly became econo
concrete diaphragm walls and sets out to draw attention to mical.
some practical points which need consideration, discussion or 3. The first slot excavations, combined with reinforced
further research. ''The practical limitations of the method, in concrete structures, were used only about 20 years ago.
relation to such items as the concentration of the suspension A present assessment of the total area of such diaphragm
necessary to avoid excessive fluid loss, the stability of trenches walls in the world stands at some 6 to 7 million square
in soft ground, the methods of excavation which can be used metres.
in hard strata, and the problems which occur when the stand 4. The spectacular growth of the method may be
ing groundwater level is high, are discussed and some guidance attributed to certain factors. The first is the availability
is given. The behaviour and control of bentonite suspensions of bentonite, produced from montmorillonite clays, and
are considered in relation to the cycle of bentonite use and refined and converted to sodium montmorillonite for
the process of contamination of the fluid, including possible commercial use. Secondly, the technique is well suited
countermeasures which can be taken to reduce contamination. to a wide range of application. This includes cut-off walls
The problems of control on site using the available parameters under water retaining structures such as dams, weirs and
are enumerated, and the effects of allowing the properties reservoirs. In such cases the wall may be rigid (concrete)
of the fluid to go outside certain defined safe limits are stated. or plastic (concrete and bentonite mixture) and load
The desirable properties of concrete for placing by tremie are carrying capacity is not required. The range also includes
reviewed and details of a suitable basic mix are given. From load bearing and earth-retaining walls for a variety of
the point of'view of design, consideration is given to the use applications such as underpasses, deep basements, under
of reinforcement, and to the development of shaft friction on ground stations, tunnels, docks and pump houses. The
the walls of a trench and end bearing at its base. The third factor contributing to growth of the method is
factors influencing choice of panel dimensions are defined, the development of trenching equipment, which frequent
and some suggestions are made about detailing. The perme ly takes the form of heavy clamshell grabs which may be
ability of walls is examined, taking into account both hydraulically operated, and which can be attached to
the concrete of the panels and the performance of the joints. standard crawler crane units. Also relevant is the develop
Tolerances are also discussed with reference to verticality, the ment of plant for processing bentonite suspensions, now
finished wall face, the top surface of the concrete as cast often including equipment for efficient mixing and for
and the positioning of recesses. Finally, some of the risks desanding. Finally there is the economy of the method
associated with the process of diaphragm wall construction as compared with more traditional methods, often saving
are examined, including those associated with stability of time because of relative simplicity and saving cost because
the trench and possible settlement of the adjacent ground. of the incorporation of diaphragm walls into permanent
structures.
5. However, it must be recognized that there is still
much to learn and, although the views of specialists are
INTRODUCTION
broadly in accord, the technology is still developing.
Bentonite suspensions have found a substantial and con
In some directions, where we would wish to depend on
tinuing use in oil well drilling. They allow deep boreholes
established facts, only enlightened opinion is available.
to be stabilized when lining is impractical and they also
The object of this Paper is to raise some of the practical
serve to convey bored materials to'the surface. For such
problems which are in need of further research or exchange
applications' they have been subject to detailed study.
of views between engineers and contracting specialists.
In the field of soil mechanics, bentonite has long been of
interest because of its curious behaviour in forming thixo-
tropic suspensions.
2. The first use of the material in the -construction
PRACTICAL LIMITATIONS OF THE METHOD
industry to form retaining walls appears to have been in
boring contiguous piles by direct or reverse circulation Loss of bentonite
methods. The real breakthrough in the development of 6. One of the basic functions of bentonite suspension
the technique came when it was found possible to use is to form a filter cake skin on the surface of the soil ex
grabs for direct excavation, using the fluid only to support posed by excavation. The skin will form only if the fluid
the sides of a trench or pile. This gave rise to a simplifica- pressure in the trench exceeds any external groundwater,
o
Diaphragm walls and anchorages. Institution of Civil Engineers, London, 1975, 1-10 1
Paper 1
pressure and if the permeability of the soil is within cer Very soft soils
tain limits. 9. Experience shows that, in soils of very low strength,
7. A normal 4-6% concentration of suspension will it may not be possible to form diaphragm walls by con
be retained by ground having a permeability k up to ventional methods, because the internal bentonite pressure
about 10"1 or 10~2 cm/s as defined by Darcy's law. If the in the trench may be less than the active pressure of the
ground is more open than this a denser suspension in the soil. However, the examination of stability is not straight
range up to about 12% may prove satisfactory. In extra forward since panel length, shape and arching effects
ordinary cases, where even this dense fluid is not retained, modify the normal two-dimensional considerations. Any
a number of additives may be tried as indicated in Table 1. soil exhibiting strength parameters <j> (angle of internal
None of these methods is likely to be very effective if friction) = 0 and c (cohesion) < 10 kN/m2 should be con
permeability exceeds about 5 cm/s. sidered with caution; panels should be kept short, and
8. As filter cake formation is dependent on fluid loss without complications such as arise with the use of counter
is is not normally possible to find any significant filter forts. Conditions of instability are most prevalent in soft
cake formation in low permeability soils such as clay. marine clays and in fresh hydraulic fills.
Pieces of clay from the faces of diaphragm walls, examined
during the subsequent main excavation, show little or no Hard strata
trace of bentonite as a rule. 10. Occasionally it is specified that a diaphragm wall
shall penetrate some distance into rock or semi-rock soils,
Table 1. Treatment for loss of bentonite and this can pose serious excavation problems. A stand
ard clamshell grab of the type used by many companies
cannot penetrate hard rock and even in soft rock its
Treatment Materials Function Comment
method used efficiency is considerably reduced. The penetration of
the grab depends on its design and construction, and more
Add inter Clay Particles car Not suitable if
specifically on its closing force and weight (Fig. 1). For
mediate size Silt ried into pores pores are very
particles to Sand or fissures large occasional hard layers, heavy chisels are used to break the
suspension causing block rock into pieces which the grab can collect.
age .
11. For penetration into hard rock the standard equip
Chemical Potassium Flocculates Once seal is ment may be replaced by a special percussive reverse
additive aluminate bentonite gel, made the fluid circulation machine, but its output can be painfully slow.
treatment Aluminium floes block may have to be
chloride pores renewed Figures of 0-1-0-5 m/h are sometimes quoted.
Calcium 12. For semi-rock materials such as marl, Cementation
use the clamshell grab, assisted by an auxiliary rotary
Cement/bento- Cement added Allowed to Mixture usu
nite mixture to fluid at penetrate ally supplied boring machine of the type used in large diameter piling
mixing areas of loss only to area (Fig. 2).
and then set of loss, and
area subse
quently re-ex High water table
cavated under
13. A high groundwater table may be a substantial
normal fluid
impediment to the construction of diaphragm walls. It
Fibrous Graded A suitable Trial and hampers the casting of guide walls and reduces the differen-
materials (used fibrous or mixture will error method
in oil drilling flake materials, bridge fissures with wide
work) e.g. plant and fill a wide selection
fibres, glass, range of pore range j many
1, rayon, cello sizes materials
1000 mm
phane flakes, effectively available under 1 Dia. 900 mm preborsd hole
mica, ground trade names
rubber tyres, from oil drill nexcavated ground
ground plastic, ing sources
perlite, nut - Excavated panel J-0-0
shells, etc.
Boulder
clay
Soft sifty clay with
traces of sand
±1
Laminated shale-
c = 10-20 MN/m2
Fig. 2. Example of excavation of a diaphragm wall panel
using preboring to overcome difficulty in grabbing through
Angle d • degrees
hard shale. {Plant used for grabbing: Gemtrencha with
Fig. 1. Uplift force on grab during closing cycle hydraulically operated grab 1000 mm size)
2
