The document outlines the construction sequence for building a diaphragm wall. It involves: 1. Constructing guide walls along the perimeter to stabilize the soil and provide a guide for excavation. 2. Boring the diaphragm wall sections using a hydraulic grab in sequential sections. Polymer slurry is used to retain the soil. 3. Fabricating and installing the reinforced concrete cage by cutting, bending and fixing steel reinforcement, then lowering the cage into the excavated sections. 4. Concreting the diaphragm wall sections using a tremie pipe to fill from the bottom up to form a continuous wall. Anchors are then installed and stressed.

2.  Construction of Guide Wall along the periphery of Diaphragm wall.
 Boring of Diaphragm wall.
 Cutting/bending and Trading of reinforcement Steel, fixing of diaphragm
wall reinforcement cage & Cage Lowering.
 Concreting of Diaphragm wall.
 Anchor Preparation
 Anchoring to the Diaphragm Wall
 Stepwise Excavation for Basement .
 Dewatering..
Construction sequence to be adopted at site

3. Complete Construction Sequences of Diaphragm wall

4.  Construction of Guide Wall along the periphery of Diaphragm wall.
 The RCC guide walls shall be constructed as per the dimensions and with reinforcement as shown in
the drawing.
 Guide wall shall be 250 mm thick and 1.50m depth and made of reinforced concrete, and shall
represent the reference lines.
 Minimum clearance between finished diaphragm wall and guide shall be 25-50 mm.
 The finished faces of the guide walls towards the trench shall be vertical.
 Guide wall after construction should be suitably propped to maintain specified tolerance.
 The level of Polymer slurry in the trench shall not less than 1 m from the top of Guide wall.
 Guide wall get support from adjoining panels and therefore, their construction should be done
continuously.
 These guide walls stabilize the soil in the upper diaphragm level and provide a stable guide-way for
the grab.
Methodology to be adopted at site

5. Marking of Survey Reference for Guide Wall

8. Boring of Diaphragm wall.
Boring operation shall be started by using hydraulic/ mechanical grab in
sequential manner as per shape. First two Cut shall be extreme end of diaphragm
wall. 3rd cut shall be middle portion Diaphragm wall . Polymer slurry is used to
protect the sides of the soil. The slurry will produce a great lateral pressure
sufficient enough to retain the vertical soil.
Polymer Slurry Preparation:- Tanks of suitable sizes and slurry pump of suitable
capacity for storage. Mixing and circulation of Polymer Slurry at site. A separate
pump may be used for water supply to slurry tank. Equipment for sampling the
slurry from trenches and testing its concentrations, viscosity, pH value & hardness
of ground water in which the Polymer slurry and concrete are prepared.

10.  Boring of Diaphragm wall (Cont..)
 Joining for the diaphragm wall panel – Diaphragm wall cannot be constructed
continually for a very long section due to limitation and size of the mechanical
plant. The wall is usually constructed in alternative section. First panel is called
as primary panel in which two stop end will be placed at the ends of the
excavated trench before concreting. The stop ends are withdrawn at the same
time of concreting so that a groove can be formed. Wall sections are formed
alternatively leaving an intermediate section in between. The in-between
sections are built similarly afterward but without the stop end. At the end a
continual diaphragm wall is constructed with the panel sections tightly joined
by the groove.
1 st Panel
Panel progress Sequence Panel progress Sequence

11. Schematic drawing of Boring activity of Diaphragm
wall
Hydraulic Grab
Boring
(Stage 1)
Boring
(Stage 2)
Boring
(Stage 3)

12. Boring for Diaphragm Wall with Hydraulic HR-180 Rig

14. Boring for Diaphragm Wall

15.  Verticality check for Boring of Diaphragm wall:-
 Ultrasonic Instrument called Koden, shall be used for verticality check
of Bored diaphragm wall panels.
 The Deviation of the bore trench from the perpendicular and any
surface cavities in the bore hole or trench wall shall be measured.
 The ultrasonic measurement probe is suspended vertically from a cable
and lowered into the object to be surveyed.
 At the same time, orthogonal waves are continuously emitted from the
device and reflected from the walls.
 The reflected waves are registered by measurement sensors. The
distances, calculated as a function of wave speed and reflection time,
are presented in graphic form.

16. Verticality Checking with KODEN

17.  Reinforcement Fabrication for Diaphragm Panels:-
 Steel cutting , bending & fixing shall be done as per drawing. Proper laps, Dowels
shall be insure while fixing of cage.
 If required extra reinforcement shall be adequately provided fixed to avoid
displacement and to maintain minimum specified cover during concreting.
 Concrete Cover blocks shall be circular and tied to rebar cage at regular interval
 Welding shall be provided to avoid displacement while shifting, lifting & lowering.
 After ensuring the welding & safety checklist of entire cage, cage shall be lifted
with the help of cranes.
 Lifted diaphragm wall cage shall be lowered in bored trench of diaphragm wall.
 Cage shall be rest with help of resting bars on the guide wall.

18. ITD Cem

21.  Concreting of Diaphragm wall.
 Concreting:-Concreting shall be done by tremmie method
 Tremmie pipes shall be clean, watertight & with a minimum internal diameter of 200 mm
 Tremmie shall be lowered up to the bottom of the trench through the slurry column.
 After lowering tremmie the hopper will be fixed on the top of tremmie pipe & plug will be
placed bottom of hopper, after plugging the hopper will fill with concrete up to the top of
hopper then the tremmie pipe shall be raised slowly and remove the plug from hopper so
that concrete in a single continuous flow.
 Care shall be taken so that bottom end of tremmie pipe remains immerse at least 1.5 m below
in concrete during casting. Concrete shall be continued till the overflow at least 0.6 m over the
cutoff level of the Diaphragm Wall as shown on the drawing. Once concreting is started it
shall be continued without break. The permissible time gap between consecutive shall be so
adjusted that on initial setting of concrete takes place before it reaches its final position.
During concreting, continuous raising and removal of segments of tremmie pipes shall be
ensured.
 After reaching concrete its initial setting time, Stop end pipe shall be removed from the bore
and boring for secondary panel shall be started.

25. Removing of Stoppend by
Hydraulic Jack System
Removing of Stoppend by
Hydraulic Jack System.

26. Anchoring
 Sequence of Anchoring
 Setting of Drill Rig at Location and Align
 Driving Casing into Overburdens and Drilling for Fixed Length
 Initial Grouting of Drilled Holes
 Redrilling of Grouted Holes
 Water Testing of Redrilled Holes
 Fabrication of Cables
 Homing of Cable into the Drilled Hole and Fixed Length Grouting
 Stressing of Cable
 Grout the free length Portion
 Cutting extra Length of Strand and Concreting the Pocket

27. Setting of Drill Rig at Location and Align
 Suitable rig is shifted to the anchor location and the rig is positioned to drill a
selected hole .

28. Driving the Casing into Overburden and Drilling for
Fixed Length
 After the rig is positioned and aligned, drilling is taken up. Drilling of 150 mm dia.
hole in silty sand / clay shall be carried out by Rotary Percussive DTH system or
simultaneous casing driven method.
 After fixing the casing in overburden, further drilling shall be continued by rotary
percussive by using DTH. As soon as drilling reaches its desired depth, the drill tubes
shall be withdrawn from the hole and machine shall be shifted to next location.

29. Initial Grouting of drilled holes
 The drilled holes shall be pressure grouted with neat cement grout to fill the voids,
joints, fissures etc around the anchor hole and to reduce the permeability.
 Single packer with mechanically expanded rubber ring shall be fixed at the collar of
the hole. The minimum diameter of the grout intake pipe shall be 25mm. An
assembly with grout intake, bleeder valve, pressure gauge with gauge saver shall be
fixed on to the packer for grouting.
 The hole shall be taken for grouting and shall be grouted to refusal at required
pressure as detailed in the subsequent paras.
 After grouting is completed the packer is removed only after ensuring that there is
no back flow of grout from the hole.

31. Fabrication of Cable
The cable shall be fabricated using required calculated number of HT strands of 15.2 mm dia. with UTS as
per BS 8081: 1989.
 The HT strand shall be cut to required length.
 Bond length of the cable shall be cleaned and applied with two coats of epoxy and quartz sand shall be
sprinkled when the second coat is tacky to increase the bond strength.
 Free length shall be cleaned thoroughly and shall be applied with two coats of epoxy based paint.
 Cable shall be tied with GI binding wire by providing the MS spacer at regular interval to space the strand
in equidistance and in the bottom MS cap shall be provided.
 After tied up the cable, the HDPE duct shall be encased and plug the upper and bottom end so
that grout will not be leaked out.
 Free length, HDPE pipe (plain sheath) shall be encased to individual strand pushed with grease
and plugged the lower end with suitable PVC tape so that while grouting the bond length grout
will not be entered into the duct. After encasing the duct to the tendons, shall be tied with
providing spacer at 2.0 m C/c.

32. HT Strand Cut at Required Length

33. Application of Sand and Quartz

34. Fixing of Spacer , Grout Pipe, &
Tieng with GI wire

35. HDPE Ducting