Pile Design and Construction Practice, Fifth edition

Piling equipment and methods 123

Similar base grouting techniques were used at six sites in the Docklands area of London
beneath piles with diameters in the range of 0.75 to 1.5 m(3.16).
Part of the internal plugs to the 2.50 and 3.13 m ODdriven tubular steel piles for the
Jamuna River Bridge(3.17)were cleaned out by airlifting which loosened the soil at the base.
In order to reconsolidate the remaining plug of sand a grid of tubes-à-manchette was placed
in the hole above the plug and a layer of gravel placed by tremie to cover the grout tubes.
A 7 m plug of concrete was placed over the gravel and 12 hours later, water was injected at
a pressure of 20 bar to lift the sleeves. Cement grout (40 litres of water, 50 kg cement, 0.35 kg
bentonite, and 0.5 kg plasticizer) was then injected into the gravel plug. Grouting was
terminated when the pressure reached 50 bar, in order to ensure that uplift of the pile would

Pile head

Pile base

500 mm

Tube à manchettes

Outside of

reinforcing cage

Perimeter

of pile

12 000 mm

Grout circuit

Inside of

reinforcing cage

PLAN OF PILE BASE

Steel tubing

64 mm internal diameter

Rubber sleeve

2 holes ∅∅ 4 mm

SECTION OF INDIVIDUAL

GROUT CIRCUIT

Figure 3.38Arrangement of circuits for base-grouting of piles (after Yeats and O’Riordan(3.15)).