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Chapter 3
Hydraulically-Driven Push Piers
CHAPTER 3
HYDRAULICALLY-DRIVEN PUSH PIERS
3.2. Summary Description
FSI push pier systems utilize high-strength
round steel tubes and a load transfer bracket
(retrofit foundation repair bracket) to lift and/
or stabilize sinking or settling foundations,
or to provide additional capacity to existing
foundation systems. The foundation bracket is
secured against and below the existing footing
(under-footing bracket), to the side of the footing
or to the foundation wall (flush-mount bracket),
or underneath existing slabs (slab pier bracket).
Pier sections are then hydraulically driven
through the bracket and into the soil below
using the combined structural weight and any
contributory soil load as drive resistance. Pier
sections are added and driven until a suitable
load bearing stratum is encountered. At that
point, the structure either begins to lift or the
target pressure/load is achieved. The weight
of the structure is then transferred to the
foundation brackets, through the piers, and to
firm load bearing soil or bedrock. Typical under-
footing, flush-mount and slab pier brackets are
shown in
Figure 3.2.a
. A Model PP288 push pier
installation is shown in
Figure 3.2.b
.
3.2.1. Applications
Push pier systems are typically used for
underpinning existing structures in the following
applications:
• Stabilization of settled foundations or slabs
• Stabilization and lifting of settled foundations
or slabs
• Providing increased capacity (additional support)
for existing foundations or slabs
• Providing foundation support while adjacent
excavations are made
Figure 3.2.a
Left to right; typical under-footing,flush-mount
and slab pier brackets (no relative scale)
Figure 3.2.b
FSI PP288 push pier system
with an under-footing bracket