The new Interstate 10 Twin
Span Bridge over Lake
Pontchartrain is being
constructed to replace the
existing Twin Span Bridge,
which was heavily
damaged by Hurricane
Katrina. The Louisiana
Department of
Transportation and
Development (LADOTD)
designed the new bridge to
be higher, bigger and
stronger than the existing
bridge and to last well into
the 22nd century. To
address several questions
raised during the design
phase of the project,
LADOTD decided to install
a long-term monitoring
system on one bridge pier
|
(M19 Eastbound) at the
main span. The
instrumentation for the
substructure of M19
Eastbound pier includes
strain gauges and
inclinometers cast inside
the foundation piles, water
pressure cells to measure
wave forces,
accelerometers to
measure lateral
movements of piles, and
corrosion meters in the pile cap rebar.
A unique lateral load test
was designed and
conducted to assess the
validity of the analysis
methods used to design
the pile foundations. Two
|
|
high strength steel strands were run through the pile caps of one pair of piers (M19 Eastbound and M19 Westbound). These cables were pulled with hydraulic jacks to impose about 2 million pounds lateral force between the two pile caps. Horizontal movements of the pier caps were monitored using an automated survey station with prisms. The strains and deformations within the foundation piles were measured using the strain gauges and inclinometers in the foundation piles.
Two of Geocomp’s
engineers, Da Ha and Francisco Trejo, installed the instrumentation, and tracked the construction of the piles from the fabrication yards in Memphis, Tennessee, to the docks in Slidell, Louisiana.
|
The installation was particularly challenging because thousands of feet of cables had to be threaded through the
|
|
|
|
