July/August 2021 - 101

FEATURE ARTICLE
Anchor installation site at Tennessee Lock
De-Tensionable Anchors for Lock and Dam Load Increases
Dam anchors do not generally require
load adjustment during their service
life. However, this was needed for part of
the Chickamauga Navigation Lock and
Dam in Tennessee, which was commissioned
in 1940 and began to have
cracks in the concrete of the lock. By the
1960s, structural issues associated with
this cracking affected lock operation.
This article covers the unique
technical characteristics of five anchors
most recently installed by Brayman
Construction Corp. in one of the large
concrete blocks (Monolith 48) of the
Chickamauga Lock. These anchors are
61 strands and include an innovative
destressing system that was installed to
address the effects of concrete
expansion. The challenges are explored
of the design, installation and testing for
an adjustable load anchoring system of
considerable scale.
Dam History
Chickamauga Navigation Lock and Dam
is located on the Tennessee River, seven
mi (11 km) upstream of Chattanooga.
Owned by the Tennessee Valley Authority
(TVA), the facility includes 4 hydroelectric
units, 18 spillway gates and a
60 ft by 360 ft (18 m by 110 m) navigation
lock operated by the U.S. Army Corps of
AUTHORS Jeff Hopple, P.E., and James Gagliardi, P.E., Brayman Construction Corporation
DEEP FOUNDATIONS * JULY/AUG 2021 * 101
Engineers (USACE). USACE oversaw an
investigation in 2014 that confirmed the
presence of alkali-aggregate reaction
(AAR). In AAR, certain silica-containing
aggregates react with alkali hydroxide in
concrete; the reaction forms a gel that
swells as it absorbs water, causing degradation
and expansion.
The concrete expansion had caused
the need for increased inspections,
maintenance and major construction
projects. As a result, the existing lock
was previously reinforced with over 300
anchors and is heavily instrumented.
Expansion of the concrete has exceeded
1 in (25.4 mm) vertically in places. The

July/August 2021

Table of Contents for the Digital Edition of July/August 2021

July/August 2021 - Intro
July/August 2021 - 1
July/August 2021 - 2
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