Remediating collapsed retaining walls on building sites
19 February 2018
Mainmark:
As construction companies look to
utilise every inch of land when planning new developments,
retaining
walls are becoming an even more integral part of site works. Indeed,
many projects are featuring increasingly high retaining walls to
maximise their construction outcomes.
As retaining wall heights increase, so too does the potential impact of
a wall collapsing. The issue can put lives at risk and expose ajoining
properties to significant structural damage, as was the case in November
last year, when the retaining wall at a multi-storey development site in
south-east
Queensland collapsed causing serious structural damage to
neighbouring
buildings and the evacuation of residents.
The higher the wall, the more likely things can go wrong and issues can
escalate if gas,
power or
water pipes are affected. Drainage is also
important. If water can’t escape from behind the wall it will create
pressure which can increase the wall’s lateral load from 800kg to 1800kg
per metre of height (based on the lateral load of non-cohesive soil
versus saturated non-cohesive soil). This can create a precariously
dangerous situation.
In emergencies, a fast
remediation process is required to re-stabilise
the area. This process can often require substantial excavation and
backfilling, yet in situations where time is critical, traditional
backfill materials, such as concrete and aggregate, can be cumbersome to
use, particularly if the site is hard to access or on steep sloping
ground.
This is where solutions such as our Terefil® lightweight cementitious
fill, and Teretek® resin injection, can benefit engineers and builders
when there is a need to backfill, remediate or support a retaining wall
quickly without compromising its structural integrity or strength.
Terefil, which is available in permeable or impermeable form to suit
specific site conditions, is ideal as a backfill for retaining walls
during construction or after a new wall has been built. It forms a
stable block without disturbing or redirecting natural water flow and
its light weight minimises pressure on the wall when compared to heavier
granular fills. Once in place, Terefil can withstand heavy loads,
including large machinery and vehicular traffic, to allow construction
works to continue.
The Terefil formulation is highly flowable. Its pumpability is able to
reach more than 620 metres and can be placed at 70 cubic metres per
hour. Terefil is also environmentally inert, uses much less water than
traditional cemititious fill solutions and, is extremely cost effective.
Sampling and compression tests carried out to Australian Standard
AS1012.9 confirms Terefil’s permeability is in the range of 0.53cm to
0.087cm per second and has a compressive strength from 0.5 to 0.6 MPa,
once it has cured.
Teretek engineered resin also provides an immediate solution for
stabilising a partially collapsed retaining wall or where there is a
need to increase the strength of the ground and reinforce the toe of a
retaining wall.
Teretek is a two-in-one innovation that delivers both ground improvement
and re-levelling. When injected into retaining walls, the resin
components mix together and expand, strengthening and re-supporting the
wall’s footings without the need for any undue demolition or excavation.
Teretek can also be used as backfill or to consolidate any fill material
to help protect and strengthen a newly rebuilt retaining wall.
In the event of a retaining wall collapse, our team of engineers can
assess a site’s individual requirements and tailor a fast and cost
effective solution.
--ENDS--
Source: Mainmark - www.mainmark.com
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