PIANC E-Magazine - PIANC AIPCN welcome
PIANC E-Magazine - PIANC AIPCN welcome
PIANC E-Magazine - PIANC AIPCN welcome
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7. REDESIGN OF CORE TO<br />
OVERCOME FAILURE MECHANISM 2<br />
The state of the existing core material was unknown<br />
during the design phase (as part of it was<br />
covered under a 500 mm thick deck). In addition,<br />
crawling in under the concrete deck naturally revealed<br />
no fines (as it was all washed out and protected<br />
by a layer of coarser rock that appeared to<br />
be to specification). Therefore, a design change<br />
became vital after construction commenced and<br />
after removal of the dilapidated concrete roadway.<br />
Owing to budgetary constraints the existing fine<br />
core material had to be incorporated into the new<br />
design. The core design between Ch 66 and Ch<br />
96 subsequently changed from the original tender<br />
design, by means of a Variation Order, to the following:<br />
• Reshape existing sand core and cover face with<br />
geotextile.<br />
• Overlay the geotextile with a 450 mm thick layer<br />
of 10-50 kg rock.<br />
• Overlay the 10-50 kg rock layer by a 1,000<br />
mm thick 10-500 kg rock layer. Thus, its profile<br />
would tie into the adjacent core profiles.<br />
• Overlay the 10-500 kg layer with a double layer<br />
1-3 t rock as per the tender design.<br />
• Overlay the 1-3 t rock layer with a single layer<br />
4-6 t rock as per the tender design.<br />
<strong>PIANC</strong> E-<strong>Magazine</strong> n° 144, November/novembre 2011<br />
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