Handbook for Bridge Inspections - TSP2
Handbook for Bridge Inspections - TSP2
Handbook for Bridge Inspections - TSP2
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9.1 ELEMENTS IN THE GROUND<br />
•<br />
Clfklinallevel<br />
V<br />
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V<br />
V<br />
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B<br />
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7<br />
vi<br />
1,5 m<br />
Foundations on piles do not no rmally need ea rth masses under the foundations to achieve carrying<br />
capacity. Free-standing piles, on the other hand, will be vu lnerable to damage from ice, dtifnvood,<br />
rot and should there<strong>for</strong>e be protected. The figure above is based on the <strong>for</strong>mulae <strong>for</strong> calculating carry<br />
ing capacity detailed in the <strong>Bridge</strong> Manual and demonstrates how carrying capacity is reduced<br />
from 100% (at the original levei 'A ') to 50% (at new level 'S') when erosion. Should the erosion be<br />
allowed to continue up to level 'C', th en carrying capacity will be reduced to 25% of the o:riginal<br />
figure.<br />
Maintenance Costs<br />
Even minor damage to protective measures against erosion show a tendency to accelerate and become<br />
expensive to repair. It is important that protection against erosion be in working order especially<br />
in a flood situation, otherwise scouring can arise with resultant severe co nsequences <strong>for</strong> the carrying<br />
capacity. Erosion above water level can offect the carrying capacity, traffic safety, majntenance<br />
and the environm ent. The removal of earth masses from around abutment piers can lead t() reduced<br />
carrying capacity. Erosion can produce holes in the pavement wi th resultant risk to road users. The<br />
scope of the damage can increase markedly if measures are not taken to halt the erosion.<br />
L-<br />
Conditions which Trigger Maintenance Measures<br />
Maintenance measures must be undertaken immediately when erosion and particularly under-scouri<br />
ng of foundations have occurred underwater. Cases of erosion above the water line should be individually<br />
assessed by the inspector.<br />
Maintenance Measures<br />
Undenrarer :<br />
• Flushing out the water course<br />
• Repair of damaged erosion protection<br />
• Construct erosion protection<br />
• Replenishing earth masses below and around foundations with suitable material<br />
• Recasti ng of concrete under the foundations if the carrying capacity enables so. Found alions<br />
supported on pi les should be given special attention.<br />
Above /Va/erLeI'e1<br />
• Replenishing with suitable new materia ls<br />
• Covering em bankments w ith paving stones<br />
• Improvements to the drainage system directed fonvards removal of surface water.<br />
• Sowing seeds/planting to encourage binding of the soil.
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