Acceleration of Consolidation
In an increasing number of situations structures are founded on considerable thickness of naturally or reclaimed soft cohesive deposits. The problem of the soft cohesive clays is its very slow consolidation, which often require years to achieve 90% or 95% consolidation.
To solve the settlement problem, the commonly used technique is sand drain. The purpose of this technique is to accelerate the dissipation of excess pore water pressure, so the settlement process will take shorter time. But, there are few problems on sand drain implementation, which are:
- The large diameter of sand drain cause disturbance on subsoil while installed
- Difficulty on getting sand material in uniform property
- Disturbance of water flow if the movement occurred
One of new technology that have been widely implemented to replace sand drain technique is the insertion of vertical wick drain. The benefit of this material are:
- The size of material relatively small, therefore the disturbance effect become minimum
- This material is uniform in its property because it is prefabricated
- Flexible, since the water flow isn’t disturbed if lateral movement occurred
Vertical wick drain makes the consolidation process become faster. This material provides vertical lane to dissipate excess pore water pressure from subsoil. The acceleration of the dissipation of the excess pore water pressures results in:
- A faster increases in the shear strength of the soil during construction, which permits the structure to be built with a minimum delay for stability reasons.
- Complete (or partially completed) primary settlement during the construction period, hence avoiding subsequent damage of the structure.
The principal of vertical drain performance are:
- Shorten drainage path; the path is horizontal into vertical drain material.
- Benefitted soil permeability which better in horizontal direction.
- REKLAMASI PANTAI MANADO, Manado – (Sulawesi Utara, 2002)