Soil consolidation and land reclamation
On coastal reclamation works, a thick layer of granular reclamation material is applied to form the new land profile. Typically, the foreshore and seabed overlaid with this material is of a low quality alluvial material which may be poorly compacted and have low permeability. Variations in the depth of the weak soil and the differing depths of the reclamation mean that the finished reclamation profile may not settle evenly, and the presence of low permeability marine clays and silts will pose consolidation risks.
Allowing for consolidation can be a long process, lasting more than 25 years in weak saturated soils under surcharge loading. The solution lies in releasing the groundwater and reducing the pore water pressure as quickly as possible. To facilitate this drainage and accelerate consolidation, regularly spaced prefabricated vertical drains (PVDs) are installed to create shorter drainage pathways for the groundwater. This enables consolidation settlement to be completed while reclamation works and infrastructure installation are underway.
For shallow water reclamation or sea bed consolidation, the PVDs can be installed from a barge and cut off at sea bed level. The pore pressure is then released into the freely draining granular material placed in the reclamation works. For deeper reclamations, the drains are typically placed from the finished ground profile prior to placement of any additional surcharge fill.
Colbonddrain CX1000 prefabricated vertical drain is a geocomposite that resists tearing under load during installation. This maintains its integrity and thus supports the drainage pathway. The outer filter fabrics are bonded to the core structure over its entire surface to form a homogeneous geocomposite product.
Woven Enka-Force fabrics at the intersection of marine clay and hydraulic sand fill contribute to the stability of steep side slopes and avoid differential settlements.
Full consolidation of weak soils beneath the reclamation can be achieved in months rather than years when using Colbonddrain prefabricated vertical drains (PVD).
Functions:
- Soil consolidation
- Stabilisation
Relevant products:
