Ground improvement for reclaimed land.

The methods, and when they work

Vibrocompaction & vibroflotation

The workhorses for clean to slightly silty sands. A depth vibrator re-arranges loose grains into a denser state, typically verified by CPT — delivered as dry vibrocompaction or vibroflotation depending on the ground and water conditions. Fast, well understood and ideal for large hydraulic fill areas, provided the fill has the right gradation and fines content.

Dynamic compaction

High-energy surface impact for deep densification of granular fills, including fills too coarse or variable for vibrocompaction. Often the right choice where access is open and energy can be traded against depth.

Stone columns

Where the underlying soils are soft and a granular reinforcement plus drainage path is needed — improving bearing, accelerating consolidation and mitigating liquefaction in the surrounding soil.

High energy impact compaction (HEIC)

A specialised surface method using high-energy impact rollers or drop machines to densify granular fills in deep, uniform lifts — often the right answer where access is open and the fill is too thick or variable for surface vibration alone. Few teams run it properly; we have planned, trialled and certified HEIC campaigns.

PVD + surcharge

Where the problem is soft clay, not loose sand: prefabricated vertical drains accelerate consolidation under surcharge, turning years of settlement into months — provided the programme is designed around realistic soil parameters. The same thinking applies to drained reclamation approaches, where the seabed is pre-drained ahead of fill placement to buy back schedule later.

Beyond reclamation: transport corridors

The same methods serve rail and road embankments on soft ground, where residual settlement limits are the acceptance test — the ground improvement strategy is designed around the settlement allowed, not the settlement avoided. That is how embankments on adverse ground are built to tight construction windows and long-term differential settlement limits.

Trials before production

Every method needs proving before it is bought. We have planned, trialled and certified campaigns across the methods — vibroflotation, vibrocompaction, dynamic compaction and HEIC — including combination trials where a single method can't deliver. Each trial is verified by CPT: screening the fill for layers that will not densify, checking cone resistance against the specification, assessing liquefaction, and accounting for the time effect on cone resistance after treatment. The result is an acceptance basis calibrated to your actual material, not a generic target from a textbook.

Selection is a geotechnical decision

Method selection depends on grain size, fines content, depth of treatment, the target design state, liquefaction requirements and schedule. Getting it wrong is expensive: vibrocompaction applied to a silty fill that can't densify, or acceptance criteria set from silica-sand correlations on a crushable fill. See carbonate and pumice sands for why that matters.

QA/QC is where projects win or lose

• Method trials before production — acceptance calibrated to your material, not a generic target.
• Screening for layers that won't densify before a treatment area is accepted.
• Verification grids designed against the specification, not against convenience.
• CPT-based acceptance criteria that reflect the actual soil behaviour — including carbonate corrections where the fill is crushable. See carbonate and pumice sands.
• The supporting verification toolkit executed in-house: plate load tests (interpreted to strain modulus, including modulus-ratio checks where the specification requires them), in-situ field vane, permeability testing, field density testing, geotextile field testing.
• Inspection and Test Plans written and executed — the documentation stands up to review, because reclamation claims always get reviewed.

We have run ground improvement campaigns full time on site — specifying, monitoring and adjusting until the verification passes. That is the difference between a treatment plan on paper and densified ground that has been proven.