Ground Improvement Techniques

Dynamic Compaction

With dynamic compaction, the ground is subjected to repeated surface tamping using a heavy steel and concrete weight. Typically the tamper weighs between 5 and 20 tonnes, dropping in free fall from heights of up to 25 metres. The tamper is dropped a set number of times on a grid pattern over the site to form a pass. Two to five passes on a site, dependent on soil type and condition, can be required. The imprints formed at each drop position are infilled with granular material after each pass.

Vibro compaction

This process is used in fully saturated and very weak soils. Water jetting removes soft materials, stabilises the hole and allows the stone backfill to reach the bottom of the vibrator. This is then compacted and interlocked with the surrounding soil. This is a compaction process for purely granular soils.

Vibro replacement

To construct the stone columns, the vibrator is allowed to penetrate to the design depth and the resulting cavity is filled with hard inert stone, free of clay and silt fines. The required interaction between the stone columns and the surrounding soils, is developed by the stone infill being introduced and compacted in stages, each charge of stone being thoroughly compacted.

Other ground improvement systems include:

• Jet grouting
• Drains
• Ground Freezing
• Soil Stabilisation – Injection grouting (with and without TAM’s)
• Soil Mixing
• Vibro Concrete Columns