Vibro Stone Columns (VSCs) offer an economical and sustainable alternative to piling and deep foundation solutions; removing the need to by-pass problem ground by densifying and strengthening weak or poorly compacted soils in-situ.

Basic Technique

A vibrating poker known as a 'vibroflot' is fitted to a purpose-built vibropiling rig and is used to penetrate the ground. Penetration is achieved using the vibroflot's own mass, the 'pull-down' facility of the rig (when used) and pressurised air flushes. All our rigs are fitted with our Data Logger computer system to monitor column installation.

Top Feed Method

Once refusal or design depth is reached the vibroflot is withdrawn and charges of graded stone aggregate are tipped into the bore hole from the surface; this is known as the Top Feed Method.

The vibroflot is then re-inserted to compact the stone into the surrounding soils. In granular soils the effect of the vibratory action produces a marked improvement in the density of ground, significantly improving the bearing capacity and settlement characteristics of the soils. In cohesive soils the columns act as reinforcement and provide a drainage path for excess pore water pressures to speed up consolidation times.

 vibro top feed

Bottom Feed Method

Where a high water table or weak soils are present the collapse of the bore hole is much more likely when the vibroflot is withdrawn. In these conditions the purpose-built Bottom Feed system is used to ensure integrity of the stone column from top to bottom. The vibrorig is fitted with a hopper which feeds stone into a 'tremie' pipe running down the length of the vibroflot.

vibro bottom feed

Strengths

Ground Improvement techniques contain no cement, concrete or steel, considerably reducing the carbon footprint compared to other traditional forms of foundation solution.

Virtually no spoil produced, which in turn reduces the amount of plant traffic on local roads and associated costs.

Locally-sourced and recycled aggregate can be used in the Vibro Stone Column technique (e.g. site-won crushed concrete)
High frequency vibrations mean the Vibro system can generally be used close to neighbouring buildings, subject to survey .

Generally the most cost-effective solution when dealing with poor ground, Vibro schemes typically offer a 50% saving over 'traditional' foundation solutions.

The productivity of the VSC technique on site significantly reduces programme time both in terms of the installation and the follow on trades - foundations and floor slabs are much quicker and cheaper to construct compared to those required after traditional piling installations.

 

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Quinn Piling Limited is a limited company registered in Northern Ireland. Company Registration No. NI041458
Registered Office: 15 Enterprise Avenue Down Business Park 46 Belfast Road Downpatrick BT30 9UP