Vibro stone columns are used to improve the characteristics of shallow low strength and stiffness soils. Adopting a Vibro Stone Column approach allows the use of lightly reinforced ground bearing slabs, pads & strip foundations – offering significant cost efficiencies when compared against a traditional piled approach.
Through the combined effects of densification, and/or reinforcement Vibro Stone Columns can be successfully used to improve both fine grained (Clay) and coarse grained (Sand & Gravel) soils.
Columns are constructed using imported stone compacted in voids formed using a displacement process, resulting in zero spoil arisings. GeMech operate a fleet of top feed vibro stone column rigs, with fixed mandrels ranging in length from 4.5m up to 7.0m.
With prior approval Vibro Stone Columns can be formed using recycled aggregates, offering environmental sustainability benefits.
Vibro stone columns can be used on a wide range of construction projects, from low rise housing, commercial warehousing to large scale Civil Engineering.
Advantages
- Suitable for a wide range of soils profiles
- More cost effective than most other piling methods, particularly when the whole foundation package cost is considered
- Faster than other traditional methods of piling
- Zero spoil arising
- Minimal site preparation requirements in comparison to traditional piling methods
- Recycled aggregates can be used in column construction, offering environmental sustainability benefits.
A lesser understood benefit of vibro stone columns in fine grained soils (Clays & Silts) is the improved consolidation rate of the host soil after column construction, as the columns work effectively as vertical drains, reducing the time period required for achieving primary consolidation. Vibro stone columns can be used in tandem with static surcharging to provide efficient solutions on sites with challenging ground conditions.
The Vibro Stone Column Process
Ahead of commencement on site GeMech will complete a detailed ground improvement design and prepare a stone column layout based on a set of construction issue foundation drawings – supplied to GeMech in DWG format by the Client.
Step 1 – Prior to the rig arriving to site the client surveys the area for serviclevel andes a suitable working platform at either top of foundation level or underside of slab level, and drives a numbered pin into the working platform at each pile position.
Step 2 – A health and safety briefing will take place, the rig will be prepared to work, and moved to the first pile position.
Step 3 – Stone is delivered to site and tipped on the working platform, in a stockpile positioned close to the piling rig. GeMech will move stone from the stockpile to the individual columns using a 360 excavator.
Step 4 – The fixed mandrel, with an appropriate length with respect to the ground improvement design requirements, will be set up over the numbered stone column position. The mandrel is then progressed to a predetermined design depth, or refusal at a maximum hammer pressure.
Step 5 – Stone is placed in the void formed by the mandrel in a series of layers, with each layer successively compacted by the vibro mandrel during the column construction process.
The near surface section of column receives least degree of compaction during the construction process, this is not a concern for stone columns below pad foundations, as this section of material is removed during excavation. For columns below slab areas, it is important that the surface of the improved soil is subjected to heavy compaction prior to slab construction, in order to compact the material at the head of the stone columns.
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Our Testimonials:
We have always found GeMech to be professional, straight talking and a pleasure to work with.
Simon Blackledge, Commercial Director, Gr8Space Group
GeMech handle all aspects of our ground improvement projects together with transparency and professionalism.
Darren Faircloth, Faircloth Construction Ltd
GeMech have always been courteous, knowledgeable and honest throughout our dealings with them.
Charlie Barker, Deep Living London Ltd
I have always found all members of the GeMech team to be extremely customer focused, technically proficient and totally driven to provide the best possible service and quality on site.
James Sinclair, Blue Dot Construction
In a competitive market GeMech has always stood above the competition as an exceptional ground improvement solution provider.
Daniel Calnan, Kent Structures
We have worked with GeMech on a number of projects, both complex with restricted access and large housing schemes. They have always been pro active providing solutions and costings. They have delivered all of our schemes to programme.
John Reed, Capstan
Clear, professional & practical communication during the pre-construction phase allowed for a smooth operation on site. Correct methods of piling for the presenting ground conditions were discussed and employed, resulting on hitting programme targets aswell as budget constraints.
James Scott, Willmott Dixon
Talus Solutions Ltd enjoys a harmonious relationship with the team at Ge-Mech Ltd, working together on various industrial, commercial and private sector housing projects. We have found Ge-Mech to be dependable and competitively priced in what they do and always ready to assist.
Philip Halford, Talus Solutions Ltd
Having worked with Gemech for over 20 years, they have always provided a first class engineered solution for our schemes.
Julian Mitchell, Mitchell Design & Construction
From start to finish the GeMech team take care of everything from the initial design to bringing each project to a successful conclusion on site.
Mark Blackhurst, Barnack Estates UK Ltd
Capabilities/Advantages:
- Column depths up to 7.0m
- Pre-augering can be accommodated, if required, using GeMech’s owned fleet of piling rigs
- Extensive design and validation experience across a wide range of projects, incorporating both residential housing and large-scale commercial
