Stephen Baxter - General Manager
The McArdle Group provides ground engineering services to a broad range of clients in the civil engineering, building and infrastructure sectors of the construction industry. The improvement of soils by ground engineering processes increases the shear strength of marginal soils, resulting in a significant improvement of the bearing capacity and settlement performance of the improved soils.
With our in-house capabilities and specialised plant, our ground improvement services include:
- Soil stabilisation, soil modification and encapsulation
- Cement bound materials and bentonite enriched soil
- Piling platforms and stabilised sub-base and capping
- General civil works and associated earthworks
- Gabion baskets and embankment slip repair
- Retaining structures and walls
- Slope stability and reinforced earth embankments
- Vibro stone columns and vibro compaction
- Prefabricated vertical drains – band drains or wick drains
- Vacuum consolidation
- Landfill gas venting and leachate dispersal
- Impermeable liners for landfill cells and caps
- Full design and build foundations solution for problem sites
The main processes of our ground improvement systems are described in more detail as follows:
Soil stabilisation and modification
The feasibility of modifying very low strength soils into engineering fill by the addition of lime / slag / cement / bentonite or a combination of these is determined initially by in-house laboratory testing of the host material. The soils are modified in-situ using Wirtgen or Stehr rotivators or ex-situ and stockpiled for reuse. This specialised plant can also be utilised to encapsulate contaminated soils by the addition of various chemicals.
Vertical band drains
Band Drain Rig
Accelerated consolidation of alluvial soils is achieved by the installation of prefabricated drains with a polypropylene core wrapped inside a filter jacket which allows the necessary pore-water pressure release which can be expedited by an imposed surcharge to enable earlier development of the site.
Band drains are also used on landfill sites to facilitate gas venting, dispersal of leachate and with the added benefit of promoting settlement. Vacuum consolidation realises similar results to, and is an alternative solution to, band drains in circumstances where surcharge is impractical and a more rapid rate of consolidation is required.
Retaining Structures
Reinforced earth methods are used in the construction of slopes between 1 in 2 and 1 in 1 and utilise selected Class 1 or 2 fill with geogrid reinforcement, timber crib, gabion baskets, concrete blocks or a facing system using geocell for topsoil retention, as appropriate, depending on the structural or aesthetic requirement.
Embankment reconstruction due to slope or shallow seated failures can be achieved using lime/cement modification to enhance the engineering properties of the in-situ materials and/or with the use of geogrid reinforcement dependent on the embankment geometry.
Landfill works
McArdle Barrier Lining Systems Ltd supplies and installs geosynthetics for ground improvement projects, including onsite landfill, waterproofing membranes and specialist installation of landfill leachate pipework. The installation capability includes the associated earthworks, installation and welding of all geomembrane products utilising directly employed operatives accredited by the British Geomembrane Association, TWI and CSWIP.
Vibro stone columns
The construction of a highly compacted stone column and the resulting in-situ displaced soil form an integrated system having low compressibility and high shear strength with a resultant increase in bearing capacity enabling lightweight structures and low rise housing to be constructed without the need for expensive piling solutions.
In granular and mixed soils the stone columns densify the surrounding soil whereas, in cohesive soils, the stone columns, often stronger than the surrounding soil, act initially as reinforcement with excess pore water pressures being dissipated through the stone column to achieve rapid consolidation.
Full solution
The McArdle Group has over two decades of experience in geotechnical processes and can offer a full design solution to complement our in-house laboratory testing expertise.
Our team provides advice and extensive input into the design for ground improvement schemes in a wide range of developments, including:
- Land reclamation projects
- Housing development sites
- Commercial and distribution warehouses
- Development of urban and industrial sites
- Construction of roads, railways, airfields and dykes
- Preloading of tank sites and sites for storage of aggregates
- Harbour construction
- Landfill gas and leachate recirculation
Find out more
Contact us today and find out more about our ground improvement services
Read ground improvement project case studies
