OWNER:
Base Build Services Ltd
ENGINEER:
Baynham Meikle
GENERAL CONTRACTOR:
Base Build Services Ltd
MAIN FIGURES:
c.1,150 Controlled Modulus Columns & c.1,600 Vibro Stone Columns
Project Details
Menard was invited to provide a quotation for ground improvement works for a large industrial facility, following a prior site visit where Vibro Stone Columns (VSCs) had been installed beneath three smaller units. The site had a complex history, previously occupied by a company producing lubricants and hydrocarbons. This led to significant ground contamination, requiring extensive remediation including soil and groundwater treatment to meet regulatory standards. A unique aspect of the project was the close link between construction and operation. The company overseeing the development was both the contractor and the end user, ensuring high standards from ground preparation to final construction.
Ground Conditions
Following remediation, further ground preparation ensured stable ground conditions. Silty clay soils within the building’s footprint were excavated to a depth of 4.0 metres, removing unsuitable materials and optimizing the ground profile for engineering work. A structured layering system was introduced to enhance stability. First, a 300mm crushed limestone base was placed, followed by a 225mm sand layer to improve drainage and uniformity. Excavated silty clays were then re-engineered and compacted in controlled layers, with California Bearing Ratio (CBR) testing verifying strength at each stage. Cone Penetration Tests (CPTs) across the structure’s footprint provided crucial geotechnical data, shaping the design of ground improvement works by assessing soil strength, composition, and stability.
Solution
After evaluating the site’s geotechnical conditions, a combination of Vibro Stone Columns (VSC) and Controlled Modulus Columns (CMC) was chosen for ground improvement. VSCs were installed beneath the floor slab to enhance soil strength and mitigate settlement risks, achieving a bearing capacity of 65 kPa at depths of 4.0m to 6.5m. CMCs, placed at depths of 4.5m to 6.7m, reinforced structural foundations with an improved bearing capacity of 200 kPa, ensuring long-term stability. This integrated approach provided a cost-effective, robust foundation system, minimising settlement risks. Long-term residual settlements were kept under 25 mm, with relative differential settlements controlled at 1/500. Plate load and dummy footing tests confirmed compliance with design standards. The work was efficiently completed in three weeks using 1 VSC rig and 1 CMC rig.
