OWNER:
Portakabin
ENGINEER:
Structa LLP
GENERAL CONTRACTOR:
Kenward Construction
MAIN FIGURES:
150 Vibro Stone Columns
Project Details
Due to slab problem on the current Buckton Fields School, Portakabin and Kenward Construction approached Menard UK for a fast solution to build a new Portakabin school of a total floor area of 1,350 m². Due to the immediate need of the construction, Menard UK accommodated an early start for the new building to be construct as soon as possible. Portakabin required the treatment under the pads footing only, with different loads.
Ground Conditions
The site investigation revealed the presence of uncontrolled made ground above loose and medium dense sands. Made ground was found up to 2 m in the site investigation and was predominantly described as clay. There has been no groundwater encountered in the boreholes of the site investigation. The site was not developed before and no contamination have been found in the soil.
Solution
The presence of uncontrolled made ground and loose sands made impossible any construction without unacceptable residual and differential settlement. Due to the depth of treatment (up to 4 meters) and the soil conditions (no peat nor organic clays, with a competent dense sands layer beneath), Menard UK offered the use of Vibro Stone Columns (VSC).
This scheme enabled the construction of regular shallow foundations, notably pad footings with different allowable bearing pressure, hence providing significant savings compared to a piling option. Due to the number of pads and their associated loads, the total number of Vibro Stone Columns placed are 150. The VSC columns have been arranged under the pad footings up to 2 columns per pad. Menard UK has been able to quickly mobilise on site (less than 2 weeks between receiving the first enquiry and starting on site) and the 150 columns have been installed in 1 and a half day. Plate load tests have been carried out to verify the workmanship.
Sustainable Development
Vibro Stone Columns (VSC) is a very low-carbon solution because only stones (and no concrete) are used for the ground improvement and it allows the construction of conventional shallow foundations. Menard UK also sourced washed recycled aggregates to form the VSC columns, reducing the overall embodied carbon footprint of the solution.
