Vibro stone columns (VSC’s) are a popular method of enhancing geotechnical properties of poor soils. VSC’s are suitable for the improvement of both weak natural soils and made ground. Typically, improved bearing capacities range from 50kN/m2 to 175kN/m2.
VSC’s are inclusions of a granular material which are formed in the ground, improving the load-bearing capacity and limiting both total and differential settlement. Stone columns can be installed in groups under isolated loads or directly under linear loads such as strip footings. Columns can also be arranged in a grid pattern to provide support to uniformly loaded structures such as ground ﬂoor slabs and embankments.
Soft to firm cohesive or loose to medium dense granular natural soils or made ground are displaced and densified using a vibrating poker with the installed stone column acting as a reinforcing element, improving the soil’s capability to carry a load, limit settlement and increase the rate of consolidation.
Vibro Stone Columns are a cost-effective process that is rapidly installed and generate negligible arisings. Follow on works can commence shortly after completion. VSC’s and other ground improvement techniques can be used in isolation or as part of a combination of foundation solutions. Both primary and recycled aggregates can be used to construct VSC’s.
Roger Bullivant Limited (RB) is one of the UK’s leading exponents of VSC’s and has over 25 years experience installing an array of ground improvement techniques in a range of ground conditions. RB’s fleet of low ground bearing VSC rigs allow thinner working platforms to be installed saving material costs and installation times.
Dynamic compaction is a ground improvement method that is used to increase the density of the in-situ soils and to improve the load bearing capacity of the ground. The process involves repeatedly dropping a heavy weight from a set height to achieve the required energy input.
The 12000 series NRG rigs are built in house by RB and allow a maximum drop weight of 12 tonne from 12 meters high. The weight lift and free fall cycle is leader guided; this being a critical safety feature as well as adding to drop precision and giving higher production rates than traditional crane bases systems. The 12000 series drop weights are interchangeable and special shaped weights can be used depending on the application and site specific ground conditions.
“GI – essential improvement of the bearing capabilities of the ground”