Keller Grundbau VC 131 Rüttelstopfverdichtung (3)

Vibro stone columns or aggregate piers are an array of

crushed stone Crushed stone or angular rock is a form of construction aggregate, typically produced by mining a suitable rock deposit and breaking the removed rock down to the desired size using crushers. It is distinct from naturally occurring gravel, which i ...

pillars placed with a vibrating tool into the soil below a proposed structure. This method of

ground improvement Ground may refer to: Geology * Land, the surface of the Earth not covered by water * Soil, a mixture of clay, sand and organic matter present on the surface of the Earth Electricity * Ground (electricity), the reference point in an electrical c ...

is also called vibro replacement. Such techniques increase the load

bearing capacity In geotechnical engineering, bearing capacity is the capacity of soil to support the loads applied to the ground. The bearing capacity of soil is the maximum average contact pressure between the foundation and the soil which should not produce she ...

and drainage of the soil while reducing

settlement Settlement may refer to: *Human settlement, a community where people live *Settlement (structural), the distortion or disruption of parts of a building * Closing (real estate), the final step in executing a real estate transaction *Settlement (fin ...

and

liquefaction In materials science, liquefaction is a process that generates a liquid from a solid or a gas or that generates a non-liquid phase which behaves in accordance with fluid dynamics. It occurs both naturally and artificially. As an example of the ...

potential. Stone columns are made across the area to be improved in a triangular or rectangular grid pattern. They have been used in Europe since the 1950s, and in the United States since the 1970s. Column depth depends on local soil strata, and usually penetrates weak soil. During construction, a vibrating tool suspended from a crane penetrates to the design depth by means of its own weight and vibrations. Predrilling may be required in dense soil or may be used to reduce the amount of ground displacement during installation. Crushed stone is introduced into the hole by one of two methods. In the dry bottom method, a pipe attached to the vibrator supplies stone directly to it. In the wet top method, water jets located in the vibrator's tip create an annular space around the vibrator through which stone is introduced from the top. The vibrating probe breaks down the pores of the surrounding soil, thereby densifying the soil. The stone that is poured in takes the place of the soil and keeps up the pressure on the soil that was created by the vibrating probe. The stone consists of crushed coarse aggregates of various sizes. The ratio in which the stones of different sizes will be mixed is decided by design criteria. Spacing and diameter of columns are also determined by design criteria.

References

Article at the Soil Liquefaction web site
of the

University of Washington The University of Washington (UW, simply Washington, or informally U-Dub) is a public research university in Seattle, Washington. Founded in 1861, Washington is one of the oldest universities on the West Coast; it was established in Seattle a ...

Vibro Replacement Stone Columns by Hayward Baker

Aggregate Piers / Vibro Stone Columns by Subsurface Constructors
{{Reflist Earthworks (engineering)