Vacuum consolidation (or vacuum preloading) is a soft

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

improvement method that has been successfully used by

geotechnical engineers Geotechnical engineering, also known as geotechnics, is the branch of civil engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rock mechanics to solve its engineering problems. ...

and specialists of ground improvement companies in countries such as Australia, China, Korea, Thailand and France for soil improvement or

land reclamation Land reclamation, often known as reclamation, and also known as land fill (not to be confused with a waste landfill), is the process of creating new Terrestrial ecoregion, land from oceans, list of seas, seas, Stream bed, riverbeds or lake ...

. It does not necessarily require surcharge fill and vacuum loads of 80

kPa The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI ...

or greater can, typically, be maintained for as long as required. However, if loads of 80kPa or greater are needed in order to achieve the target soil improvement, additional surcharge may be placed on top of the vacuum system. The vacuum preloading method is cheaper and faster than the fill surcharge method for an equivalent load in suitable areas. Where the underlying ground consists of permeable materials, such as sand or sandy clay, the cost of the technique will be significantly increased due to the requirement of cut-off walls into non-permeable layers to seal off the vacuum. It has been suggested by Carter et al. (2005) that the settlement resulting from vacuum preloading is less than that from a surcharge load of the same magnitude as vacuum consolidation is influenced by drainage boundary conditions.

References

{{Geotechnical engineering Vacuum Soil improvers