ground improvement technique
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04-04-2011, 02:10 PM
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What is ground improvement technique?
Ground improvement technique is the process of improving the geo-technical characteristics of soil used in construction
TYPES OF GROUND IMPROVEMENT TECHNIQUES
Grouting is a process where by fluid like material, either in suspension or in solution form are injected into subsurface soil or rock to achieve a decrease in permeability and compressibility AIMS OF GROUTING
To decrease the permeability.
To increase the shear strength.
To decrease the compressibility
GROUT PROVES MORE EFFECTIVE IN THE FOLLOWING CASES
When the foundation has to be constructed below ground water table.
When there is difficult to the foundation level (ex: city work, tunnel shafts,sewers, subway construction).
When the geometric dimensions of the foundations are complicated and involved many boundaries and contact zones.
When the adjacent structure require that the soil of the foundation strata should not be excavated
CLASSIFICATION OF GROUT MATERIALS
These consists of emulsion of colloidal droplets of liquid in a dispersed phase.
Ex: Bitumen, foams created by emulsifying a gas into cement etc.
TYPES OF GROUTING
The ASCE Geotechnical Engineering Division Committee on grouting defined Jet grouting as a “technique utilizing a special drill bit with horizontal and vertical high speed water jets to excavate alluvial soils and produce hard impervious column by pumping grout through the horizontal nozzles that jets and mixes with foundation material as the drill bit is with drawn”.
Nearly all soil types grout able
Designable strength & permeability
No harmful vibrations
Can be performed in limited workspace
Safest method of under pinning construction
Much faster than alternative method
Monitoring the grout taken as a function of pressure
Observing ground heave
Digging inspection pits
Retrieving Core samples for examination and laboratory testing
Conducting borehole permeability tests.