SOIL MASS STABILISATION USING JET GROUT TECHNIQUE-Paper

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The paper describes the design and use of jet grouting to improve ground conditions beneath foundations at a gas-turbine power plant. The site consists mainly of loose to medium-dense silty and fine sands, with groundwater only 1.5–2 m below ground level. Investigations included boreholes, cone penetration tests (CPTs), and geophysical studies. The groundwater was saline and contained high levels of sulphates and chlorides.<br /><br />The original soil bearing capacity was approximately 100 kPa, below the 150 kPa required for major structures. Settlement was the primary design concern: analyses of the untreated ground predicted 32.68 mm using PLAXIS 2D and 35.4 mm using Settle3D, exceeding the project limit of 25 mm. Liquefaction assessments indicated no significant liquefaction risk under the considered earthquake conditions.<br /><br />Jet grouting was selected after evaluating alternative ground-improvement and foundation methods. The design used 800 mm diameter, 9 m long columns arranged on a 2 m square grid, with a 1 m thick load-transfer platform above them. After modelling the improved ground, predicted settlements fell to 13.02 mm in PLAXIS 2D and 5.35 mm in Settle3D.<br /><br />The results showed that ground improvement was needed mainly to control settlement, rather than to address bearing capacity alone. The jet-grouted columns also increased the composite ground’s bearing capacity and stiffness. The power plant was commissioned in September 2021 and is operating at full capacity.

Keywords

jet grouting

ground improvement

settlement control

gas-turbine power plant

bearing capacity

silty sand

groundwater salinity

PLAXIS 2D

Settle3D

liquefaction assessment