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Cityview Place Holdings Pte Ltd is building a luxurious up market six storey condominium at Sentosa Cove, Singapore. The condominium comprises of two buildings built on raft foundation.
The soil on site is generally made up of 3m of loose sandfill followed by stiff clay of SPT-N values more than 50. However, at one location of the condominium, soft clay of up to 8m (SPT-N values less than 5) is present. The main contractor is concerned that the soft clay will pose settlement issues for the building.
Deep Soil Mixing (DSM) was proposed by Keller as a ground improvement solution at the location where soft clay is present. The ground improvement is designed such that the settlement from the building (loading up to 180kPa) is within tolerance.
The modified twin-shafts LRB155 capable of mixing two columns at the same time was mobilized to site. Deep Soil Mixing is performed to firm layer and the average column lengths are between 5m to 11m. An area of approximately 1,100m2 was improved. Coring samples show that the DSM columns are able to achieve Unconfined Compressive Strength (UCS) of average 3 MPa and modulus of 390MPa.
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