'Vibro-flotation' (vibro-compaction) is used to densify:
Choose the correct answer
Very soft cohesive clays (undrained shear < 30 kPa)
Loose granular sand deposits — vibration liquefies temporarily, grains rearrange to denser state
Rock masses
Organic and peaty soils
Correct Answer
B. Loose granular sand deposits — vibration liquefies temporarily, grains rearrange to denser state
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Vibro-compaction / vibroflotation: a vibrating probe (torpedo-shaped, 400 mm dia) penetrated into loose sand. Vibration (horizontal, 50 Hz) liquefies granular soil locally → sand grains rearrange under gravity to denser state. Sand backfill added from surface to fill voids. After withdrawal: stone column sometimes formed (vibro-replacement for cohesive soils). Suitable for: loose clean sand (< 15% fines).
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