Sand Drain on Land (Land SD) Method

Improvement Principle Compaction, Consolidation and Reinforcement
A method to facilitate the consolidation by attempting to shorten the drainage distance through the installation of numerous vertical sand piles, which the casing pipe is driven into the soft cohesive ground, and to discharge the sand inside while withdrawing the casing. Land SD Method is one of the most typical vertical drain method where it is widely used together with surcharge method.
 SD-land-flow
Advantages Construction cost is comparatively cheaper than other method.
Drain diameter is big, hence lesser late consolidation.
Big capacity vibro-hammer is used, hence the penetration capacity
is great.
Due to big construction machine, hence great construction is possible.
Disadvantages Need for consolidation untouched period until settelment coverage.
Vibration & noise is big
Construction machine is big, hence separate measures are necessary for very soft ground.
Applicable Ground Cohesive soil, and organic soil.
Objectives Promote settlement on reclaimed land and backfill.
Improvement Effectiveness Sandy Soil Promote consolidation
Increase shear strength
Cohesive Soil Not Applicable
Specification Standard Pile Diameter Ø 400mm , Ø 500mm
Pile Arrangement
Square , Triangle ,  Rectangle
Pile Spacing 1.5m ~ 3.5m
Penetration Depth Max GL -40m
Penetration Strength Max N-value < 20
Material Sand
Environment Vibration Big
Noise Big
Ground Displacement Small ( Except the displacement by consolidation settlement )