By :Saravanan Panneervel 3606

Stone Column (IS:15284)

By :Saravanan Panneervel 3606

SCHOOL OF BUILDING SCIENCE AND TECHNOLOGYCEPT UNIVERSITY

There are diferrent techniques for application ofvibroflotation :

Vibro–compaction

Stone columns

Vibro-replacement Puprose: Stone columns are installed to reinforce

cohesive soils and to densify granular soils inorder to Increase bearing capacity Decrease total and differential settlement Provide vertical drainage pathways to increase the time-

rate of consolidation settlement Reduce the potential of liquefaction.

There are diferrent techniques for application ofvibroflotation :

Vibro–compaction

Stone columns

Vibro-replacement Puprose: Stone columns are installed to reinforce

cohesive soils and to densify granular soils inorder to Increase bearing capacity Decrease total and differential settlement Provide vertical drainage pathways to increase the time-

rate of consolidation settlement Reduce the potential of liquefaction.

Stone columns are categorized on the basis ofmethod of construction :

Dry Top feed system

Dry Bottom feed system

Wet Top feed system

Types Of Stone Column Stone columns are categorized on the basis of

method of construction :

Dry Top feed system

Dry Bottom feed system

Wet Top feed system

Method of Construction Holes are bored as per design by help of auger or vibrating unit

as per design and desired diameter Depending on type of existing soil

suitable method is adopted .

Holes are bored as per design by help of auger or vibrating unitas per design and desired diameter

Depending on type of existing soilsuitable method is adopted .

Vibroflot (vibrating unit)Length = 2 – 3 mDiameter = 0.3 – 0.5 mMass = 2 tonnes

(lowered into the ground andvibrated)

The vibratory probe is either fully or partially removed from thehole depending on the ground conditions and stone is dumpedinto the hole.

The stone is placed in 0.6m to 1m lifts, and the probe is re-inserted following placement of each lift to compact the stoneandforce the stone into the surrounding formation.

Loaders with side-dumping buckets are preferred as The probe is held in place once it has penetrated the previous lift

of stone until the specified resistance criteria is met.

Dry Top Feed Method The vibratory probe is either fully or partially removed from the

hole depending on the ground conditions and stone is dumpedinto the hole.

The stone is placed in 0.6m to 1m lifts, and the probe is re-inserted following placement of each lift to compact the stoneandforce the stone into the surrounding formation.

Loaders with side-dumping buckets are preferred as The probe is held in place once it has penetrated the previous lift

of stone until the specified resistance criteria is met.

Dry Top Feed Method Sequence

In settings where the hole collapses or partially collapses whenthe vibratory probe is retracted, it is not possible to constructhigh quality, continuous, stone columns using the dry top-feedmethod.

The bottom-feed method incorporates a tremie pipe that ismounted to the side of the probe to allow stone to be introducedat the bottom of the hole without fully retracting the probe.

Dry Bottom Feed Method

In settings where the hole collapses or partially collapses whenthe vibratory probe is retracted, it is not possible to constructhigh quality, continuous, stone columns using the dry top-feedmethod.

The bottom-feed method incorporates a tremie pipe that ismounted to the side of the probe to allow stone to be introducedat the bottom of the hole without fully retracting the probe.

Dry Bottom Feed Method sequence

Wet Top Feed Method The wet top-feed method of stone column installation involves

jetting water as the probe penetrates to full depth, reducing thewater flow, and placing the stone .

The stone column is constructed using techniques similar to thedry top-feed method, except that a flow water is maintained in thehole during stone placement.

The wet top-feed method is employed in weak, unstable soils tomaintain a stable hole, to increase the diameter of the stonecolumns, and to remove fine materials (clay, silt, and organicparticles) from the hole.

The wet top-feed method of stone column installation involvesjetting water as the probe penetrates to full depth, reducing thewater flow, and placing the stone .

The stone column is constructed using techniques similar to thedry top-feed method, except that a flow water is maintained in thehole during stone placement.

The wet top-feed method is employed in weak, unstable soils tomaintain a stable hole, to increase the diameter of the stonecolumns, and to remove fine materials (clay, silt, and organicparticles) from the hole.

Water

Probe

Design (as per case study)

Plan

Zig ZagArrangement

Section

Zig ZagArrangement

Zig zag arrangement is provided to cover more area forstrengthening

StoneColumn

1 m

Zig zag arrangement is provided to cover more area forstrengthening

The screenshot softwareplaxis show showingpossible slope failurewithout stone columns.

After slope stabilisationwith stone columns

Thank You

References: “Stone Columns for Industrial Fills” - By Martin G. Taube, P.E., P.G. and

John R. Herridge ,Nicholson Construction Company, Cuddy, Pennsylvania “COMPACTION “– By N. Sivakugan http://www.vibroflotation.com/Vibro/vibroflotation_fr.nsf/site/Stone-

Columns.Dry-Stone-Columns http://www.haywardbaker.com Project Training Data

References: “Stone Columns for Industrial Fills” - By Martin G. Taube, P.E., P.G. and

John R. Herridge ,Nicholson Construction Company, Cuddy, Pennsylvania “COMPACTION “– By N. Sivakugan http://www.vibroflotation.com/Vibro/vibroflotation_fr.nsf/site/Stone-

Columns.Dry-Stone-Columns http://www.haywardbaker.com Project Training Data