deep compaction

DEEP COMPACTIONDEEP COMPACTION

THE MAIN PURPOSE OF TREATING OR IMPROVING THE THE MAIN PURPOSE OF TREATING OR IMPROVING THE SOILS IS TO ELIMINATE THE DANGER OF EXCESSIVE SOILS IS TO ELIMINATE THE DANGER OF EXCESSIVE SETTLEMENTS. LOOSE COHESIONLESS SOILS GENERALLY SETTLEMENTS. LOOSE COHESIONLESS SOILS GENERALLY DO NOT POSE SERIOUS PROBLEMS IN TERMS OF STABILITY DO NOT POSE SERIOUS PROBLEMS IN TERMS OF STABILITY AND SETTLEMENT. LIQUEFACTION IS THE MAIN CONCERN AND SETTLEMENT. LIQUEFACTION IS THE MAIN CONCERN FOR LOOSE COHESIONLESS SOILS UNDER WATER TABLE. FOR LOOSE COHESIONLESS SOILS UNDER WATER TABLE. OTHER DYNAMIC LOADS ALSO AFFECT THESE SOILS.OTHER DYNAMIC LOADS ALSO AFFECT THESE SOILS.

METHODS FOR COHESIONLESS SOILS : METHODS FOR COHESIONLESS SOILS :

- VIBROCOMPACTION TECHNIQUES- VIBROCOMPACTION TECHNIQUES- COMPACTION PILES- COMPACTION PILES

- BLASTING- BLASTING

CE-464 Ground ImprovementCE-464 Ground Improvement

1. VIBROFLOATATION1. VIBROFLOATATION

THIS IS NOT A NEW METHOD. (50 YEARS OLD). THE THIS IS NOT A NEW METHOD. (50 YEARS OLD). THE EQUIPMENT HAS THREE ELEMENTS.EQUIPMENT HAS THREE ELEMENTS.

A) THE VIBRATOR OR VIBROFLOT A) THE VIBRATOR OR VIBROFLOT

B) EXTENSION TUBES B) EXTENSION TUBES

C) CRANE (-T-WATER JET SUPPLY WATER, PUMP+GENERATOR, C) CRANE (-T-WATER JET SUPPLY WATER, PUMP+GENERATOR, CABLES).CABLES).

VIBROFLOT IS A CYLINDRICAL PROBE WHICH PENETRATES VIBROFLOT IS A CYLINDRICAL PROBE WHICH PENETRATES INTO THE GROUND WITH THE AID OF VIBRATION (VERTICAL INTO THE GROUND WITH THE AID OF VIBRATION (VERTICAL AND/OR HORIZONTAL) AND ITS OWN WEIGHT AND JETTING AND/OR HORIZONTAL) AND ITS OWN WEIGHT AND JETTING (WATER MOSTLY, FOR DEEP PENETRATIONS AIR OR AIR (WATER MOSTLY, FOR DEEP PENETRATIONS AIR OR AIR AND WATER).AND WATER).


VIBROFLOT DIAMETERS ARE IN THE RANGE OF 0.35 - 0.50 m, VIBROFLOT DIAMETERS ARE IN THE RANGE OF 0.35 - 0.50 m,

LENGTHS 2-6 m. AN ECCENTRIC MASS IS AT THE LOWER LENGTHS 2-6 m. AN ECCENTRIC MASS IS AT THE LOWER

PART OF THE VIBRO PROBE WHICH IS A HOLLOW STEEL PART OF THE VIBRO PROBE WHICH IS A HOLLOW STEEL

TUBE WEIGHTS OF VIBROFLOTS ARE USUALLY IN THE TUBE WEIGHTS OF VIBROFLOTS ARE USUALLY IN THE

RANGE OF 20 - 40 kN (2-4 ton) AND THEY DEVELOP RANGE OF 20 - 40 kN (2-4 ton) AND THEY DEVELOP

HORIZONTAL CENTRIFUGAL FORCES OF 80-160 kN. HORIZONTAL CENTRIFUGAL FORCES OF 80-160 kN.

VIBRATION AMPLITUDES ARE UP TO 20-25 mm AND USUAL VIBRATION AMPLITUDES ARE UP TO 20-25 mm AND USUAL

OPERATING FREQUENCIES ARE 30-50 Hz (1800 - 3000 rpm) OPERATING FREQUENCIES ARE 30-50 Hz (1800 - 3000 rpm)

(35-100 kW POWER) WATER JETS MAY BE APPLIED AT TOP (35-100 kW POWER) WATER JETS MAY BE APPLIED AT TOP

AND/OR BOTTOM.AND/OR BOTTOM.


TYPICAL VIBROFLOT PENETRATION RATES: 1-2 m/mIn, TYPICAL VIBROFLOT PENETRATION RATES: 1-2 m/mIn,

VIBROFLOT WITHDRAWAL / COMPACTION RATES : 0.3 m/mIn. VIBROFLOT WITHDRAWAL / COMPACTION RATES : 0.3 m/mIn.

WATER JETTING PRESSURES UP TO 800 kN/mWATER JETTING PRESSURES UP TO 800 kN/m22, FLOW RATES , FLOW RATES

UP TO 3000 lt/mIn (50 lt/sec). SAND BACKFILL IS SUPPLIED AT UP TO 3000 lt/mIn (50 lt/sec). SAND BACKFILL IS SUPPLIED AT

A RATE UP TO 1.5 mA RATE UP TO 1.5 m33/m RADIUS OF INFLUENCE, R FROM THE /m RADIUS OF INFLUENCE, R FROM THE

VIBRATOR DEPENDS ON THE TYPE OF VIBRATOR AND SOIL VIBRATOR DEPENDS ON THE TYPE OF VIBRATOR AND SOIL

TYPE 0.6–0.9 m FOR 20 % OR MORE SMALLER THAN NO. 200 TYPE 0.6–0.9 m FOR 20 % OR MORE SMALLER THAN NO. 200

SIEVE AND 2 m FOR CLEAN SANDS.SIEVE AND 2 m FOR CLEAN SANDS.


MOST EFFECTIVE IN CLEAN SANDS, HOWEVER WEBB & MOST EFFECTIVE IN CLEAN SANDS, HOWEVER WEBB & HALL (1968) REPORT GOOD SUCCESS IN SOILS CONTAINING HALL (1968) REPORT GOOD SUCCESS IN SOILS CONTAINING APPRECIABLE PORTIONS OF SILT AND CLAY AS MUCH AS APPRECIABLE PORTIONS OF SILT AND CLAY AS MUCH AS 30%. CAQUAT - KERISEL (1966) RECOMMEND COARSE SAND, 30%. CAQUAT - KERISEL (1966) RECOMMEND COARSE SAND, GRAVEL OR COBBLES AS FILLING MATERIAL. WHEN GRAVEL OR COBBLES AS FILLING MATERIAL. WHEN DENSIFYING FINE SANDS AND SILTY SAND COARSE DENSIFYING FINE SANDS AND SILTY SAND COARSE PARTICLES ARE MORE EFFECTIVE TO IMPROVE PARTICLES ARE MORE EFFECTIVE TO IMPROVE TRANSMISSION OF VIBRATION TO SURROUNDING SOIL TRANSMISSION OF VIBRATION TO SURROUNDING SOIL BETTER.BETTER.

THERE ARE ALSO CASES ON RECORD WITH VERY FINE THERE ARE ALSO CASES ON RECORD WITH VERY FINE SAND, FINE SAND WITH LENSES OF MUD, FINE SAND WITH SAND, FINE SAND WITH LENSES OF MUD, FINE SAND WITH BALLS OF CLAY AND SILTS AND SANDS WITH CLAY LAYERS BALLS OF CLAY AND SILTS AND SANDS WITH CLAY LAYERS UP TO A METER.UP TO A METER.


RELATIVE DENSITY, Dr,OF AT LEAST 70 % CAN BE OBTAINED RELATIVE DENSITY, Dr,OF AT LEAST 70 % CAN BE OBTAINED BETWEEN CENTERS. INCREASE IN RELATIVE DENSITY IS BETWEEN CENTERS. INCREASE IN RELATIVE DENSITY IS BETWEEN 20% - 40%.BETWEEN 20% - 40%.

qall AFTER TREATMENT IS USUALLY AROUND 2 - 3 kg/cmqall AFTER TREATMENT IS USUALLY AROUND 2 - 3 kg/cm22 (COST ROUGHLY 2- 4 $/m(COST ROUGHLY 2- 4 $/m33 USA RATE). USA RATE).

THE DESIGN OF A VIBROFLOATATION TREATMENT THE DESIGN OF A VIBROFLOATATION TREATMENT

REQUIRES SPECIFICATION OF THE DESIRED RELATIVE REQUIRES SPECIFICATION OF THE DESIRED RELATIVE

DENSITY AND THE PATTERN AND SPACING OF VIBROFLOT DENSITY AND THE PATTERN AND SPACING OF VIBROFLOT

HOLES. A RELATIVE DENSITY OF AT LEAST 75 % HAS BEEN HOLES. A RELATIVE DENSITY OF AT LEAST 75 % HAS BEEN

A FREQUENTLY USED REQUIREMENT TO INSURE AGAINST A FREQUENTLY USED REQUIREMENT TO INSURE AGAINST

EXCESSIVE SETTLEMENT OR LIQUEFACTION, HOWEVER THE EXCESSIVE SETTLEMENT OR LIQUEFACTION, HOWEVER THE

VALUE SPECIFIED IS A FUNCTION OF THE TYPE OF PROJECT VALUE SPECIFIED IS A FUNCTION OF THE TYPE OF PROJECT

AND THE LOCAL CONDITIONS.AND THE LOCAL CONDITIONS.


D'APPOLONIA, MILLER AND WARE (1955) SUMMARIZE SOME OFD'APPOLONIA, MILLER AND WARE (1955) SUMMARIZE SOME OFTHEIR FINDINGS;THEIR FINDINGS;

TRIANGULAR PATTERN PREFERRED DUE TO GREATEST TRIANGULAR PATTERN PREFERRED DUE TO GREATEST COMPACTION EFFORT OVERLAP.COMPACTION EFFORT OVERLAP.

D, IS NOT INCREASED ABOVE 70% AT POINTS MORE THAN 1 D, IS NOT INCREASED ABOVE 70% AT POINTS MORE THAN 1 m FROM A SINGLE VIBROFLOT COMPACTION.m FROM A SINGLE VIBROFLOT COMPACTION.

THE OVERLAPPING EFFECT FOR SPACINGS GREATER THAN THE OVERLAPPING EFFECT FOR SPACINGS GREATER THAN 2.4 m IS SMALL.2.4 m IS SMALL.

SPACINGS LESS THAN 1.8 m SHOULD GIVE Dr HIGHER THAN SPACINGS LESS THAN 1.8 m SHOULD GIVE Dr HIGHER THAN 70 % WITHIN THE COMPACTED AREA.70 % WITHIN THE COMPACTED AREA.

THE EFFECT OF ADJACENT COMPACTIONS CAN BE THE EFFECT OF ADJACENT COMPACTIONS CAN BE SUPERIMPOSED.SUPERIMPOSED.

THERE ARE PROCEDURES FOR DETERMINING VIBROFLOT THERE ARE PROCEDURES FOR DETERMINING VIBROFLOT SPACING REQUIRED TO OBTAIN A SPECIFIED Dr (mIn.) .SPACING REQUIRED TO OBTAIN A SPECIFIED Dr (mIn.) .


WEBB & HALL (1968) ALSO DESCRIBE A METHOD FOR SILTY WEBB & HALL (1968) ALSO DESCRIBE A METHOD FOR SILTY

AND CLAYEY SAND.AND CLAYEY SAND.

A SPACING OF 2.1 – 2.4 m IS OFTEN CHOSEN. CLEAN A SPACING OF 2.1 – 2.4 m IS OFTEN CHOSEN. CLEAN

COARSE SANDS AND COARSER SOILS MAY REQUIRE 2.4 m COARSE SANDS AND COARSER SOILS MAY REQUIRE 2.4 m

OR MORE. FINER MATERIAL AND MATERIAL CONTAINING OR MORE. FINER MATERIAL AND MATERIAL CONTAINING

CLAY INCLUSIONS MAY REQUIRE MUCH CLOSER SPACINGS.CLAY INCLUSIONS MAY REQUIRE MUCH CLOSER SPACINGS.

RANGE (1.5 -3M) DEPENDS ON; RANGE (1.5 -3M) DEPENDS ON;

- TYPE OF SOIL AND BACKFILL- TYPE OF SOIL AND BACKFILL

- PROBE TYPE AND ENERGY- PROBE TYPE AND ENERGY

- LEVEL OF IMPROVEMENT REQUIRED- LEVEL OF IMPROVEMENT REQUIREDCE-464 Ground ImprovementCE-464 Ground Improvement

2. VIBRATING PROBES2. VIBRATING PROBES

VIBRATORY PIPES OR PROBES MAY BE PUSHED INTO THE SOILVIBRATORY PIPES OR PROBES MAY BE PUSHED INTO THE SOIL

TO DENSIFY THE SOIL LAYERS WITHOUT ADDING MATERIAL ATTO DENSIFY THE SOIL LAYERS WITHOUT ADDING MATERIAL AT

DEPTH, ONLY SURFACE ADDITION IS DONE.DEPTH, ONLY SURFACE ADDITION IS DONE.

ANDERSON(1974) USES PILE VIBRO-DRIVER HAMMER ON TOPANDERSON(1974) USES PILE VIBRO-DRIVER HAMMER ON TOP

OF A 0.76 m DIAMETER PIPE PILE (3-5 m LONGER THAN THEOF A 0.76 m DIAMETER PIPE PILE (3-5 m LONGER THAN THE

DEPTH OF TREATMENT). TYPICAL APPLICATIONDEPTH OF TREATMENT). TYPICAL APPLICATION

CHARACTERISTICS ARE; FREQUENCY 15 Hz, VERTICALCHARACTERISTICS ARE; FREQUENCY 15 Hz, VERTICAL

AMPLITUDE 10-25 mm, APPROXIMATELY 15 Probes /hr, 1-3 mAMPLITUDE 10-25 mm, APPROXIMATELY 15 Probes /hr, 1-3 m

SPACING, UPPER FEW METERS ARE NOT EFFECTIVELYSPACING, UPPER FEW METERS ARE NOT EFFECTIVELY

DENSIFIED.DENSIFIED.

SAITO (1977) USES AGAIN VIBRATORY PILE DRIVING HAMMERSAITO (1977) USES AGAIN VIBRATORY PILE DRIVING HAMMER

AND VIBRO-RODSAND VIBRO-RODSCE-464 Ground ImprovementCE-464 Ground Improvement

3. 3. VIBRO - COMPOZER METHODVIBRO - COMPOZER METHOD

COMPRESSED COMPRESSED

AIR IS USED AIR IS USED

INSIDE THE INSIDE THE

CASING TO CASING TO

HOLD SANDHOLD SAND IN IN

PLACE WHILE PLACE WHILE

WWITHDRAWINGITHDRAWING

THE CASING THE CASING

MURAYAMAMURAYAMA

(1958)(1958)


4.4. SOIL VIBRATORY STABILIZING METHOD SOIL VIBRATORY STABILIZING METHOD (SVS)(SVS)

IN SVS VERTICAL VIBRATION AND HORIZONTAL VIBRATION IN SVS VERTICAL VIBRATION AND HORIZONTAL VIBRATION

ARE APPLIED. SIMILAR TO VIBROFLOT SAND BACKFILL ARE APPLIED. SIMILAR TO VIBROFLOT SAND BACKFILL

USED, WATER IS NOT USEDUSED, WATER IS NOT USED..


5.5. COMPACTION PILESCOMPACTION PILES

DENSIFICATION FROM TWO EFFECTS DENSIFICATION FROM TWO EFFECTS

1.1. DISPLACEMENT OF SOILDISPLACEMENT OF SOIL

2.2. VIBRATION DURING DRIVINGVIBRATION DURING DRIVING

A CASING WITH DETACHABLE (LOST POINT) END PLATE A CASING WITH DETACHABLE (LOST POINT) END PLATE

OR WITH A SPECIAL OPENING MECHANISM AT THE TIP IS OR WITH A SPECIAL OPENING MECHANISM AT THE TIP IS

DRIVEN BACKFILL IS FILLED AS THE CASING IS DRIVEN BACKFILL IS FILLED AS THE CASING IS

WITHDRAWN. USUALLY 0.9 - 1.5M SPACING IS USED. WITHDRAWN. USUALLY 0.9 - 1.5M SPACING IS USED.

BETTER IN FULLY SATURATED OR DRY SANDS.BETTER IN FULLY SATURATED OR DRY SANDS.


FRANKI MACHINES AND TECHNIQUE ARE ALSO FRANKI MACHINES AND TECHNIQUE ARE ALSO VERY VERY

SUITABLE TO FORM SAND OR GRAVEL PILES.SUITABLE TO FORM SAND OR GRAVEL PILES.

IF THE PERMEABILITY OF THE SOIL IS NOT HIGH, SAND OR IF THE PERMEABILITY OF THE SOIL IS NOT HIGH, SAND OR

GRAVEL PILES ALSO ACT AS DRAINAGE COLUMNSGRAVEL PILES ALSO ACT AS DRAINAGE COLUMNS

SAND DRAINS TO ACCELERATE SETTLEMENTS ARE SAND DRAINS TO ACCELERATE SETTLEMENTS ARE

DIFFERENT CONCEPT AS WE HAVE DISCUSSED PREVIOUSLYDIFFERENT CONCEPT AS WE HAVE DISCUSSED PREVIOUSLY

HORIZONTAL EXTENT OF THE COMPACTED ZONE ALONG HORIZONTAL EXTENT OF THE COMPACTED ZONE ALONG

THE SHAFT IS ABOUT 5 RADII. FRANKI TECHNIQUE IS MORE THE SHAFT IS ABOUT 5 RADII. FRANKI TECHNIQUE IS MORE

EFFECTIVE THAN A DEFFECTIVE THAN A DRIRIVEN PIPE, MEYERHOF (1959).VEN PIPE, MEYERHOF (1959).


SUITABILITY OF SOILS AND METHODSSUITABILITY OF SOILS AND METHODS

SOIL TYPE, GRADATION, FINES CONTENT ETC.SOIL TYPE, GRADATION, FINES CONTENT ETC.

DEGREE OF SATURATION, LEVEL OF G.W.TDEGREE OF SATURATION, LEVEL OF G.W.T

INITIAL DRINITIAL DR

’’VV00 , , ’’H0H0 (OCR, (OCR, VMAXVMAX))

INITIAL SOIL STRUCTURE, CEMENTATION, AGE ETC.INITIAL SOIL STRUCTURE, CEMENTATION, AGE ETC.

SPECIAL CHARACTERISTICS OF THE METHOD USEDSPECIAL CHARACTERISTICS OF THE METHOD USED

VIBROCOMPACTION METHODS ARE BEST SUITED TO VIBROCOMPACTION METHODS ARE BEST SUITED TO

CLEAN COHESIONLESS SOILS WITH 20-CLEAN COHESIONLESS SOILS WITH 20-225% MAXIMUM FINE 5% MAXIMUM FINE

CONTENT DUE TO LOW PERMEABILITY AND COHESIONCONTENT DUE TO LOW PERMEABILITY AND COHESION

IN LOESS, SILTY SANDS WHERE FINES ARE HIGH IN %IN LOESS, SILTY SANDS WHERE FINES ARE HIGH IN %,,

TRY OTHER TECHNIQUES LIKE HEAVYTRY OTHER TECHNIQUES LIKE HEAVY T TAMPING (DYNAMIC AMPING (DYNAMIC

CONSOLIDATION)CONSOLIDATION)CE-464 Ground ImprovementCE-464 Ground Improvement

EVALUATION OF THE TREATED GROUND MAY BE DONE BY EVALUATION OF THE TREATED GROUND MAY BE DONE BY

ONE OR TWO OF THE FOLLOWING METHODS;ONE OR TWO OF THE FOLLOWING METHODS;

1.1. SURFACE SETTLEMENT MARKERSSURFACE SETTLEMENT MARKERS

2.2. VOLUME OF ADDED SOIL (CRATERS OR VOLUME OF ADDED SOIL (CRATERS OR

VIBROCOMPACTION DISP.)VIBROCOMPACTION DISP.)

3.3. STANDARD PENERATION TEST, SPT.STANDARD PENERATION TEST, SPT.

4.4. CONE PENETRATION TEST, DUTCH CONE, CPTCONE PENETRATION TEST, DUTCH CONE, CPT

5.5. PRESSUREMETER TEST, PMTPRESSUREMETER TEST, PMT

6.6. SEISMIC SHEAR WAVE VELOCITY DETERMINATIONS, VSSEISMIC SHEAR WAVE VELOCITY DETERMINATIONS, VS

7.7. PILE DRIVING RESISTANCESPILE DRIVING RESISTANCES

8.8. PLATE LOADING TESTSPLATE LOADING TESTS

9.9. DOWN - HOLE DENSITY METERS.DOWN - HOLE DENSITY METERS.CE-464 Ground ImprovementCE-464 Ground Improvement

VERYLOOSE

LOOSEMEDIUMDENSE

DENSEVERY

DENSE

SPT- NVALUE <4 4-10 10-30 30-35 >50

CPT QC

(KG/CM2)<50 50-100 >200

EQUIVALENTDR (%) <15 15-35 35-65 65-85 85-100

DRY UNITWEIGHT(KN/M3)

<14 14-16 16-18 18-20 >20

FRICTIONANGLE <30 30-32 32-35 35-38 >38


VIBROCOMPACTION GRIDS ARE SQUARE OR TRIANGULAR VIBROCOMPACTION GRIDS ARE SQUARE OR TRIANGULAR ASSUMING DENSIFICATION ONLY IN LATERAL DIRECTION ASSUMING DENSIFICATION ONLY IN LATERAL DIRECTION (D<80CM)(D<80CM)

SQUARESQUARE TRIANGULARTRIANGULAR(CONSIDER AVERAGE (CONSIDER AVERAGE e)e)


dee

eS

0

0 )1(d

ee

eS

0

0 )1(08.1

BROWN (1977) HAS DEFINED A SUITABILITY NUMBER FOR BROWN (1977) HAS DEFINED A SUITABILITY NUMBER FOR VIBROFLOATATION BACKFILLSVIBROFLOATATION BACKFILLS..

DD1010, D, D2020 and D and D5050 ARE MM PARTICLE SIZES CORRESPONDING % PASSING. ARE MM PARTICLE SIZES CORRESPONDING % PASSING.

SUITABILITY NUMBERS AND BACKFILL CLASSESSUITABILITY NUMBERS AND BACKFILL CLASSES

FASTER THE VIBROFLOT TAKEN UP

0-10 EXCELLENT

10-20 GOOD

20-30 FAIR

30-50 POOR

> 50 UNSUITABLECE-464 Ground ImprovementCE-464 Ground Improvement

210

220

250 )(

1

)(

1

)(

37.1

DDDNumberySuitabilit

DYNAMIC CONSOLIDATION OR DYNAMIC CONSOLIDATION OR HEAVY TAMPING (POUNDING)HEAVY TAMPING (POUNDING)

FIRST APPLICATIONS 1970 - 1973 BY MENARDFIRST APPLICATIONS 1970 - 1973 BY MENARD..

IT IS REPEATED DROPPING OF A HEAVY WEIGHT ON TO THEIT IS REPEATED DROPPING OF A HEAVY WEIGHT ON TO THE

SURFACE OF THE SOIL TO COMPACT IT.SURFACE OF THE SOIL TO COMPACT IT.

WEIGHTS (OR POUNDERS) USED MAY BE CONCRETE BLOCKS,WEIGHTS (OR POUNDERS) USED MAY BE CONCRETE BLOCKS,

TOUGHENED STEEL PLATES BOLTED TOGETHER OR THICK STEELTOUGHENED STEEL PLATES BOLTED TOGETHER OR THICK STEEL

SHELLSSHELLS FILLED WITH CONCRETE OR SAND AND MAY RANGEFILLED WITH CONCRETE OR SAND AND MAY RANGE

BETWEEN 1/2 - 200 TONS.BETWEEN 1/2 - 200 TONS.

DURABILITY OF THE WEIGHT ISDURABILITY OF THE WEIGHT IS IMPORANT BECAUSE OF LARGE IMPORANT BECAUSE OF LARGE

NUMBER OFNUMBER OF DROPS.DROPS.

DROP HEIGHTS (H) ARE UP TO 40 M AND SQUARE OR CIRCULARDROP HEIGHTS (H) ARE UP TO 40 M AND SQUARE OR CIRCULAR

SHAPES IN PLAN ARE USED.SHAPES IN PLAN ARE USED.CE-464 Ground ImprovementCE-464 Ground Improvement

B(WIDTH) OR D (DIAMETER) IS FEW METERS AND DEPENDS ONB(WIDTH) OR D (DIAMETER) IS FEW METERS AND DEPENDS ON

WEIGHT REQUIREDWEIGHT REQUIRED

MATERIALMATERIAL

BEARING CAPACITY OF THE SOILBEARING CAPACITY OF THE SOIL

A TYPICAL APPLICATION H = 20 M AND W = 15 - 20 TON A TYPICAL APPLICATION H = 20 M AND W = 15 - 20 TON DEPTH OF COMPACTION = 10 MDEPTH OF COMPACTION = 10 M..

USUALLY LARGE AREAS (NOT VERY CLOSE TO POPULATED USUALLY LARGE AREAS (NOT VERY CLOSE TO POPULATED AREAS) ARE SELECTED TO APPLY HIS METHOD.AREAS) ARE SELECTED TO APPLY HIS METHOD.

USUALLY RECTANGULAR GRID POINTS 5-10 M APART ARE USUALLY RECTANGULAR GRID POINTS 5-10 M APART ARE USED, 5-10 BLOWS OF THE TAMPER ARE APPLIED AT EACH USED, 5-10 BLOWS OF THE TAMPER ARE APPLIED AT EACH POINT.POINT.

THE NUMBER OF BLOWS AT A POINT IS CONTROLLED THE NUMBER OF BLOWS AT A POINT IS CONTROLLED PRIMARILY BY THE OBSERVATION OF THE DEPTH OF PRIMARILY BY THE OBSERVATION OF THE DEPTH OF DEPRESSION CREATED.DEPRESSION CREATED.


A TYPICAL TREATMENT : AVERAGE 2-3 BLOWS /A TYPICAL TREATMENT : AVERAGE 2-3 BLOWS /mm22

2 OR 3 COVERAGES OF AN AREA MAY BE REQUIRED. THE TIME 2 OR 3 COVERAGES OF AN AREA MAY BE REQUIRED. THE TIME

INTERVAL BETWEEN COVERAGES DEPENDS ON THE RATE OF INTERVAL BETWEEN COVERAGES DEPENDS ON THE RATE OF

DISSIPATION OF EXCESS POREWATER PRESSURES AND DISSIPATION OF EXCESS POREWATER PRESSURES AND

STRENGTH REGAIN.STRENGTH REGAIN.

EXAMPLE FOR COARSE SAND DAYS AND FOR FINE GRAINED SOIL EXAMPLE FOR COARSE SAND DAYS AND FOR FINE GRAINED SOIL

WEEKS MAY BE NECESSARY.WEEKS MAY BE NECESSARY.

GROUND SURFACE IS USUALLY LEVELLED BETWEEN GROUND SURFACE IS USUALLY LEVELLED BETWEEN

COVERAGES BY IMPORTED GRANULAR MATERIAL.COVERAGES BY IMPORTED GRANULAR MATERIAL.

BEFORE FURTHER PASSES OF TAMPING, MEASUREMENTS ARE BEFORE FURTHER PASSES OF TAMPING, MEASUREMENTS ARE

DONE AFTER LEVELLING TO ASSESS AVERAGE FORCED DONE AFTER LEVELLING TO ASSESS AVERAGE FORCED

SETTLEMENT ( DS : 2 - 5 % PER COVERAGE)SETTLEMENT ( DS : 2 - 5 % PER COVERAGE)..

TO ASSESS THE TRUE VOLUME COMPRESSION MEASUREMENTS TO ASSESS THE TRUE VOLUME COMPRESSION MEASUREMENTS

AND CALCULATIONS ARE DONE AT SELECTED POINTSAND CALCULATIONS ARE DONE AT SELECTED POINTS..


BEFORE STARTING TAMPING A SURFACE BLANKET OF BEFORE STARTING TAMPING A SURFACE BLANKET OF

UNSATURATED GRANULAR MATERIAL I M THICK OR MORE UNSATURATED GRANULAR MATERIAL I M THICK OR MORE

IS SPREAD OVER THE AREA TO BE TAMPED IF THIS DOES IS SPREAD OVER THE AREA TO BE TAMPED IF THIS DOES

NOT OCCUR NATURALLY TO LESSEN LOCAL SHEAR & TO NOT OCCUR NATURALLY TO LESSEN LOCAL SHEAR & TO

ALLOW EFFECTIVE COMPACTION.ALLOW EFFECTIVE COMPACTION.

"IRONING" IS FULL COVERAGE OF THE AREA BY SMALL "IRONING" IS FULL COVERAGE OF THE AREA BY SMALL

IMPACTS. IT COMPACTS THEIMPACTS. IT COMPACTS THE SURFACE LAYERS (H = 2-3 M). SURFACE LAYERS (H = 2-3 M).

IT CAN BE DONE BY SURFACE ROLLING.IT CAN BE DONE BY SURFACE ROLLING.


ECONOMIC DEPTH BELOW BLANKET: 3-10 M.ECONOMIC DEPTH BELOW BLANKET: 3-10 M.

S(NO IMPROVEMENT) / S(AFTER TAMPING) = 4-5S(NO IMPROVEMENT) / S(AFTER TAMPING) = 4-5

NOTE THAT IMPROVEMENT IS NOT UNIFORM WITH DEPTH.NOTE THAT IMPROVEMENT IS NOT UNIFORM WITH DEPTH.

PRELIMINARY TESTS (TRIAL) ARE NECESSARY.PRELIMINARY TESTS (TRIAL) ARE NECESSARY.

A SUITABLE METHOD OF CONTROLLING THE COMPACTION A SUITABLE METHOD OF CONTROLLING THE COMPACTION

IS ESSENTIAL (PRE&POST TESTS)IS ESSENTIAL (PRE&POST TESTS)

GENERALLY IT IS BELIEVED THAT PLASTIC SATURATED GENERALLY IT IS BELIEVED THAT PLASTIC SATURATED

CLAYS ARE NOT SUITABLE FOR TAMPING. LOW PLASTICITY CLAYS ARE NOT SUITABLE FOR TAMPING. LOW PLASTICITY

COHESIVE SOILS MAY BE SUITABLE.COHESIVE SOILS MAY BE SUITABLE.



wave propagation under impact (after R.D.WOODS)

BLASTINGBLASTINGPRINCIPLE OF THE METHOD:PRINCIPLE OF THE METHOD: BY BLASTING BURIED BY BLASTING BURIED

EXPLOSIVES (DYNAMITE, TNT, AMMONITE ETC.) EXPLOSIVES (DYNAMITE, TNT, AMMONITE ETC.)

LONGITUDINAL AND SHEAR DETONATION WAVES ARE LONGITUDINAL AND SHEAR DETONATION WAVES ARE

PRODUCED.PRODUCED.

APPLIED TO MAINLY LOOSE, COHESIONLESS, SATURATED APPLIED TO MAINLY LOOSE, COHESIONLESS, SATURATED

SOILS (MOST SUITABLE)SOILS (MOST SUITABLE)

BLASTING CAUSES LIQUEFACTION, AND THEREFORE SOIL BLASTING CAUSES LIQUEFACTION, AND THEREFORE SOIL

STRUCTURE IS BROKENSTRUCTURE IS BROKEN

AFTER BLASTING, WATER AND GAS IS EXPELLED.AFTER BLASTING, WATER AND GAS IS EXPELLED.

DENSIFICATION OCCURSDENSIFICATION OCCURS

SAND BOILS AT THE SURFACE (CRATERING IS AVOIDED)SAND BOILS AT THE SURFACE (CRATERING IS AVOIDED)CE-464 Ground ImprovementCE-464 Ground Improvement

PROCEDURE PROCEDURE ::

1.1. PIPE IS INSTALLED TO THE PIPE IS INSTALLED TO THE

DESIRED DEPTH (BY JETTING, DESIRED DEPTH (BY JETTING,

VIBRATING ETC.)VIBRATING ETC.)..

2.2. CHARGE IS PLACED IN THE PIPECHARGE IS PLACED IN THE PIPE..

3.3. PIPE IS WITHDRAWN AND THE PIPE IS WITHDRAWN AND THE

HOLE IS BACKFILLED (SOMETIMES HOLE IS BACKFILLED (SOMETIMES

PIPES ARE LEFT IN PLACEPIPES ARE LEFT IN PLACE AND AND

FIXED LATER ON)FIXED LATER ON)..

4.4. THE CHARGES ARE DETONATED THE CHARGES ARE DETONATED

ACCORDING TO THE PRE-ACCORDING TO THE PRE-

ESTABLISHED PATTERNESTABLISHED PATTERN..


MAJOR SETTLEMENT FOLLOWS THE BLAST, SMALLER MAJOR SETTLEMENT FOLLOWS THE BLAST, SMALLER

SETLEMENTS LAST FOR THE NEXT FEW MINUTESSETLEMENTS LAST FOR THE NEXT FEW MINUTES..

PIEZOMETERS ARE USUALLY INSTALLEDPIEZOMETERS ARE USUALLY INSTALLED..

DENSER (STRONGER) THE SAND AND HIGHER DR AND DENSER (STRONGER) THE SAND AND HIGHER DR AND

GREATER THE REQUIRED DEPTH FOR DENSIFICATION NEEDS GREATER THE REQUIRED DEPTH FOR DENSIFICATION NEEDS

GREATER AMOUNTS OF EXPLOSIVES (BLAST) TO BE USED (I.E. GREATER AMOUNTS OF EXPLOSIVES (BLAST) TO BE USED (I.E.

HIGHER ENERGY REQUIRED)HIGHER ENERGY REQUIRED)..

SUITABILITY AS FAR AS GRAIN SIZE DISTRIBUTION IS SUITABILITY AS FAR AS GRAIN SIZE DISTRIBUTION IS

CONCERNED IS SAME AS VIBROFLOATATIONCONCERNED IS SAME AS VIBROFLOATATION..

LYMAN REPORTS EFFECTIVENESS IN SILTY SOILS. WILD & LYMAN REPORTS EFFECTIVENESS IN SILTY SOILS. WILD &

HASLAM FOUND THE METHOD EFFECTIVE IN A MICACEOUS SAND HASLAM FOUND THE METHOD EFFECTIVE IN A MICACEOUS SAND

(75 % OF THE PARTICLES SMALLER THAN NO: 200 SIEVE). PRUGH (75 % OF THE PARTICLES SMALLER THAN NO: 200 SIEVE). PRUGH

FOUND THAT CLAY POCKETS REDUCE THE EFFICIENCY FOUND THAT CLAY POCKETS REDUCE THE EFFICIENCY

DRASTICALLYDRASTICALLY..


PARTLY SATURATED SOILS MAY BE SATURATED ARTIFICIALLYPARTLY SATURATED SOILS MAY BE SATURATED ARTIFICIALLY..

NO GENERALLY ACCEPTED DESIGN PROCEDURES ARE NO GENERALLY ACCEPTED DESIGN PROCEDURES ARE

AVAILABLE. CONDUCT FIELD TRIALS AND/OR FOLLOW AVAILABLE. CONDUCT FIELD TRIALS AND/OR FOLLOW

GENERAL GUIDELINES FROM PREVIOUS EXPERIENCES AND GENERAL GUIDELINES FROM PREVIOUS EXPERIENCES AND

STUDIES FOR A GOOD APPLICATION.STUDIES FOR A GOOD APPLICATION.

IVANOV (1967) EXPERIENCES UP TO 20 M DEPTH.IVANOV (1967) EXPERIENCES UP TO 20 M DEPTH.

CHARGE SIZECHARGE SIZE : < 1 - 12 kg : < 1 - 12 kg

DEPTH OF BURIALDEPTH OF BURIAL ‘D’ ‘D’

((CENTER OF CHARGECENTER OF CHARGE))

D> H/4 - D=HD> H/4 - D=H

ANOTHER RECOMMENDATIONANOTHER RECOMMENDATION D = 0.67 HD = 0.67 H


CHARGE SPACING IN PLANCHARGE SPACING IN PLAN : : 3-15 m3-15 m

NUMBER OF COVERAGESNUMBER OF COVERAGES : 1-5 ( : 1-5 (2-32-3 usual) usual)

EACH COVERAGE CONSISTSEACH COVERAGE CONSISTS OR A NUMBER INDIVIDUAL OR A NUMBER INDIVIDUAL

CHARGES.CHARGES.

TOTAL EXPLOSIVE USETOTAL EXPLOSIVE USE : 8-150 : 8-150 g/mg/m33 ( (10-3010-30 g/m g/m33 typical) typical)

SURFACE SETTLEMENTSURFACE SETTLEMENT : : 2-10 %2-10 % of layer thickness of layer thickness

DEPTH OF TREATMENT : VARIABLE, APPLICATIONS UP TO 30-DEPTH OF TREATMENT : VARIABLE, APPLICATIONS UP TO 30-

40 40 mm ARE QUOTED; ARE QUOTED;

PRACTICAL LIMIT: TO PLACE THE REQUIRED PRACTICAL LIMIT: TO PLACE THE REQUIRED

CONCENTRATED CHARGES TO THE REQUIRED DEPTH.CONCENTRATED CHARGES TO THE REQUIRED DEPTH.


AS 'H' INCREASES AS 'H' INCREASES 00 AND D AND Drr ALSO INCREASE WITH INCREASING ALSO INCREASE WITH INCREASING

ENERGY REQUIRED, DECREASING RADIUS OF INFLUENCE.ENERGY REQUIRED, DECREASING RADIUS OF INFLUENCE.

IVANOV 1987IVANOV 1987

where ; where ; PPmaxmax IS THE MAGNITUDE OF SHOCK WAVE IS THE MAGNITUDE OF SHOCK WAVE PRESSUREPRESSURE

(kg/cm(kg/cm22) )

C C IS THE SIZE OF CHARGEIS THE SIZE OF CHARGE, (kg of TNT) , (kg of TNT)

R R IS THE DISTANCE FROM CENTRE OF CHARGEIS THE DISTANCE FROM CENTRE OF CHARGE (m) (m)

11, , 22, k, k11, k, k22 ARE EMPIRICAL COEFFICIENTSARE EMPIRICAL COEFFICIENTS..

‘‘I’ IS THE IMPULSE PER UNIT AREAI’ IS THE IMPULSE PER UNIT AREA (kg.sec/cm (kg.sec/cm22))..

SOMETIMES THE RATIOSOMETIMES THE RATIO IS CALLED HOPKINSON'S NUMBERIS CALLED HOPKINSON'S NUMBER..


13

1max

R

CkP

2332

R

CCkI

R

C3

EVEN SMALL % GAS CAUSES DAMPING OF P - WAVE PRESSURES.EVEN SMALL % GAS CAUSES DAMPING OF P - WAVE PRESSURES.

DENSIFICATION UP TO 75-80 % DR HAS BEEN POSSIBLE, SOMETIMES DENSIFICATION UP TO 75-80 % DR HAS BEEN POSSIBLE, SOMETIMES

ERRATIC RESULTS OCCUR, INITIALLY DENSE LAYERS MAY BE ERRATIC RESULTS OCCUR, INITIALLY DENSE LAYERS MAY BE

LOOSENED.LOOSENED.

UPPER 1 - 2 UPPER 1 - 2 mm NOT EFFECTIVE AND COMPACTED BY SURFACE ROLLERS NOT EFFECTIVE AND COMPACTED BY SURFACE ROLLERS..

Gas Content (%) k1 1 k 2 2

Sand Below GWT

0.350.85

14

60045025045

Moist 8-10 % water

Moist 2-4 % water


LYMAN, 1942 GIVES THE FOLLOWING RELATIONSHIP BETWEEN LYMAN, 1942 GIVES THE FOLLOWING RELATIONSHIP BETWEEN

WEIGHT OF CHARGE, C, IN LBS AND RADIUS OF SPHERE OF WEIGHT OF CHARGE, C, IN LBS AND RADIUS OF SPHERE OF

INFLUENCE, R(ft),INFLUENCE, R(ft),

C = C = * * R3R3

= 0.0025 (0.062 m/ kg) for 60% Dynamite= 0.0025 (0.062 m/ kg) for 60% Dynamite

THE SIZE OF THE CHARGE ‘C’ (IN KG TNT) CAN BE TAKEN AS, THE SIZE OF THE CHARGE ‘C’ (IN KG TNT) CAN BE TAKEN AS,

ACCORDING TO IVANOV, 1978;ACCORDING TO IVANOV, 1978;

C = 0.055C = 0.055 * * dd33chch where dwhere d33

chch IS THE DEPTH OF CHARGE PLACEDIS THE DEPTH OF CHARGE PLACED..

KOK & TRENSE, 1979 BASED ON PRACTICAL EXPERIENCE THE KOK & TRENSE, 1979 BASED ON PRACTICAL EXPERIENCE THE

EFFECTIVE RADIUS, REFFECTIVE RADIUS, Reffeff (IN (IN mm) OF THE INFLUENCE OF BLASTING ) OF THE INFLUENCE OF BLASTING

(DEFINED AS THE RADIUS WITHIN WHICH FAIRLY UNIFORM (DEFINED AS THE RADIUS WITHIN WHICH FAIRLY UNIFORM

COMPACTION OCCURS AND APPROXIMATES THE BASE OF THE COMPACTION OCCURS AND APPROXIMATES THE BASE OF THE

SETTLEMENT SAUCER) CAN BE EXPRESSED AS;SETTLEMENT SAUCER) CAN BE EXPRESSED AS;

where K=2-5where K=2-5


3. CKReff

AS A RESULT OF BLASTING, LIQUEFACTION OCCURS WHICH IS AS A RESULT OF BLASTING, LIQUEFACTION OCCURS WHICH IS

THE POTENTIAL FOR DENSIFICATION.THE POTENTIAL FOR DENSIFICATION.

LIQUEFACTION COEFFICIENTLIQUEFACTION COEFFICIENT u/u/’’00

u : u : EXCESS POREWATER PRESSUREEXCESS POREWATER PRESSURE

’’00 : : EFFECTIVE OVERBURDEN PRESSURE PRIOR TO EFFECTIVE OVERBURDEN PRESSURE PRIOR TO

BLASTINGBLASTING

IF DEPTH EFFECT IS DISREGARDEDIF DEPTH EFFECT IS DISREGARDED : :

KOK & TRENSE, 1979 LIQUEFACTION OCCURS WHEN KOK & TRENSE, 1979 LIQUEFACTION OCCURS WHEN u/u/’’00

APPROACHES TO UNITYAPPROACHES TO UNITY..



R

C377.053.1

R

C364.065.1

R

C374.015.2

u/’0 VALUES

MIN MEAN MAX

This gives a mean value for the radius of liquefaction

30.2 C 38.2 CRliqu 37.4 C

MIN MEAN MAX

BARENDSEN & KOK (1983):BARENDSEN & KOK (1983):

IF IF THEN NO BOILING.THEN NO BOILING.


15.0/3 RC

THE MINIMUM DISTANCE R OF THE CHARGE CAN BE DEDUCEDTHE MINIMUM DISTANCE R OF THE CHARGE CAN BE DEDUCED


ACCORDING TO IVANOV (I983) OPTIMUM VALUE OF SUCH ACCORDING TO IVANOV (I983) OPTIMUM VALUE OF SUCH

CHARGES WOULD BE AT THE ORDER OF ABOUT 10 KG TNT.CHARGES WOULD BE AT THE ORDER OF ABOUT 10 KG TNT.

HOPKINSON NUMBER IS ALSO A MEASURE OF SETTLEMENT HOPKINSON NUMBER IS ALSO A MEASURE OF SETTLEMENT

OF THE SOIL LAYER, WITH INITIAL THICKNESS H, WHEN OF THE SOIL LAYER, WITH INITIAL THICKNESS H, WHEN

TREATED WITH EXPLOSIVES;TREATED WITH EXPLOSIVES;


)/(. 3 RCHs

EXPERIMENTALLY FOR AMSTERDAM HARBOUR:

)/ln(9.073.2 3 RCs

AFTER BLASTING PENETRATION RESISTANCES IN LOOSE AFTER BLASTING PENETRATION RESISTANCES IN LOOSE SOILS DO NOT INCREASE IMMEDIATELY BUT GRADUALLYSOILS DO NOT INCREASE IMMEDIATELY BUT GRADUALLY ! !

VERY DENSE LAYERS MAY BE LOOSENED OR WEAKENED VERY DENSE LAYERS MAY BE LOOSENED OR WEAKENED BY BLAST BUT OVERALL EFFECT IS POSITIVE.BY BLAST BUT OVERALL EFFECT IS POSITIVE.

REPEATED SHOTS ARE MORE EFFECTIVE THAN A SINGLE REPEATED SHOTS ARE MORE EFFECTIVE THAN A SINGLE LARGE ONE OR SEVERAL SMALL ONES DETONATED LARGE ONE OR SEVERAL SMALL ONES DETONATED SIMULTANEOUSLYSIMULTANEOUSLY..

DELAYED BLASTING (1-5 SEC) IS MORE EFFECTIVE THAN DELAYED BLASTING (1-5 SEC) IS MORE EFFECTIVE THAN ORDINARY BLASTINGORDINARY BLASTING..

WHEN A SERIES OF COVERAGES ARE USED THE SURFACE WHEN A SERIES OF COVERAGES ARE USED THE SURFACE SETTLEMENT ACCOMPANYINGSETTLEMENT ACCOMPANYING EACH COVERAGE IS EACH COVERAGE IS USUALLY LESS THAN THE ONE PROCEEDING.USUALLY LESS THAN THE ONE PROCEEDING.


DEPTH SHOULD BE GREATER THAN R IF SURFACE DEPTH SHOULD BE GREATER THAN R IF SURFACE

CRATERING IS TO BE AVOIDEDCRATERING IS TO BE AVOIDED..

MOST WIDELY USED EXPLOSIVES ARE 60 % DYNAMITE, 30% MOST WIDELY USED EXPLOSIVES ARE 60 % DYNAMITE, 30%

SPECIAL GELATINE DYNAMITE AND AMMONITE.SPECIAL GELATINE DYNAMITE AND AMMONITE.

USING EXPLOSIVES FOR COMPACTION RELATIVE DENSITIES USING EXPLOSIVES FOR COMPACTION RELATIVE DENSITIES

DR OF LOOSE SAND LAYERS CAN BE IMPROVED BY AN DR OF LOOSE SAND LAYERS CAN BE IMPROVED BY AN

AVERAGE OF AVERAGE OF DDrr = 15% UP TO 30% IF INITIAL DENSITY IS = 15% UP TO 30% IF INITIAL DENSITY IS

LOW ENOUGH (E.G. DLOW ENOUGH (E.G. Drr <50%)<50%)..

FOR MEDIUM DENSITIES WHICH SURPASS FOR INSTANCE FOR MEDIUM DENSITIES WHICH SURPASS FOR INSTANCE

DDrr = 60 % A NOTICABLE IMPROVEMENT IS OFTEN VERY = 60 % A NOTICABLE IMPROVEMENT IS OFTEN VERY

DIFFICULTDIFFICULT..



HYDRO-BLASTING TECHNIQUE HAS BEEN USED VERY

SUCCESFULLY IN USSR IN LOESS DEPOSITS (COLLAPSIBLE)

THERE ARE MAINLY TWO PROBLEMS ASSOCIATED WITH BLASTING.•EFFECTS ON ADJACENT STRUCTURES•EFFECTS ON PEOPLE

deep compaction

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