FM 5-134 Pile Construction - ARMY

8/20/2019 FM 5-134 Pile Construction - ARMY

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18 April 1985

DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited.


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Preface

P-1. Purpose and scope. This manual is organized to be used as a fieldreference. Chapter 1 through 4 discuss piles, equipment, and installation.Information concerning design (less that of sheet piling structures) isprovided in chapters 5 through 7 for use when tactical and logisticalsituations dictate original design. These chapters are of primary interest toengineer staff officers planning pile construction when the standardinstallations, facilities, equipment and supplies of the Army FacilitiesComponent System (AFCS) are not used. The appendix presents infor-mation on piling materials not currently available through military supply.The glossary contains terms frequently used in pile design and construction,

acronyms, and abbreviations used in this manual.P-2. User information. The proponent agency of this publication is theUS Army Engineer School. Submit changes for improving this publicationon DA Form 2028 (Recommended Changes to Publications and BlankForms) and forward to US Army Engineer School, ATTN: ATZA-TD-P, FortBelvoir, Virginia 22080-5291.


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C H A P T E R 1

B A S I C C O N S I D E R A T I O N S

Section I. DEFINITIONS ANDCLASSIFICATIONS

1-1. Definitions.

a. Piles. A pile is a long, columnar elementmade of timber, steel, concrete, or acombination of these materials (discussed inchapter 2). Piles transmit foundation loads todeeper strata that sustain the loads safelyand prevent settling of the supportedstructure. Piles derive their support from acombination of skin friction along theembedded lengths and end bearing at the tipsor bottoms (figure l-l).

b. Piers. A pier is a pile used to support ahorizontal supporting span such as a bridgeor archway.

c. Sheet piles. Sheet piles are generallyprefabricated or precast members drivenvertically into the ground to form a con-tinuous vertical wall. Sheet piles protect bearing piles against scour and the danger of undermining a pier foundation (figure 1-2).They form retaining walls (bulkheads) for

waterfront structures (figure 1-3).

d. Friction/end-bearing piles. A pileembedded in soil with no pronounced bearingstratum at the tip is a friction pile (figure 1-4).

A pile driven through relatively weak orcompressible soils into rock or an underlyingstronger material is an end-bearing pile(figure 1-5).

e. Batter piles. Piles driven at an angle are batter piles. They are used to resist heavylateral or inclined loads or where thefoundation material immediately beneath thestructure offers little or no resistance to thelateral movement of vertical piles. Battersare driven into a compressible soil to spread

vertical loads over a larger area, therebyreducing settlement. They may be used alone(battered in opposite directions) or incombination with vertical piles (figure 1-6).Batter piles can be driven at slopes of 4degrees to 12 degrees with ordinary drivingequipment.

f. Compaction piles. Compaction piles aredriven to increase the density of loose,cohesionless soils (figure 1-7) and to reducesettlement, since shallow foundations on veryloose deposits of sand or gravel may settle

excessively. Piles with a heavy taper are

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most effective and economical. These pilesderive their support primarily from friction.

g. Anchor piles. Anchor piles are driven toresist tension loads. In hydraulic structures,there may be a hydrostatic uplift load that isgreater than the downward load on thestructure. Anchor piles may be used to anchor

bulkheads, retaining walls, and guy wires(figure 1-3).

h. Fender piles. Fender piles are drivento protect piers, docks, and bridges fromthe wear and shock of approaching shipsand floating objects such as ice and debris(figure 1-3).

i. Dolphins. A dolphin is a group of piles

driven in clusters to aid in maneuveringships in docking operations. These dolphinsserve the same protective functions as fenderpiles (figure 1-3).

1-2. Pile functions.

Several uses of piles are illustrated in figures1-1 through 1-7. A pile or series of piles areused to constructor reinforce construction to

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To eliminate objectionable settlement.

To resist lateral loads.

To serve as fenders to absorb wear andshock.

To improve load-bearing capacity of soiland reduce potential settlement.

To transfer loads from overwaterstructures below the depth of scour.

To anchor structures subjected tohydrostatic uplift, soil expansion, oroverturning.

Section II. PILE SELECTION

1-3. Factors.

Many factors influence the choice of pile

types used on a given project. Considerationmust be given to the following factors (andothers, if applicable).

establish a stable foundation. Piles are usedas follows.

To transfer the structural load throughmaterial or strata of poor bearing capacityto one of adequate bearing capacity.

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Type of construction.

Availability of pile types and sizes.

Soil and groundwater conditions at thesite.

Anticipated pile loads.

Driving chacteristics of available piles.

Capabilities of crew and equipment avail-able for handling and driving piles.

Time available for construction.

Design life of structure.

Exposure conditions.

Accessibility of site and transportationfacilities.

Comparative costs.

14. Construction consideration.

a. Material selection. Piles are made fromtimber, steel, or concrete. Composite piles,formed of one material in the lower sectionand another in the upper, are not commonlyused in military construction because of thedifficulty in forming a suitable joint and thegreater complexity of installation.

b. Deliberate construction. Criticalstructures such as wharves, piers, and bridgeson main routes of communication must bewell constructed. Deliberate structureswarrant high safety factors. These structuresrequire thorough soil investigation and siteexamination to obtain the information forproper planning and design. This informationis essential for safety, economy, andpracticality.

c. Hasty construction. In military

construction, many pile structures are builthastily after limited reconnaissance. Hasty

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pile structures are designed with the lowest

factors of safety consistent with theirimportance. In hasty construction readilyavailable materials will be used to constructpile foundations capable of supporting thestructure at maximum load for immediateneeds. They can be strengthened or rebuiltlater.

1-5. Types and sizes.

Piles are classified by use, installation,material, and type of displacement. Clas-sification of piles based on installation

technique is given in table 1-1.

a. Large displacement. Large displacementpiles include all solid piles such as timber andprecast concrete piles. These piles may beformed at the site or preformed. Steel pilesand hollow concrete piles, driven closed-ended, also fall within this group.

b. Small displacement. Small displacementpiles include steel H-piles, steel pipe piles (if the ground enters freely during driving),screw or anchor piles, and preformed piles

driven in prebored holes.

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c. Nondisplacement. Nondisplacement

piles are formed by boring or other methodsof excavation. The borehole may be linedwith a casing that is either left in place orextracted as the hole is filled with concrete.

1-6. Soil and groundwater.

Soil and groundwater conditions determiuethe design and construction of pile foun-dations. Foundations are successful only if the soil strata, to which the structural loadsare transmitted, can support the loads withoutfailure or excessive settlement. Except for

end-bearing piles founded on rock, pilesdepend upon the surrounding soil or that beneath the pile tips for support. Groundwaterconditions often dictate the type of piles thatmust be used and influence the load-carryingcapacity of piles. Adequate soil exploration,testing, and analysis are prerequisites to thesuccessful design and construction of allexcept crude, hasty pile structures. Therelation of soil conditions to pile driving andthe design of pile f oundations are discussedin chapters 5 and 6.


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1-7. Comparative costs. piling materials on the basis of cost per linearfoot is misleading since the costs of shipping

Comparative costs of piling materials are and handling, the job conditions affectingcomputed on the dollar cost per ton of bearing driving techniques, and the relative load-capacity for the entire foundation. Comparing bearing capacities all affect the overall cost.

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C H A P T E R 2

MATERIALS

Section I. SELECTION OF MATERIALS

2-1. Considerations.The varied factors to be considered inselecting piles is covered in chapter 1, sectionII Chapter 2 discusses selection of piles based on the type of construction and theavailability and physical properties of thematerials.

a. Hasty construction. In hasty con-struction, full use is made of any readilyavailable materials for pile foundationscapable of supporting the superstructure and

maximum load during a short term. Thetactical situation, available time, andeconomy of construction effort dictateconstruction.

b. Deliberate construction. In a theater of operations, timber piles are normally avail-able in lengths of 30 to 70 feet. They are alsorelatively easy to transport and manipulate.Steel piling is next in importance, especiallywhere deliberate construction is planned toaccommodate heavy loads or where the

foundation is expected to be used for a longtime. Small displacement steel H-piles are

particularly suited to penetrating deep layersof course gravel, boulders, or soft rock such ascoral. Such piles also reduce heave of adjacentstructures.

2-2. Army Facilities ComponentsSystem (AFCS) materials.

Complete bills of materials for facilities andinstallations of the AFCS are in TM 5-303.These detailed listings, identified by facilitynumber and description, provide stocknumber, nomenclature, unit, and quantityrequired. For additional information con-cerning AFCS installations involving pile

foundations, consult TM 5-301 and TM 5-302.

Section II. TIMBER PILES

2-3. Classification.

The American Society for Testing andMaterials (ASTM) classifies timber pilesaccording to their intended use (table 2-l).Class A and class B piles are identical inquality, but differ in size. Class C piles (notlisted) normally are not treated with pre-

servatives. Timber piles are further classifiedin terms of marine and nonmarine use.

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a. Marine use. (2) Type II. Type II piles, pressure treatedwith creosote, are suitable for use in marinewaters of severe borer hazard.

(1) Type I. Type I piles, pressure treatedwith waterborne preservatives and creo- (3) Type III. Type III piles, pressure treated

sote (dual treatment), are suitable for use with creosote, are suitable for use in marinein marine waters of extreme borer hazard. waters of moderate borer hazard.

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b. Nonmarine use.

(1) Type I. Type I piles are untreated.

(2) Type II. Type II piles are treated.

2-4. Characteristics.

A good timber pile has the followingcharacteristics.

Free of sharp bends, large or loose knots,shakes, splits, and decay.

A straight core between the butt and tipwithin the body of the pile.

Uniform taper from butt to tip.

2-5. Source.

Usually, timber piles are straight tree trunkscut off above ground swell, with branchesclosely trimmed and bark removed (figure2-l). Occasionally, sawed timber may be usedas bearing piles.

2-6. Strength.

The allowable load on timber piles is basedon pile size, allowable working stress, soilconditions, and available driving equipment.These f actors are discussed in chapters 5

through 7. The customary allowable load ontimber piles is between 10 and 30 tons. Higherloads generally require verification bypile load tests. For piles designed as columns,working stresses (compression parallel to thegrain) for various types of timber are listed intable 2-2.

2-7. Durability.

A principal disadvantage of timber piles islack of durability under certain conditions.Piles are subject to fungi (decay), insects, and

marine borers. Design life depends on thespecies and condition of the wood, the amount

and type of preservative treatment, the degreeof exposure, and other factors. Chapter 8discusses maintenance and rehabilitation.

2-8. Availability.

Timber suitable for piling is abundant inmany parts of the world (see appendix).Timber piling may be obtained from localstocks or cut from standing timber. Thenative stock may be used untreated, or apreservative may be applied as discussed inchapter 8.

2-9. Maintenance.

Because of deterioration, considerabletreatment and maintenance is required on

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timber piles. Maintenance is discussed inchapter 8.

2-10. Other properties.

a. Length. Length maybe adjusted by simplecarpentry (sawing). Timber piles may be cut

off if they do not penetrate as far as esti-mated. Piles driven into water substrata can be adjusted by sawing off the pile tops abovewater level. They can also be sawed under-water using a saw supported by a frameworkabove the water level. Short piles may beeasily spliced.

b. Flexibility. Timber piles are more flexibilethan steel or concrete piles which makesthem useful in fenders, dolphins, small piers,and similar structures. They will deflectconsiderably, offer lateral resistance, andspring back into position absorbing the shockof a docking ship or other impact.

c. Fire susceptibility. Timber piles ex-tending above the water line, as in trestles orwaterfront structures, are susceptible todamage or destruction by fire.

2-11. Shipping and handling.

Timber piles are easy to handle and ship because they are relatively light and strong.Because they float, they can be transported by rafting particularly for waterfront struc-tures. They can be pulled, cleaned, and reusedfor supplementary construction such as false-work, trestles, and work platforms.

Section III. STEEL PILES


Steel piles are usually rolled H-sections orpipe piles; although wide-flange (WF) beamsare sometimes used. In the H-pile, the flanges

and web are of equal thickness. The standardWF shapes have a thinner web than flange.

The 14-inch H-pile section weighing 73 poundsper linear foot and the 12-inch H-pile sectionweighing 53 pounds per linear foot are usedmost frequently in military construction.

a. H-piles. Steel H-piles are widely usedwhen conditions call for hard driving, great

lengths, or high working loads per pile. Theypenetrate into the ground more readily thanother types, partly because they displacerelatively little material. They are par-ticularly suitable, therefore, when the bearingstratum is at great depth. Steel piles areadjustable in length by cutting, splicing, orwelding.

b. Pipe piles. Pipe piles are either welded orseamless steel pipes which may be drivenopen-ended or closed-ended.

c. Railroad-rail piles. Railroad rails can beformed into piles as shown in figure 2-2. Thisis useful when other sources of piles are notavailable.

d. Other. Structured steel such as I-beams,channels, and steel pipe are often availablefrom captured, salvaged, or local sources.With resourceful design and installation, theycan be used as piles when other, moreconventional piles are not available.

2-13.Characteristicsa. Resilience. A steel pile is not as resilientas a timber pile; nevertheless, it is strong andelastic. Large lateral loads may causeoverstressing and permanent deformation of the steel, although the pile probably will not break. A steel pile may be bent and evenkinked to some degree and still support alarge load.

b. Penetration.

(1) H-piles. A steel H-pile will drive easilyin clay soils. The static load generally will

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be greater than the driving resistance pile and be carried down with it. The coreindicates because the skin friction in- of soil trapped on each side of the web will

creases after rest. In stiffer clays, the pile cause the pile to act as a large displacementmay have the soil compacted between the pile.flanges in driving. The clay may grip the

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(2) Pipe piles. Pipe piles driven open-endpermit greater driving depths, as less soildisplacement occurs. Pipe piles can bereadily inspected after driving. If small boulders are encountered during driving,they may be broken by a chopping bit or

blasting. Pipe piles are often filled withconcrete after driving.

2-14. Source.

a. AFCS. Steel piles can be obtained fromAFCS as described in paragraph 2-2.

b. Local supply. In combat, piles or materialto construct them can be obtained fromcaptured enemy stock or from the localeconomy within a theater of operations. Full

use should be made of such captured,salvaged, or local materials by substitutingthem for the standard steel bearing pilingindicated by AFCS. Old or new rail sectionsmay be available from military supplychannels, captured stocks, or unused rails incaptured territory. Figure 2-2 shows methodsof welding steel rails to form expedient piles.Such expedient piles are usually fabricated inlengths of 30 feet.

2-15. Strength.

The strength of permitting long

steel piles is high, thuslengths to be handled.

Lengths up to 100 feet are not uncommon,although piles greater than 60 feet requirecareful handling to avoid excessive bendingstresses. Pipe piles are somewhat stiffer thanrolled steel sections. The allowable load onsteel piles is based on the cross-sectionalarea, the allowable working stress, soilconditions, and available driving equipment.The maximum allowable stress is generallytaken as 0.35 to 0.50 times the yield strength

with a value of 12,000 pounds per square inch(psi) used frequently. Allowable loads onsteel piles vary between 50 and 200 tons.

2-16. Durability.

Although deterioration is not a matter of great concern in military structures, steel

bearing piles are subject to corrosion anddeterioration. The effects of corrosion,

preventive measures taken to protect steelpiles, and remedial measures to correctprevious damage are discussed in chapter 8.


a. Transporting. Although quite heavy,steel piles are easy to handle and ship. Theycan be transported by rail, water, or truck.Precautions should be taken during shippingand handling to prevent kinking of flanges orpermanent deformation. Steel pipes must beproperly stored to prevent mechanical

damages.

b. Lifting and stacking. H-piles can belifted from the transport with a special slipon clamp and a bridle sling from a crane.Clamps are attached at points from one fifthto one fourth of the length from each end toequalize the stress. To make lifting easier, asmall hole may be burned in a flange betweenthe upper third and quarter points. Then ashackle may be attached to lift the piles intothe leads. Piles should be stacked on timbersso that they are kept reasonably straight.

Section IV. PRECAST CONCRETEPILES


Precast concrete piles are steel-reinforcedmembers (sometimes prestressed) of uniformcircular, square, or octagonal section, with orwithout a taper at the tip (figure 2-3). Precastpiles range up to 40 or 50 feet in lengthalthough longer lengths may be obtained if

the piles are prestressed. Classification is basically by shape and is covered inparagraph 2-20.

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2-19. Characteristics. difficulty requiring both the chiseling of theconcrete and the cutting of the reinforcing

Precast piles are strong, durable and may be rods.cast to the designed shape for the particularapplication. The process of precasting is not 2-20. Source.available in the theater of operations. They

are difficult to handle unless prestressed, and Precast concrete piles are manufactured in athey displace considerable ground during casting yard, at the job site, or at a centraldriving. Length adjustment is a major location. The casting yard is arranged so the

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piles can be lifted from their forms andtransported to the pile driver with a minimumof handling (figure 2-4). The casting yardincludes storage space for aggregates andcement, mixing unit, forms, floor area for thecasting operations, and sufficient storagespace for the completed piles. The casting

yard should have a well-drained surface thatis firm enough to prevent warping during the

period between placement and hardening.Cement and aggregates may be handled bywheelbarrows or buggies. Additional storagespace may be needed for the completed piles.

a. Forms. Forms for piles may be of wood(figure 2-5) or metal. They must be tight to

prevent leakage, firmly braced, and designedfor assembly and disassembly so that they

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can be reused. Forms must be thoroughlycleaned and oiled with a nonstaining oil before use.

b. Reinforcement. For precast concrete pilessubjected to axial loadings, steel rein-forcement provides resistance to the stresses

caused by handling and driving. Threemethods of handling concrete piles areillustrated in figure 2-6. Depending on themethod used, the size and number of longitudinal reinforcement bars aredetermined from design charts in figure 2-7.These charts are based upon an allowablestress of 1,400 psi in the concrete and 20,000psi in the steel, without allowance for impact.Minimum reinforcement cages are assembledas shown in figure 2-4. Adequate spiralreinforcing at the pile head and tip isnecessary to reduce the tendency of the pile tosplit or span during driving.

c. Placement. When concrete is placed inthe forms by hand, it should be of plasticconsistency with a 3-inch to 4-inch slump.Use a concrete mix having a l-inch to 2-inchslump with concrete vibrators. Reinforcementshould be properly positioned and securedwhile the concrete is placed and vibrated.Details concerning the design of concrete

mixes are contained in TM 5-742.d. Curing. Forms should not be removed forat least 24 hours after concrete is placed.Following the removal of the forms, the pilesmust be kept wet for at least seven days whenregular portland cement is used, and threedays when high-early strength cement isused. Curing methods are discussed in TM5-742. Pending and saturated straw, sand, or burlap give good results. The piles should not be moved or driven until they have acquiredsufficient strength to prevent damage. Each

pile should be marked with a referencenumber and the date of casting.

2-21. Strength.

Precast concrete piles can be driven to highresistance without damage. They are as-signed greater allowable loads than timberpiles. As with other pile types, allowableloads are based on the pile size, soilconditions, and other factors. Customaryallowable loads range from 20 to 60 tons for a10-inch diameter precast concrete pile and 70to 200 tons for an 18-inch square precastconcrete pile.

2-22. Durability.

Under ordinary conditions, concrete piles arenot subject to deterioration. They can be usedabove the water table. Refer to chapter 8 foradditional information on durability.

2-23. Availability.

Precast piles are available only when thecasting facility is nearby. See paragraph 2-20.

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a. Handling. Piles should be handled inaccordance with the procedure selected fordesign (figure 2-6). For placement, piles may be lifted by cables and hooks looped around

the pile at the desired point. To prevent wearto the cable, use short lengths of wood orother cushioning material, Piles designed fortwo-point support (figure 2-6, 3) and lifted bycables require the following arrangement.

A sheave is required at point A so that thecable will be continuous from point B overthe sheave at A to point C. This cable is anequalizer cable since the tension in ABmust be the same as that of AC. Unless anequalizer is used, care must be taken inlifting the pile so that tension in the cables

is equal; otherwise, the entire load mayrest on one end.

When the pile is raised to a verticalposition, another line, CD, is attached.When drawn up, the sheave at A shiftstoward C.

An additional line is needed with thiscable arrangement to prevent the pile fromgetting out of control when it is raised to avertical position.

b. Shipping and storage. If piles are to bestacked for storage or shipment, the blocking

between the tiers must be in vertical lines sothat a pile in a lower tier will not be subject to bending by the weight of the piles above. Anexample of improper stacking is shown infigure 2-8. A forklift or specially equippedfront-end loader can be used to move pilesfrom the storage area to the work area.Whenever possible, locate the casting site asclose as possible to the job site. Trans-portation by barge is the best method, if feasible.

Section V. CAST-IN-PLACE PILES


Cast-in-place piles are either cased oruncased. Both are made at the site by forming

a hole in the ground at the required locationand filling it with a properly designed con-crete mix.

a. Cased. The concrete of a cased pile is castinside a metal casing or pipe left in theground. The casing is driven to the requireddepth and cleaned before placement of concrete. If the casing is relatively thin, amandrel is used to drive the casing. Manydifferent kinds of shells and mandrels areavailable commercially, but not throughmilitary supply channels. Those of foreignmanufacture may be available in a theater of operation.

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b. Uncased. Uncased concrete piles referredto as drilled piers are frequently used. Variousaugers are used for drilling holes up to 72inches in diameter with depths up to 60 feet ormore. Auger holes are excavated by the dryprocess. The bottom of the pier maybe under-reamed at the base, if desired, to provide

greater end-bearing area or resistance againstuplift forces. Drilling mud advancing throughsubmerged granular materials keeps the holeopen. The dry shaft is filled with concrete. Atremie pipe is used through the drilling mud.Steel reinforcement may be used in theconcrete.

2-26.Characteristics.

The characteristics of cast-in-place pilesdepend greatly on the quality of workmanshipand characteristics of the soils and supportenvironment. Materials for concrete con-struction are readily available in manymilitary situations, thus drilled piers havesome military application. They require largediameter augers. Installation requires betterthan average workmanship. Groundwater isinfluential in determining the difficulty of installation. Even small inflow quantities of water may induce caving, thus requiring theuse of casing or drilling mud. Drilled pierscan provide a rapid and economical methodof pile installation under many conditions.

2-27. Strength and durability.

Cast-in-place piles are strong. Large loadscan be carried by cast-in-place piles dependingon the cross-sectional area of the pile. Likeprecast piles, cast-in-place piles are durable.If the pile is cased, even though the casingshould deteriorate, the concrete portion willremain intact.

2-28. Construction.

Construction of cast-in-place piles isdescribed in chapter 4.

Section VI. SHEET PILES

2-29.Classification.

Sheet piles vary in use and materials. Theymay be classified by their uses. They differfrom previously described piles in that they

are not bearing piles, but are retaining piles.Sheet piles are special shapes of interlockingpiles made of steel, wood, or concrete whichform a continuous wall to resist horizontalpressures resulting from earth or water loads.The term sheet piling is used interchangeablywith sheet piles.

2-30. Uses.

Sheet piles are used to resist earth and waterpressure as a part of a temporary orpermanent structure.

a. Bulkheads. Bulkheads are an integralpart of watefront structures such as wharvesand docks. In retaining structures, the sheetpiles depend on embedment support, as incantilever sheet piling, or embedment andanchorage at or near the top, as in anchoredsheet piling.

b. Cofferdams. Cofferdams exclude waterand earth from an excavation to facilitateconstruction.

c. Trench sheeting. Trench sheeting when braced at several points is termed bracedsheeting.

d. Small dams and cutoff walls. Sheetpiles may be used to form small dams andmore frequently cutoff walls beneath water-retaining structures to control seepagethrough the foundations.

e. Bridge piles. Sheet piles are used in theconstruction of bridges and left in place. For

example, a pier may be formed by drivingsteel sheet piling to create a circular enclosure,

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excavating the material inside to the desired available sizes and shapes are given indepth, and filling the enclosed space withconcrete.

f. Groins and sea walls. Sea walls areparallel to the coastline to prevent directwave and erosion damage. Groins or jettiesare perpendicular, or nearly so, to the coast-line to prevent damage from longshore

currents or tidal erosion of the shore when themotion of the water is parallel, or at an angle,to the shoreline.

2-31. Materials.

a. Steel sheet piling. Steel sheet pilingpossesses several advantage over othermaterials. It is resistant to high drivingstresses, is relatively lightweight, can beshortened or lengthened readily, and maybereused. It has a long service life, either aboveor below water, with modest protection. Sheet

piling available through military supplychannels is listed in table 2-3. Commercially

TM 5-312. The deep-arch web and Z-piles areused to resist large bending movements(figure 2-9). Sheet pile sections of foreignmanufacture, either steel or concrete, should

be used when available. The sizes andproperties may differ appreciably from typescommonly available in the United States.

b. Fabricated timber sheet piling. Timbersheet piling may be fabricated for temporarystructures when lateral loads are relativelylight. Timber used in permanent structuresabove water level requires preservativetreatment as described for timber piles(chapter 8). Various types of timber sheetpiling are shown in figure 2-10. The heads arenormally chamfered and the foot is cut at a 60degree slope to force piles together duringdriving.

(1) Wakefield sheet piling. Wake field pilingis used in water and where hard driving is

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anticipated. Three rows of equal width a tongue-and-groove can be provided byplanking are nailed and bolted together so nailing a strip of wood on one edge formingthat the two outer planks form the groove

and the middle plank forms the tongue.Three 2-inch x 12-inch or three 3-inch x12-inch planks are usually used to formeach pile. Two bolts on 6-foot centers andtwo rows of spikes on 18-inch centers between the bolts hold the planks together.When bolts are not used, the spikes should be driven in offset rows spaced 12 inchesapart.

(2) Tongue-and-groove piling. Milledtongue-and-groove piling is lightweightand used where watertightness is notrequired. If heavier timbers are available,

the tongue and two strips on the opposite

side forming the groove. Timber (6-inch x12-inch) may be interlocked by cutting2-inch grooves on each side and spiking aspline of hardwood, such as maple or oak,into one groove of the next timber.

(3) Offset timber sheet piling. An in-termediate type of sheet piling can befabricated consisting of two rows of 2-inchx 12-inch or 3-inch x 12-inch plankingwhich are bolted or spiked together so thatthe joints between the two rows of planks

are offset.

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c. Rail and plank sheet piling. Railroad d. Concrete sheet piling. Typical concreterails and planking can be used in expedient sheet piling (figure 2-12) may be advan-sheet piling (figure 2-11). The planks should tageous in military construction when be leveled along both edges to fit snugly materials for their construction are available.against the adjacent rail. This piling is Due to their strength and durability, theyinstalled by alternately driving a rail, then a adapt well to bulkhead construction.plank.

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C H A P T E R 3

P I L E - D R I V I N G E Q U I P M E N T

Section I. STANDARD PILE-DRIVINGEQUIPMENT

3-1. Basic driving and installingmethods.

Piles are installed or driven into the ground by a rig which supports the leads, raises thepile, and operates the hammer. Rigs areusually manufactured, but in the field theymay be expedient, that is, constructed withavailable materials. Modern commercial rigsuse vibratory drivers while most older andexpedient rigs use impact hammers. Theintent is the same, that is to drive the pile intothe ground (strata).

3-2. Rig mounting and attachments.

Pile-driving rigs are mounted in differentways, depending on their use. This includesrailway, barge, skid, crawler, and truck-mounted drivers. Specialized machines areavailable for driving piles. Most pile drivingin the theater of operations is performedusing a steel-frame, skid-mounted pile driveror power cranes, crawlers, or truck-mountedunits, with standard pile-driving attachment(figure 3-1). The attachments available

through military supply channels include

adapters (figure 3-2) used to connect the leadsto the top of the crane boom leads and acatwalk or lead braces used to connect thefoot of the leads to the base of the boom. Theleads and catwalk assembly support drophammers weighing up to 3,000 pounds anddiesel hammers weighing up to 13,000 pounds.

3-3. Steel-frame, skid-mounted piledrivers.

A steel-frame, skid-mounted pile driver witha gasoline-driven engine is a class IV item(figure 3-3). This pile driver may be used onthe ground or on any permanent structure orsturdy transport. It can drive vertical or

batter piles. The reach from the base of the boom to the front of the leads depends uponthe weight of the hammer and power units.Reach may be increased by ballasting the back of the skid frame, or by securing it to thedeck on which it rests to counterbalance theweight of the equipment. The skid-mountedpile driver consists of the followingcomponents.

a. Skid frame. The skid frame is two steelI-beams 40 feet long, crose-braced 8 feet apart

at the front of the frame and 12 feet apart at3-1


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the rear of the frame. A platform at the rear of c. Leads. Leads standard to the unit are onethe frame supports the winch.

b. Boom. A 45-foot boom is anchoredskid frame 16 feet from the front end.

3-2

8-foot top section, one 17-foot reversiblesection, one 10-foot extension, one 15-foot

to the intermediate section, and one 15-foot bottomsection, totaling 65 feet. The length of the


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lead may be reduced to 55 or 47 feet by leaving handles the hammer and pile lines. The leadsout sections. The length of the lead is to the skid-mounted pile driver can be tilteddetermined by the length of the pile to be transversely, longitudinally, or in a com-driven. The boom is attached to the midpoint bination of these as well as fore and aft of theof the top 20-foot section. A double-sheave vertical by adjusting the guides.

bracket, attached at the top of the leads.

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d. Guides. Two types of guides permit the frame to the leads. It fixes the positionversatile aligning of the leads. of the base of the leads and holds them

(1) Fore-bat t er guide. The fore-batter guidevertically or at a fore-batter in the plane of

(figure 3-3), referred to as a spotter, is athe longitudinal axis of the equipment

beam extending from the forward end of (figure 3-4, 2).

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(2) Moon beam. The moon beam (figure 3-3)is a curved beam placed transversely at theforward end of the skid frame to regulateside batter.

e. Drive unit. The drive unit (not providedas part of the pile-driver rig) is a 2-drumwinch driven by a gasoline, diesel, or steamengine. The drive unit is mounted on theplatform at the rear of the skid frame.

f. Hammer. A 5,000-pound, double-acting

steam or pneumatic hammer; a 1,800-pound

or 3,000-pound drop hammer; or an 8,000-foot-pound or 18,000-foot-pound dieselhammer may be used.

3-4. Driving devices (hammer andvibratory driver).

There are three impact hammers used forpile-driving: the drop hammer, the pneumaticor steam hammer, and the diesel hammer.Drop hammers and diesel hammers arestandard engineering equipment. Table 3-1

provides data on selected types of

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commercially available hammers. Vibratorydrivers/extractors are not classified ashammers and do not require pile caps forprotection against impact stresses. They areclamped to the pile to vibrate as a unit.

a. Drop hammers. The drop hammer (figure3-5) is a simple pile-driving hammerconsisting of a block of metal raised in theleads by the drive unit, then permitted todrop, striking the pile cap. Drop hammers arecumbersome, and their driving action is slowcompared to other hammers. Velocities atimpact are high and damage the top of a pile.Two standard drop hammers are available in

3-6

military supply channels: size one weighs1,800 pounds; size two weighs 3,000 pounds.The maximum height of fall should be limitedto six feet. For most efficient driving, theweight of a hammer twice that of the pile willgive the best results. As an expedient, a loghammer (figure 3-6) may be fabricated andused. Drop hammers should be used only inremote sites or for a small number of pilings.

b. Air or steam hammers. The air or steamhammers (figure 3-7) consist of stationarycylinders and moving rams which include a

piston and a striking head. The piston israised by compressed air or steam pressure. If


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the fall is gravity, the hammer is simpleacting. In double-acting hammers, the air or

steam pressure works on the upstroke anddownstroke. Because they provide a high rateof blows (90 to 150 blows per minute), theykeep the pile moving and prevent the buildingof friction thus enabling faster driving. Thedifferential-acting hammer uses higherpressures and lower volumes of air or steam.After being raised, the ram is valved to beused for the downstroke.

c. Diesel hammers.Diesel hammers areself-contained and need no air or steam lines.Fuel tanks are a part of the rig. Diesel

hammers are well suited for military

operations. Table 3-2 contains a list of dieselhammers available through military

channels and the types and sizes of pileswhich can be driven by each hammer. Sizes Aand D are suitable for use with 10-ton and20-ton drivers. Heavier hammers are moresuitable for use with 30-ton to 40-ton cranes.Diesel hammers may be either open-ended orclosed-ended as shown in figure 3-8.

Diesel hammers function as follows.

The ram is lifted by combustion of fueland compressed gas in a chamber betweenthe bottom of the ram and an anvil block in

the base of the housing.3-7


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The crane-load line raises the ram for the

initial stroke, and an automatic tripmechanism allows the ram to drop.

3-8

During this fall, fuel is injected into the

combustion chamber by a cam-actuatedfuel pump.


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Continuing its fall, the ram blocks the magnitude and duration of the drivingexhaust ports located in the cylinder and force.compresses the airlfuel mixture trapped

below it to ignition temperature. As the ram rises, the exhaust and intakeports are uncovered, combustion gases

When the ram hits the anvil, it delivers escape, and air enters. In the closed-endedits energy through the anvil to the pile. At type, the housing extends over the cylinderthe same time, combustion occurs which to form a bounce chamber in which air isdrives the ram upward. The pressure of the compressed by the rising ram. Air trapped burning gases acts on the anvil for a and compressed above the piston helps

significant time, thus increasing the

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stop the ram piston on its upward stroke 3-5. Caps and cushions.and accelerates it on its downward stroke.

The cycle is repeated.

d. Vibratory drivers/extractors.Vibratory drivers are a recent developmentin pile-driving equipment. They are used in

commercial pile construction, especially indriving sheet piling. They are not part of themilitary inventory. Vibratory drivers usuallyrequire either an auxiliary hydraulic orelectric power supply. They consist of thevibrating unit which includes the rotatingeccentric weights, the suspension system thatisolates the vibratory forces from the liftingdevice, and the clamping system whichconnects the vibratory driver to the pile.Vibratory drivers have short strokes, lessthan two inches, and high impulse rates, upto 2,000 pulses per minute. Their driving

ability derives from the vibrations and theweight of driver and pile.

Caps and cushions protect the top of the pileand reduce the damage caused by the impactof the hammer. Although they serve the samepurpose, they vary for different types of hammers.

a. Drop hammers. A standard driving capfor timber piles used with a drop hammer is acast block. Its lower face is recessed to fit overthe top of the pile, and its upper face isrecessed to receive an expandable block of hardwood in end-grained position to act as awasher (figure 3-5). The cap is fitted with awire rope sling so that the cap, as well as thehammer, may be raised to the top of the leadswhen positioning a pile in the leads.

b. Air and steam hammers. The ram of aVulcan hammer strikes a cap block positioned

in the base of the hammer. In other hammers,such as the MKT type, the rams strike directly

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on the base or anvil. The top of the pile isprotected by a driving cap suspended fromthe base of the hammer and fitted to thedimensions of the pile. Driving caps for steelH-piles are shown in figure 3-9. The tops of concrete piles are usually protected fromlocal overstress by a pile cushion inserted

between the drive head and the pile. The cap block and cushion serve several purposes;however, their primary function is to limit

impact stresses in both the pile and hammer.

Common types of cushion materials aresheets of Micarta with sheets of aluminum orlarge oak blocks in end-grained position.

c. Diesel hammers. Military dieselhammers are supplied with cushion blocksinserted between the anvil and the drive cap.The cushion blocks consist of laminatedplastic and aluminum or cast nylon. Ad-ditional cushioning is required between

concrete piles and the pile cushion.

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3-6. Pile-driving leads.

Pile-driving leads (figure 3-10) are tracks forsliding the hammer and guides to positionand steady the pile during the first part of thedriving. Standard steel leads are supplied inl-foot and 15-foot lengths. The 15-foot length

is the top section. Leads must be ap-proximately 20 feet longer than the pile toprovide space for the hammer and ac-cessories. There are three types of leads.

a. Swinging leads. Swinging leads arehung from the crane boom by a crane line.The bottoms of the leads are held in placewhile the boom is positioned so that the pile isplumb or at the desired batter. Swingingleads are the lightest, simplest, and leastexpensive. They permit driving piles in a holeor over the edge of an excavation. Swinging

leads require a three-line crane (leads,hammer, and pile). Precise positioning of theleads is slow and difficult.

b. Fixed, underhung leads. A spotter easilyand rapidly helps connect fixed, underhungleads to the boom point and to the front of thecrane. The leads are positioned by adjustingthe boom angle and spotter. A two-line craneis adequate to accurately locate the leads invarious positions. The length of the leads islimited by the boom length. Military standardleads are underhung from the crane boom

and fixed to the crane by a catwalk. They arecomprised of a 15-foot top section and therequired number of 10-foot lower sections tomake up the required length (see figure 3-l).

c. Fixed, extended leads.Fixed, extendedleads extend above the boom point. They areattached with a swivel connection whichallows movement in all directions. A spotterconnects the bottom of the leads to the frontof the crane. A two-line crane is required. Aheadblock directs the crane lines over the topof the leads. Once the leads are set up, theycan be positioned quickly and accurately;however, initial setup time is extensive. Side

to-side as well as fore-and-aft adjustment ispossible. The military standard skid-mountedpile-driving rig has fixed, extended leadswith capabilities of side-to-side and fore-and-aft batter.

3-7. Spotters and lead braces.

The spotter connects the bottom of fixedleads (underhung or extended) to the front of the crane. With military standard leads usedwith a crane, the catwalk connects betweenthe bottom of the leads and the front of thecrane’s revolving upper machinery deck. Ittelescopes for fore-and-aft batter. The front of

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the spotter is moved for and aft for batterpiles, and side to side to plumb piles eitherhydraulically or manually. Special bottom

braces are available which permit thisoperation (figure 3-11).

3-8. Followers.

Followers are fabricated pile extensionsplaced between the top of a pile and the

hammer. They are used when driving piling below the water surface, especially with adrop hammer (which operates with reducedefficiency underwater) and with the dieselhammer (which cannot operate underwater).Followers are used under fixed or swingingleads and in tight spaces where there is no

room for the leads and the hammer, as in aclose pile grouping. When followers are used,the computation of the bearing value of the

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pile using a dynamic formula is uncertain.Followers must be rugged and constructed totransmit the full impact of the hammer andto hold the hammer and the pile in positivealignment. Followers can be fabricated fortimber, steel, and sheet piling.

a. Timber pile follower. The follower ismade from around timber of hardwood 10-to20-feet long. The bottom of the timber isinserted into, and bolted to, a follower capwhich is recessed at the bottom the same as apile cap. The top is trimmed to fit into the pilecap or hammer. If there is insufficient drivingspace for a follower cap, a flared wrought-steel band is bolted to the bottom of thetimber follower.

b. Steel pile follower. For a steel pilefollower, a section of the driven pile isreinforced by welding steel plates at the headto lessen damage from repeated use. Ex-tension plates that fit snugly against the pileto be driven are welded to the base.

c. Sheet pile follower. Projecting platesare riveted on each side of the sheet pile beingdriven. These riveted plates are shaped to fitthe form of the pile.

Section II. EXPEDIENT ANDFLOATING PILE-DRIVINGEQUIPMENT

3-9. Expedient pile drivers.

When standard pile drivers are not available,expedient pile drivers may be constructed.

a. Wood-frame, skid-mounted piledriver. A skid frame is made of two 12-inch x17-inch timbers 44 feet long. The frame iscross braced with 8-inch x 8-inch and 12-inchx 12-inch timbers and stiffened on both sideswith a king post and king-post cables. Theleads are standard or expedient. Figure 3-12

shows expedient leads, 66 feet high made of

timber with the bearing surfaces faced withsteel plates to reduce wear and friction. Thefixed leads are supported by guys run to therear of the frame and by an A-frame from themidpoint of the leads to the midpoint of theframe. The rig can be skidded into placeusing a 2-drum winch. The rig is anchored,using natural anchors in the vicinity of the

site. Any pile-driver hammers discussed inparagraph 3-4 can be used.

b. Timber pile driver. Figure 3-13 shows arig with a 12-inch x 12-inch timber base andan A-frame using a section of standard leads.Cross braces are 3-inch x 12-inch members.The leads must be securely fastened to the tipof the A-frame and guyed at the base. Anotherdesign, using smaller dimensioned lumber, isshown in figure 3-14.

c. Tripod pile driver. Figure 3-15 shows a

hand-operated rig constructed of local

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materials. The hammer, guide rod, blocks,and line (rope) are the only equipment thatmust be transported. This rig is particularlywell adapted for jungle operations where thetransportation of heavy equipment is dif-ficult. The rig will handle short lengths of piling up to 8 inches in diameter. Figure 3-16

shows the design features of the pile driver.The spars are 8 to 10 inches in diameter and

are lashed with ½-inch line. The base framemust be ballasted while driving piles. A loghammer (figure 3-6) can be used to drive thepiles. The rig is built of hardwood and has asteel baseplate to protect the driving end. Theguide-rod hole and the guide rod must be wellgreased to prevent binding when the hammer

falls. The base of the guide rod is positioned by drilling a ¾-inch hole 6 to 8 inches deep in

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3-17


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the head of the pile. Guying the pile helps four-wheel-drive truck or the front wheels of position the guide rod. any front-wheel-drive truck.

d. Welded-angle construction pile driver. 3-10. Power for expedient pile drivers.A piledriving rig can be built using fourheavy steel angles as leads and a laminated To raise the pile into position and operate thesteel plate cap of welded and bolted hammer in driving the pile, power is required.construction. The leads should be heavily When available, the power unit for a standard braced and guyed (figure 3-17). The hammer skid-mounted pile driver should be used. Incan be operated by the rear wheels of any

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other cases a truck, truck motor, or manpowercan be used.

a. Truck. The hammer line can be snubbedto a truck bumper and the truck backed awayuntil the hammer is raised. The line is thenfreed allowing the hammer to fall (figure3-13). The wheels of a truck can be jacked andused as hoist drums (figure 3-17). The truckwinch should not be used except in emer-gencies since heavy use will cause excessivewear to the winch motor.

b. Truck motor. A truck motor can bemounted on the base frame of the rig. A drumis mounted on the drive shaft and controlled by the clutch. The hammer line is attached tothe drum.

c. Manpower. Hammers weighing up to1,200 pounds can be operated by 15-personcrews if there is sufficient pulling distance atthe site. Normally, a soldier hauling a linecan pull 50 to 80 pounds. When steel hammers

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are fabricated in laminated sections, they areeasier to hand-carry over difficult terrain.

3-11. Floating pile drivers.

a. Floating cranes. Barge-mounted cranescan be adapted for pile-driving operating byusing boom-point adapters and pile-drivingattachments. If standard leads are notavailable, they should be improvised fromdimensioned lumber faced with steel plateand adequately braced. For pile driving, afloating crane may be maneuvered with its

own lead lines, and spuds put down beforedriving begins.

b. Barges or rafts. Crane-shovel units orskid-mounted pile drivers may be mounted on barges or rafts for work afloat. Driving may be off the end or side of the raft, depending onproblems of current and maneuverability.Sandbags can counterbalance a raft to enablethe pile driver to be positioned close to the endof the raft to extend its reach. A standard4-foot x 7-foot barge assembly is adequate tosupport a pile driver adapted from a 12 ½-toncrane (figure 3-18). A pile driver adapted froma skid-mounted pile driver can be mounted ona 5-foot x 12-foot barge assembly (figure 3-19).

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c. Pneumatic floats. Cranes or skid-mounted pile drivers may be mounted onrafts assembled from pneumatic floats whichserve as platforms. Driving off the end or sideof the float using counterbalances (such assandbags) applies to this type of rig.

d. Anchoring of rafts. The raft must beheld securely to position the pile accuratelyand to hold the leads and hammer in linewith the pile during driving. For the first pileof an isolated off-shore structure, such as adolphin, two transverse lines on capstans at

bow and stern and one longitudinal line on adeck capstan will hold the craft if the floating

3-22

rig is not furnished with spuds. The first piledriven may be used as one of the anchors. It ispossible to run the steadying lines fromanchorages onshore. More control of the raftcan be obtained if the lines are run like springlines from a berthed ship, so that they crosseach other diagonally.

Section III. OTHER PILE-DRIVINGEQUIPMENT

3-12. Accessory equipment.

a. Support equipment. Equipment must beavailable for handling stockpiled piling and


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for straightening, cutting, splicing, capping, couplings. The pipes and fittings are madeand bracing piles. into a jetting assembly, and the water hoses

and couplings are used to connect the jettingb. Jetting equipment. Jetting is a method assembly to a water pump (figure 3-20).of forcing water around and under a pile toloosen and displace the surrounding soils. (1) Jet t i ng pipes. Jetting pipes are usually

Jetting operations are discussed in chapter 4, from 2½ to 3½ inches in diameter. The

section II. The equipment consists of steel pipes are reduced to about half theirpipes, pipe fittings, water hoses, and

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http://ch4.pdf/http://ch4.pdf/


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diameter to form nozzles at the point of discharge.

(2) Jet t i ng pump. The jetting pump must becapable of delivering 500 gallons perminute (gpm) at a pressure of 150 to 200pounds per square inch (psi). Gasoline or

diesel-powered centrifugal pumps havingfrom two to four stages and developingfrom 100 to 300 psi are normally used. Foruse in gravelly soils, water pressure shouldrange from 100 to 150 psi. For sands, waterpressure from 50 to 60 psi is generallyadequate.

(3) Jet t i ng sizes. Jet sizes are normally 2 ½inches for 250 gpm, 3 inches for 250 to 500gpm, and 3 ½ inches for 500 to 750 gpm.

(4) Jet t ing w i t h ai r . Air may be used for jetting either alone or with water. Aircompressors are required.

c. Sleeve. A sleeve is a 4-foot section of steelpipe bolted to the jaws of the hammer to holdthe pile in place for driving when leadscannot be used. A three-point suspensionkeeps the hammer fixed at the desired anglewhen driving batter piles (figure 3-21, 1).

d. Pants. Pants consist of parallel plates bolted to the hammer body. These fit over the

top of sheet piling that is being driven withoutthe use of leads and serve to guide the hammer(figure 3-21, 2).

3-13. Equipment selection.

In military pile construction, little op-portunity exists for selecting the equipmentused in a given operation. Reduction instandard military equipment items availablefrom the table of organization and equipment

(TOE) and class IV equipment has simplifiedthis problem. When selection is possible,consider the following factors.

a. Ground conditions. Stable soil con.ditions permit the use of truck-mountedcranes, while boggy areas require crawler-mounted units.

b. Piles. The number, size, and length of piles affect the choice of equipment. Diesel,air, or steam hammers are used to drive

batter piles. Long piles require a large rigwith long leads. It is better to drive a long pileas a continuous section than to drive shortsections since alignment is controlled.

c. Hammers. Selection of the type and size of hammer will depend on availability, the typeof pile, and the anticipated loadings.

For air and steam hammers (singleacting or double-acting) the ratio of ram

weight to pile weight should fall between1:1 and 1:2. For diesel hammers, the ratioshould fall between 1:1 and 1:4.

All types of air, steam, and dieselhammers can be used to drive timber pilesprovided they have energy ratings between15,000 and 20,000 foot-pounds. Hammerswith a rated energy up to 26,000 foot-pounds can be used for timber piles with butt diameters of 15 inches or more. Specificguidance for selecting the size of dieselhammers is provided in table 3-1.

Except for diesel hammers, the size of thehammer selected should be one in whichthe desired energy is developed by heavyrams striking at low velocity. A highvelocity impact wastes a large amount of the striking energy. It also deforms the pilehead leaving less energy available for theuseful purpose of driving a pile.

The energy of a diesel hammer isdeveloped by a combination of the falling

of the ram, compression of the air in thecombustion chamber, and the firing of thediesel fuel. This combination eliminates

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the need for a heavy ram at a low velocityand depends only on sufficient energy toproperly move the pile.

With air or steam hammers, a double-acting or differential-acting hammer ispreferred when piles must be driven to

considerable depth where penetration per blow is small. The greater frequency of blows give faster penetration.

The simple-acting hammer can be usedwhere the soil above the bearing stratumcan be penetrated rapidly under easydriving conditions.

For driving precast concrete piles, aheavy ram with low impact velocity isrecommended. When driving is easy,hammer blows should be minimized untilresistance develops. This may avoid stresswaves that might cause cracking.

3-14. Equipment assembly.

Skill and caution are required in the erectionof pile-driving equipment. Assembly in-formation is not within the scope of thismanual. For comprehensive assembly in-structions, consult the operator’s manual forthe pile-driving equipment to be used.

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C H A P T E R 4

PILE INSTALLATION

Section I. PREPARATION OF PILESFOR DRIVING

4-1. Preparation of timber piles.

Timber piles selected for a structure should belong enough so that the butts are 2 or 3 feethigher than the finished elevation after thepiles are driven to the desired penetration.(Methods of predetermining pile lengths aredescribed in chapter 5.) Timber piles requirelittle preparation or special handling;however, they are susceptible to damageduring driving, particularly under harddriving conditions. To protect the pile againstdamage, the following precautions should betaken.

a. Fresh heading. When hard driving isexpected, the pile should be fresh headed byremoving 2 to 6 inches of the butt. Removinga short end section allows the hammer totransmit energy more readily to the lowersections of the piles. Butts of piles that have

been fresh headed should be field treatedwith creosote and coal tar pitch (chapter 8),after the pile has been driven to the desiredpenetration.

OPERATIONS

b. Fitting. Proper fit between the butt of thepile and the driving cap of the hammer is themost important factor in protecting the pile

from damage during hard driving. The buttof the pile must be square cut, shaped to fitthe contour of the driving cap, and a littlelarger than the dimensions of the cap so thewood will be compressed into the driving cap.Under most driving conditions the tip of atimber pile should be left square withoutpointing. The following points should be keptin mind when fitting timber piles.

Pointing timber piles does little to in-crease the rate of penetration.

Piles with square tips are more easilykept in line during driving and provide better end bearing.

For very hard driving, steel shoes protectthe tips of piles (figure 4-1, 1). Steel platesnailed to blunt tips (figure 4-1, 2) offerexcellent protection.

c. Wrapping. If a driving cap is not used, orif crushing or splitting of the pile occurs, thetop end of the pile should be wrapped tightlywith 12-gage steel wire to forma 4-inch band.The steel wire should be stapled firmly in

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place. This is a simple method of protectingpile butte during hard driving. Steel strappingabout 1¼ inches wide will also provideadequate protection. Strapping should en-circle the pile twice, be tensioned as tightly aspossible, and be located approximately twofeet from the butt.

d. Splicing. Piles can be spliced if singlesections of the required length are notavailable or if long sections cannot behandled by available pile drivers. Generally,

decreasing pile spacing or increasing thenumber of piles is preferable to splicing.Except in very soft soils or in water, thediameter of the complete splice should not begreater than the diameter of the pile (figure4-2). The ends of the piles must be squared,and the diameter trimmed to fit snugly in the8-inch or 10-inch steel pipe. Steel splice platesare also used (figure 4-2).

e. Lagging. Lagging a friction pile with steelor timber plates, planks, or rope wrapping

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can be used to increase the pile’s load-carryingcapabilities.

4-2. Preparation of steel piles.

a. Reinforcing. Point reinforcement isseldom needed for H-piles; however, if drivingis hard and the overburden contains ob-

structions, boulders, or coarse gravels, theflanges are likely to be damaged and the piles

may twist or bend. In such cases H-piles(figure 4-3) and pipe piles (figure 4-4) should

be reinforced.

b. Cleaning. Pipe piles driven open-ended,must be cleaned out before they are filledwith concrete. Ordinarily they are closedat the lower end, usually with a flat plate

(figure 4-4). In a few soils, such as stiff plasticclays, the overhang of the plate should be

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eliminated. Such pipe piles can be inspectedafter driving. Damaged piles should be iden-tified and rejected if not repairable.

c. Splicing. H-piles can be spliced anddesigned to develop the full strength of thepile both in bearing and bending. This isdone most economically with butt-weldedsplices (figure 4-5). This method requires that

the pile be turned over several times during

the welding operation. Various types of plateand sleeve splices can be used (figure 4-6).Splicing is often performed before the pilesare placed in the leads so pile-drivingoperations are not delayed.

d. Lagging. Lagging is of questionable valueand if attached near the bottom of the pile,will actually reduce the capacity of the pile.

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4-3. Preparation of concrete piles.

Precast concrete piles should be straight andnot cambered by uneven prestress or poorconcrete placement during casting.

a. Reinforcing. Reinforcing of precastconcrete piles is done in the manufacturing.The top of the pile must be square orperpendicular to the longitudinal axis of thepile. The ends of prestressing or reinforcingsteel should be cut flush with the end of thepile head to prevent direct loading by the ramstroke. Poured concrete piles may be re-inforced with steel reinforcing rods.

b. Splicing or cutting. Precast concretepiles are seldom, if ever, spliced. If the drivinglength has been underestimated, the pile can be extended only with considerable difficulty.The piles are expensive to cut if the length

has been over estimated. Poured concretepiles should not require splicing as length ispredetermined in the planning stages.

Section II. CONSTRUCTIONPROCEDURES

4-4. Positioning piles.

When piles are driven on land, for example a building foundation, the position of each pilemust be carefully established, using availablesurveying equipment. A simple template can

be constructed to insure proper positioning of the piles. Piles generally should not be drivenmore than three inches from their designlocation. Greater tolerances are allowed forpiles driven in water and for batter piles.

4-6. General driving procedures.

Piles are set and driven in four basic steps(figure 4-7).

a. Positioning. The pile driver is broughtinto position with the hammer and cap at the

top of the leads (figure 4-7, 1).

4-8

b. Lashing. Generally, the pile line is lashedabout one third of the distance from the top of the pile, the pile is swung into the helmet, andthe tip is positioned into the leads (figure 4-7,2). A member of the handling crew can climbthe leads and, using a tugline, help align thepile in the leads.

c. Centering. The pile is centered under thepile cap, and the pile cap and hammer arelowered to the top of the pile. If a drophammer is used, the cap is unhooked from thehammer (figure 4-7, 3).

d. Driving. The hammer is raised anddropped to drive the pile (figure4-7, 4). Drivingshould be started slowly, raising the hammeronly a few inches until the pile is firmly set.The height of fall is increased gradually to amaximum of 6 feet. Blows should be appliedas rapidly as possible to keep the pile moving.

Repeated long drops should be avoided sincethey tend to damage the top of the pile.

4-6. Driving requirements.

Careful watch must be kept during driving toavoid damage to the pile, pile hammer, or

both. Precautions and danger signs includethe following

a. Support. The pile driver must be securelysupported, guyed, or otherwise fastened toprevent movement during driving.

b. Refusal. Refusal is reached when theenergy of the hammer blow no longer causespenetration. At this point, the pile has reachedrock or its required embedment in the bearingstratum. It is not always necessary to drivepiles to refusal. Friction piles frequently must

be driven only far enough to develop thedesired load bearing capacity. In certaintypes of soils, such as a very soft organic soilor deep marsh deposit, a considerable lengthof pile may be necessary to develop adequateload capacity. Driving in such soils is

frequently easy as piles may penetrate several


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feet under a single hammer blow. It isimportant that driving be a continuousprocedure. An interruption of even severalminutes can cause a condition of temporaryrefusal in some types of soils, thus requiringmany blows to get the pile moving again.

c. Timber piles. Timber piles are frequentlyoverdriven when they are driven to end bearing on rock (figure 4-3). If the pile hits afirm stratum, depth may be checked bydriving other piles nearby. If the piles stop atthe same elevation, indications are that afirm stratum has been reached. Followingare items to be watched for when drivingtimber piles.

(1) Breaking or splitting below ground.If the driving suddenly becomes easier, or if the pile suddenly changes direction, thepile has probably broken or split. Furtherdriving is useless as bearing capacity isunreliable. Anew pile must be driven closeto the broken one, or the broken one pulledand a new one driven in its place.

(2) Pile spring or hammer bounce. The pilemay spring or the hammer may bouncewhen the hammer is too light. This usuallyoccurs when the butt of the pile has beencrushed or broomed, when the pile has metan obstruction, or when it has penetrated

to a solid footing.(3) Double-acting hammer bounce. When adouble-acting hammer is being used, toomuch steam or air pressure may cause

bouncing. When using a closed-ended dieselhammer, lifting of the hammer on theupstroke of the ram piston can cause

bouncing. This is caused by too high athrottle setting or too small a hammer.Throttle controls should be backed off justenough to avoid this lifting action.

(4) Crushed or broomed butt. If the butt of atimber pile has been crushed or broomed

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for approximately 1 inch, it should be cut back to sound wood before driving iscontinued. There should be no more thanthree or four final blows per inch for timberpiles driven with a diesel, steam, or airhammer. Further driving may fracture thepile or cause brooming.

d. Steel piles. In driving steel piles, par-ticular care must be taken to see that thehammer strikes the top of the pile squarely,with the center of the hammer directly overthe center of the pile. Watch for the following.

(1) Slack lines. A hammer suspended froma slack line may buckle the top section andrequire the pile be trimmed with a torch before driving can proceed. Driving caps(previously described) will prevent thistype of damage to H-piles.

(2) Alignment. When a steel pile is drivenwith a flying hammer (free-swing hammer),the pile should be aligned with guys (figure4-9). Hooks, shackles, or cable slings can be used to attach guy lines. A pile should beconsidered driven to refusal when five

blows of an adequate hammer are requiredto produce a total penetration of ¼ inch orless.

e. Concrete piles. Required driving re-sistances for prestressed concrete piles areessentially the same as for steel piles. Drivingstresses should be reduced to prevent piledamage. The ram velocity or stroke should bereduced during initial driving when soilresistance is low. Particular attention should be paid to the following.

(1) Cap or helmet. The pile-driving cap orhelmet should fit loosely around the piletop so the pile may rotate slightly without binding within the driving head.

(2) Cushioning. An adequate cushioning

material must be provided between thehelmet or driving cap and the pile head.


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Three or four inches of wood cushioningmaterial (green oak, gum, pine, or firplywood) are adequate for piles less than50 feet in length in a reasonably good

bearing stratum. Cushions 6 inches thick

or more may be required when drivinglonger piles in very soft soil. The cushionshould be placed with the grain parallel tothe end of the pile. When the cushion becomes highly compressed, charred, or burned, it should be replaced. If driving ishard, the cushion may have to be replacedseveral times during the driving of a singlepile.

f. Special problems. Special problems mayarise when driving various types of piles. Alist of potential problems, with possible

methods of treatment, is shown in table 4-1.

4-7. Aligning piles.

Piles should be straightened as soon as anymisalignment is noticed during the driving.When vertical piles are driven using fixed

leads, plumbing is not a matter of concernsince the leads will hold the pile and correctthe alignment. Vertical piles normally shouldnot vary more than 2 percent from the plumbposition.

a. Checking misalignment. Along mason’slevel is useful in plum bing the leads. For

batter piles (figure 4-10) a plywood templatecan be used with the level. Exact positioningis easier if the driver is provided with aspotter or moon beam.

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b. Checking misalignment by cap re- alignment. The alignment can be checked bymoval. If the pile is more than a few inches lifting the cap from the pile butt. The pile willout of plumb during driving, an effort should rebound laterally if not properly aligned with

be made to restore the pile to its proper the leads and hammer.

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c. Aligning with block and tackle. Duringdriving, a pile may be brought into proper

H-piles, this procedure may induce un-desirable twisting and should be avoided if

alignment by using block and tackle (figure4-11). The impact of the hammer will tend to

possible. Jetting either alone or with thepreceding method, may be used.

jar the pile back into line. In the case of steel

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4-8. Obstructions.

Obstructions below the ground surface areoften encountered during pile-drivingoperations. Obstructions may result fromfilling operations in the area or from oldstumps or tree trunks buried by later deposits.Obstructions are frequently encounteredwhen piles are driven in industrial andcommercial areas of older cities or alongwaterfronts. They are a matter of concernsince they can prevent a pile from penetratingenough to provide adequate load-carryingcapacity. Piles are frequently forced out of line by obstructions and may be badlydamaged by continued driving in an effort to

break through the obstruction.

a. Driving. When an obstruction such as arotten log or timber is encountered, 10 or 15

extra blows of the hammer may cause the pileto breakthrough (figure 4-12, 1). With steel orprecast concrete bearing piles, extra blows of the hammer may break or dislodge a boulder(figure 4-12, 2); however, care must be takenthat blows do not damage the pile. Pilealignment should be watched carefully duringthis operation to insure that the lower portionof the pile is not being deflected out of line.

b. Using explosives. If the obstructioncannot be breached by driving, the pile should

be withdrawn and an explosive charge

lowered to the bottom of the hole to blast theobstruction out of the way (figure 4-12, 3). If using explosives is not practical, the pile can be left in place, and the foundation plan can be changed to use other piles.

c. Jetting. Jetting is particularly valuable insoils which will settle firmly around the pile.Sands, silty sands, and some gravels provideconditions suitable for jetting as drivingthrough these materials in a dense stateresults in pile damage. Displacement piles incohesionless soils are frequently placed by

jetting.

(1) Hose and pipe jetting. Jetting isperformed by inserting the jet pipe to thedesired depth, forcing water through thepile to loosen the soil, then dropping thepile into the jetted hole and driving the pileto its resistance. If the pile freezes beforefinal embedment, jetting can be resumed.

Jetting should not be deeper than 4 or 5 feetabove final grade.

(2) Attached jetting pipes and hoses. Jetting for timber, steel, or standardprecast concrete piles is usually done by anarrangement of jetting pipes and hoses.The jet pipe is connected with a flexiblehose and hung from the boom or the piledriver leads. When possible, two jet pipesare lashed to opposite sides of the pile.Usually the pile is placed into positionwith the hammer resting on it to give

increased weight, and the jet is operated sothat the soil is loosened and displacedevenly from under the tip of the pile (figure4-13). A single jet, however, is not workedup and down along the side of the pile, asthe pile will drift in that direction. Properuse of jet pipes is shown in figure 4-14.

(3) Special precast concrete jetting. Tofacilitate jetting, jet pipes can be embeddedinto precast concrete piles, Jetting ar-rangements for precast concrete piles areshown in figure 4-15.

(4) Precautions. Where piles must be drivento great depths, the double water jets may be insufficient. Additional compressed aircan be effective. For combined water andair jetting, the simplest method is to tack-weld a small air pipe to the outside of thewater-jet pipe. In any jetting operation, thealignment of the pile is critical. Jetting is auseful method to correct the alignment of timber piles in a pile bent (figure 4-16).

Jetting around a pile while it is beingdriven is undesirable as the pile will drift

off line and location. Pile tips must be well

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seated with reasonable soil resistance 4-9. Predrilling. before full driving energy is used. Theultimate bearing capacity of the pile is It may be necessary to predrill pilot holes if generally not significantly affected by the soils above the bearing stratum are

jetting. However, jetting will greatly re- unusually stiff or hard. Predrilling keeps theduce the uplift capacity of a pile. preservative shell of treated timber piles

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intact. Predrilling also reduces underwaterheave and lateral displacement of previouslydriven adjacent piles. Holes are drilledslightly smaller than the diameter of the pileand to within a few feet of the bearingstratum. The pile is inserted, and the weightof the hammer forces the pile down near the bottom of the drill hole displacing any slurry.

The pile is then driven to the requiredpenetration or resistance.

a. Rotary equipment. Predrilling should bedone with wet rotary equipment which leavesthe hole filled with a slurry of mud. Themethod employs a fishtail bit that contains awater jet within the drill stem. The water anddrill cuttings form a slurry which lines thewalls and stops sloughing of unstable soillayers. Additives (such as bentonite) can also

be used to stabilize the walls of the drill hole.

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b. Augers. Augers which remove all materialfrom the hole can cause a quicksand action.Sand or soil may flow into the drilled hole below the water table. Augers should be usedonly above groundwater tables and in soilswhere a drill hole will stand open withoutcollapsing.

4-10. Special placement techniques.

a. Spudding. Spuds can penetrate debris orhard strata so the pile can reach the bearingstratum. Spuds consist of heavy pile sections,usually with special end reinforcement. Whenheavy piles (such as steel or precast concretepiles) are driven, the pile may be raised anddropped to break through a layer of hardmaterial or an obstruction. In a similaroperation, a pilot pile is withdrawn, and thefinal pile is driven in the hole.

b. Jacking. A pile may be jacked intoposition. This method is usually used when itis necessary to underpin the foundation of astructure and headroom is limited or whenvibration from conventional driving coulddamage an existing structure. The pile is

jacked in sections using a mechanical orhydraulic screw jack reacting against theweight of the structure. The pile is selected forthe specific situation, and it is built up inshort, convenient lengths.

c. Vibrating. High-amplitude vibrators areused for driving piles in saturated sand andgravels, Vibratory hammers are particularlyadvantageous for driving sheet piling.

4-11. Driving piles in water.

a. Positioning piles. When piles are drivenin water, different methods may mark thedesired pile positions. When a number of bents are to be constructed, a stake is placedat each abutment approximately 6 inches

from the pile centerline (figure 4-17). A wirerope is stretched between the two stakes, and

a piece of tape or cable clip is fastened to therope at each pile bent position. Piles are thendriven at each tape or cable clip.

b. Using floating pile drivers. When afloating pile driver is used, a frame forpositioning piles may be fastened to the hull.

A floating template is sometimes used toposition piles in each bent (figure 4-18).Battens are spaced along the centerlinedesired for each pile. The battens are placedfar enough apart so that, as the pile is driven,the larger-diameter butt end will not bind onthe template and carry it underwater. If thepiles are driven under tidal water, a chain orcollar permits the template to rise and fallwith the tide. If the ends of the battens arehinged and brought up vertically, thetemplate may be withdrawn from betweenthe bents and floated into position for the

next bent provided the pile spacing is uniform.

c. Using floating rigs. If a floating rig isavailable, it can be used to drive the piles foran entire structure before the rest of the work.In general, more piles can be driven per man-hour with floating equipment because thedriver is easily moved. As soon as the piles inone bent have been driven, the rig may bepositioned to drive the next bent, while the bent just driven is braced and capped.Floating pile. driver rigs are difficult toposition where currents are strong andadequate winches are unavailable. Otherwise,they can be positioned easily either end-on orside-on to the pile bent which is being driven.Batter piles can be driven in any desireddirection by adjusting the spotter or catwalk,without using a moon beam.

d. Driving from bridge or wharf. Whenpile driving uses mobile equipment operatingfrom a deck of a bridge wall structure, twoprocedures may be used in moving the piledriver forward.

(1) Walking stringer method. As each bentis driven, the piles are aligned, braced, cut,

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and capped. The movable stringers aremade by placing spacer blocks betweentwo or three ordinary stringers so thedriving rig can advance into position todrive the next bent. The movable stringersare laid onto the bent which has just beencompleted. When the advance row or rowsof piles have been braced, cut, or capped,the pile driver picks up the temporarystringers behind and slings them into placeahead. The installation of permanentstringers and decking follows behind thepile driver. Variations of this method arepossible when a skid-mounted piledriver isused. This method gives the pile driv

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FM 5-134 Pile Construction - ARMY