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

b. Deliberate construction. In a theater ofoperations, 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 thefoundation 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 pilefoundations, 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 treatedsote (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 factors are discussed in chapters 5through 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, andmarine 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 cutoff if they do not penetrate as far as esti-mated. Piles driven into water substrata canbe 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 shipbecause they are relatively light and strong.Because they float, they can be transportedby 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

2-12. Classification.

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

a. Resilience. A steel pile is not as resilientas a timber pile; nevertheless, it is strong andelastic. Large lateral loads may causeoverstressing and permanent deformation ofthe steel, although the pile probably will notbreak. 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 willcreases 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 smallboulders are encountered during driving,they may be broken by a chopping bit orblasting. 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. Fulluse 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 ofpermitting 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 strengthwith 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 ofgreat concern in military structures, steelbearing 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.

2-17. Shipping and handling.

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 mechanicaldamages.

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

2-18. Classification.

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 ifthe piles are prestressed. Classification isbasically 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. Theyare 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 castingyard 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 toprevent 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 oilbefore use.

b. Reinforcement. For precast concrete pilessubjected to axial loadings, steel rein-forcement provides resistance to the stressescaused by handling and driving. Threemethods of handling concrete piles areillustrated in figure 2-6. Depending on themethod used, the size and number oflongitudinal 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 concretemixes 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, orburlap give good results. The piles should notbe moved or driven until they have acquiredsufficient strength to prevent damage. Eachpile 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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2-24. Shipping and handling.

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

Section V. CAST-IN-PLACE PILES

2-25. Classification.

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

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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 providegreater 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 ofinstallation. Even small inflow quantities ofwater 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 theyare 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 whenbraced 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. Forexample, 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 longshorecurrents 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. Sheetpiling 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, shouldbe 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 grooveand 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 centersbetween the bolts hold the planks together.When bolts are not used, the spikes shouldbe 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 oppositeside 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 planksare 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 whenbe 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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