pile - chapter 2

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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 ph ysical prop erties 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 d ictateconstruction.

b. Deliberate construction. In a theater ofoperations, timber piles are normally avail-able in leng ths of 30 to 70 feet. They a re 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 u sed for a longtime. Small displacement steel H-piles are

particularly suited to penetrating deep layersof cour se gravel, boulders, or soft rock such ascoral. Such p iles also reduce heave of adjacent

structures.

2-2. Arm y Facilities Comp onen tsSystem (AFCS) m aterials.

Com plete 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 p ile

founda tions, consult TM 5-301 and TM 5-302.

Section II. TIMBER PILES

2-3. Classification .

The American Society for Testing andMaterials (ASTM) classifies timber pilesaccord ing 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 p re-

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

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

(1) Type I. Type I piles, pressure treatedw ith waterborne p reservatives and creo- (3) Type III. Type III piles, pressure treated

sote (dual treatm ent), are suitable for u se with creosote, are suitable for use in marinein marine w aters of extreme borer hazard. waters of moderate borer hazard.

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b. Nonm arine use.

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

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

2-4. Ch aracter istics.

A good timber p ile has the followingcharacteristics.

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

A straight core between the butt an d tipwithin the bod y of the pile.

Uniform tap er from bu tt to tip.

2-5. Source.

Usually, timber piles are straight tree trun kscut off above grou nd swell, with branchesclosely trim m ed and bark remov ed (figure2-l). Occasionally, sawed timber may be usedas bearing piles.

2-6. Strength.

The allowable load on tim ber piles is basedon pile size, allowable working stress, soilconditions, and available driving equipment.These factors 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 intab le 2-2.

2-7. D u rability.

A p rincipal d isad vantage of timber p iles islack of d urab ility un der certain conditions.Piles are subject to fungi (decay), insects, and

m arine borers. Design life dep end s 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. Availab ility.

Timber suitable for piling is abundant inmany parts of the world (see appendix).Tim ber piling m ay be obtained from localstocks or cut from standing timber. Thenative stock may be used untreated, or apreservative may be app lied as d iscussed 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. Oth er p rop erties.

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 su bstrata 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, and

spring back into position absorbing the shockof a docking ship or oth er impact.

c. Fire susceptib ility. Timber piles ex-tending above the w ater line, as in tr estles orwaterfront stru ctures, are susceptible todamage or destruction by fire.

2-11. Shipp ing an d han dling.

Timber p iles are easy to hand le and shipbecause th ey are relatively light and strong.Because they float, they can be tra nsp ortedby rafting particularly for waterfront struc-tures. They can be pu lled, cleaned, and reusedfor supplementary construction such as false-work, trestles, and work platforms.

Section III. STEEL PILES

2-12. Cla ssifi cation .

Steel piles are u sua lly 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 pou nd s per linear foot are usedmost frequently in military construction.

a. H-piles. Steel H-piles are widely usedwh en conditions call for har d driving, great

lengths, or high w orking loads p er pile. Theypenetrate into the ground m ore readily thanother types, partly because they d isplacerelatively 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 p iles. Pipe piles are either w elded orseamless steel pipes wh ich m ay be d rivenopen-ended or closed-ended.

c. Railroad-rail piles. Railroad rails can beformed into p iles as shown in figure 2-2. Thisis useful w hen oth er sources of piles are notavailable.

d. Other. Stru ctured steel such as I-beam s,channels, and steel pipe are often availablefrom cap tured , salvaged , or local sources.With resourceful d esign and installation, theycan be u sed as piles when other, moreconventional piles are not available.

2-13.Characteristicsa. Resilience. A steel p ile is not as resilientas a timber pile; nevertheless, it is strong andelastic. Large lateral loads m ay causeoverstressing and perm anent deformation ofthe steel, although th e pile probably w ill 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 genera lly will

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be greater than the driving resistance pile and be carried dow n w ith it. The coreindicates because the skin friction in- of soil trapped on each side of the web w ill

creases after rest. In stiffer clays, th e p ile cause the pile to act as a large displacementmay h ave the soil comp acted betw een the pile.flanges in d riving. The clay m ay grip the

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(2) Pipe piles. Pipe piles driven open -endperm it greater d riving d epths, as less soildisplacement occurs. Pipe piles can bereadily inspected after d riving. If smallboulders are encountered during driving,they m ay be broken by a chopp ing bit or

blasting. Pipe piles are often filled withconcrete after dr iving.

2-14. Sou rce.

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

b. Local supp ly. In combat, piles or materialto construct them can be obtained fromcaptured enem y stock or from the localeconom y w ithin a theater of operations. Full

use should be mad e of such captu red,salvaged, or local materials by substitutingthem for the stand ard steel bearing pilingindicated by AFCS. Old or new rail sectionsmay be available from military supplychannels, captu red stocks, or un used 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, thu slengths to be hand led.

Lengths up to 100 feet are not uncom mon ,although piles greater than 60 feet requirecareful h and ling to avoid excessive bend ingstresses. Pipe p iles are somew hat stiffer thanrolled steel sections. The allowable load onsteel piles is based on the cross-sectionalarea, the a llowable w orking stress, soilconditions, and available driving equipment.The maximum allowable stress is generallytaken as 0.35 to 0.50 times the y ield streng th

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

2-16. Du rab ility.

Although deterioration is not a matter ofgreat concern in military structures, steelbearing p iles are subject to corrosion anddeterioration. The effects of corrosion,

preventive m easures taken to p rotect steelpiles, and remedial measures to correctprevious damage are discussed in chapter 8.

2-17. Shippin g and hand ling.

a. Transp orting. Although quite heavy,steel piles are easy to hand le and ship. Theycan be transp orted by rail, water, or truck.Precautions should be taken during shippingand hand ling to prevent kinking of flanges orperm anent d eformation. Steel pipes m ust beprop erly stored to p revent mechanical

damages.

b. Lifting and stackin g. 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 on e fifthto one fourth of the length from each end toequ alize the stress. To mak e lifting easier, asmall hole may be burned in a flange betweenthe up per third and quarter points. Then ashackle may be attached to lift the p iles intothe leads. Piles should be stacked on timbersso that they are kept r easonably straight.

Section IV. PRECAST CON CRETEPILES

2-18. Classifi cation .

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 isbasically by shape and is covered inparagr aph 2-20.

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2-19. Ch aracter istics. difficulty requiring both the chiseling of theconcrete and the cutting of the reinforcing

Precast piles are strong, du rable and m ay be rods.cast to the designed sh ape for the p articularapplication. The process of precasting is not 2-20. Sou rce.ava ilable in the theater of opera tions. They

are d ifficult to han dle u nless prestressed, and Precast concrete p iles are m anu factured 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 yardinclud es 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 han dled bywheelbarrows or buggies. Additional storagespace may be need ed for the completed p iles.

a. Form s. Forms for piles ma y be of wood(figure 2-5) or meta l. They m ust b e 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. Reinforcemen t. For pr ecast concrete p ilessubjected to axial loadings, steel rein-forcement p rovid es resistance to the stresses

caused by hand ling and driving. Threemethods of handling concrete piles areillustrated in figure 2-6. Depend ing on themethod used, the size and num ber oflongitudinal reinforcement bars aredeterm ined from d esign charts in figu re 2-7.These charts are based upon an allowablestress of 1,400 psi in the con crete and 20,000psi in the steel, without allowan ce for imp act.Minimum reinforcement cages are assembledas shown in figure 2-4. Adequate spiralreinforcing at th e pile head and tip isnecessary to red uce the tend ency of the pile tosplit or span d uring d riving.

c. Placemen t. 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 ha ving a l-inch to 2-inchslump with concrete vibrators. Reinforcementshould be properly positioned and securedw hile the concrete is placed an d v ibrated.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 pilesmu st be kept wet for at least seven d ays whenregular portland cemen t 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 p iles should n otbe moved or driven until they have acquiredsufficient strength to prevent damage. Each

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

2-21. Strength.

Precast concrete piles can be driven to highresistance without damage. They are as-signed greater allowable load s than timberpiles. As with other pile types, allowableloads are based on the pile size, soilconditions, and other factors. Customaryallowab le 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. Du rab ility.

Und er ordinary conditions, concrete piles arenot subject to deterioration. They can be usedabove the water table. Refer to chapter 8 foradd itional informa tion on du rability.

2-23. Availability.

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

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2-24. Shippin g and han dling.

a. Han dling. Piles should be handled inaccordance with the p rocedure selected fordesign (figure 2-6). For placement, piles maybe lifted b y cables and hooks looped aroun dthe 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 arr angem ent.

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 m ust be taken inlifting the pile so that tension in the cables

is equal; otherw ise, the entire load m ayrest on one end.

When th e pile is raised to a vert icalposition, another line, CD, is attached.When draw n up , the sheave at A shiftstoward C.

An ad ditional line is needed w ith thiscable arrangem ent to p revent the p ile fromgetting out of control when it is raised to avertical position.

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

betw een the tiers must be in ver tical lines sothat a pile in a lower tier will not be subject tobending by the w eight of the piles above. Anexamp le of imp roper stacking is show n infigu re 2-8. A forklift or sp ecially equ ipp edfront-end loader can be used to m ove pilesfrom the storage area to the w ork 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. Clas sifi cation .

Cast-in-place piles are either cased oruncased. Both are m ade a t the site by forming

a hole in the grou nd at the required locationand filling it with a p roperly d esigned con-crete mix.

a. Cased. The concrete of a cased p ile is castinside a metal casing or pipe left in thegroun d. The casing is driven to th e requireddepth and cleaned before placement ofconcrete. If the casing is relatively thin, ama nd rel is used to d rive the casing. Man ydifferent kinds of shells and m and rels areavailable commercially, but not throughmilitary supply channels. Those of foreign

man ufacture may be available in a theater ofoperation.

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b. Uncased. Uncased concrete piles referredto as d rilled p iers are frequently u sed. Variousaugers are u sed for drilling holes up to 72inches in d iameter with dep ths up to 60 feet ormore. Auger h oles are excavated by the d ryprocess. The bottom of the p ier maybe un der-reamed at the base, if desired, to provide

greater end -bearing area or resistance againstup lift forces. Drilling m ud advan cing th roughsubmerged 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 sup portenvironment. Materials for concrete con-struction are readily available in manym ilitary situations, thus d rilled p iers havesome m ilitary ap plication. They require largediam eter au gers. Installation requires betterthan average workmanship. Groundw ater isinfluential in determining the difficulty ofinstallation. Even small inflow quantities ofwater m ay indu ce caving, thus requiring theuse of casing or dr illing m ud . Drilled p ierscan provide a rapid and econom ical meth odof pile installation un der man y cond itions.

2-27. Strength and durability.

Cast-in-place piles are strong. Large loadscan be carried by cast-in-place piles dependingon t he cross-sectiona l area of th e p ile. Likepr ecast piles, cast-in-place piles are d ur able.If the pile is cased, even though the casingshould deteriorate, the concrete portion willrema in intact.

2-28. Con stru ction.

Construction of cast-in-place p iles isdescribed in chapter 4.

Section VI. SHEET PILES

2-29.Classification.

Sheet piles vary in u se and ma terials. Theym ay be classified by th eir uses. They d ifferfrom p reviously described p iles in that they

are not bearing piles, but are retaining piles.Sheet p iles are sp ecial shap es of interlockingpiles mad e of steel, w ood , or concrete wh ichform a continuou s w all 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 stru ctures, the sheetpiles depend on embedm ent supp ort, as incantilever sheet piling, or embed m ent andanchorage at or near th e top, as in an choredsheet piling.

b. Cofferdams. Cofferdam s exclud e waterand earth from an excavation to facilitateconstruction.

c. Trench sheeting. Trench sheeting w henbraced at several points is termed bracedsheeting.

d. Smal l dam s and cutoff wal ls. Sheetpiles may be u sed to form sm all dam s andmor e frequently cutoff walls beneath w ater-retaining structures to control seepagethrough the foundations.

e. Bridge piles. Sheet piles are used in th econstru ction of bridges and left in place. For

examp le, a pier may be formed by d rivingsteel sheet piling to create a circular enclosure,

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excavating th e material inside to the d esired available sizes and shapes are given indep th, and filling the enclosed space withconcrete.

f . G roins and sea walls . Sea w alls areparallel to the coastline to prevent directwav e and erosion d amage. Groins or jettiesare p erpend icular, or nearly so, to the coast-line to prevent damage from longshore

currents or tidal erosion of the shore w hen th emotion of the w ater is parallel, or at an angle,to the shoreline.

2-31. Mat erial s.

a. Steel sheet p i l ing. 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 w ater, with m odest pr otection. Sheet

piling available through military supplychann els is listed in table 2-3. Comm ercially

TM 5-312. The deep-arch web and Z-piles areused to resist large bending movements(figure 2-9). Sheet pile sections of foreignm anu factur e, either steel or concrete, shouldbe used when available. The sizes andproperties may differ app reciably from typescommonly available in the United States.

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

(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 ou ter planks form the groove

and the midd le plank forms the tongue.Three 2-inch x 12-inch or three 3-inch x12-inch planks are usually used to formeach p ile. Two bolts on 6-foot centers a ndtwo rows of spikes on 18-inch centersbetween the bolts hold the p lanks together.When bolts are not u sed, the spikes shouldbe driven in offset rows spaced 12 inchesapart.

(2) Tongue-and-groove piling. Milledtongue-and -groove p iling is lightweightand used where watertightness is not

required. If heavier timbers are available,

the tongue and tw o strips on the opp osite

side form ing the g roove. Tim ber (6-inch x12-inch) may be interlocked by cutting2-inch grooves on each side an d 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 tw o row s 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 p iling (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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pile - chapter 2

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