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EM 1110.2.2504 31 Mar 94 2-3, Geotechnical Considerations Because sheel pile walls derive !heir support from Ihe surrounding soil. an investigation of !he foundation materials along Ihe wall aIignmenl should be conducted aI !he inception of Ihe planning for Ihe wall. This investigation should be a cooperative effort among Ihe sttuclUral and geoleClulical engineers and should include an engineering geologist familiar wilh Ihe area. AII existing daIa bases should be reviewed. The goals of Ihe initial geoleChnical survey should be to identify any poor foundation conditions which mighl render a waIl no! feasible or require revision of Ihe wall aIignmenl. to identify subsurface conditions which would impede pile driving. and to plan more delailed exploration required to derme design paramelelS of !he syslem. GeoleChnical investigation requirements are discussed in delail in Chapler 3 of Ibis EM. 2-4. Structural Considerations a. Wall type. The selection of Ihe Iype of wall. anchored or cantilever, musl be based on Ihe function of the waIl. !he characleristics of Ihe foundation soils. and the proximily of Ihe waIl to existing sttuclures. (1) Cantilever waIls. Cantilever walls are usually used as l100dwall or as eaJ1h retaining walls wilh low waIl heights (10 to 15 feet or less). Because cantilever waIls derive Iheir support solely from Ihe foundation soils. Ihey may be insla!led in relatively close proximity (bUI not less Ihan 1.5 times Ihe overall lenglh of Ihe piling) to existing stnJctures. Typical cantilever wall configll11llions are shown in Figure 2-1. (2) Anchored waIls. An anchored wall is required when Ihe heighl of the wall exceeds the heighl suilable for a cantilever or when Ia1eraI deflections are a consid- eration. The proximity of an anchored wall to an exist- ing structure is governed by !he horiwntaI distance required for instaIIation of the anchor (Chapler 5), Typical configurations of anchored waIl systems are shown in Figure 2-2, b. Materials. The designer must consider Ihe possi- bility of material delerioration and ilS effect on Ihe sttuclural integrity of the system. Masl permanenl sttuctures are consttucted of steel or concrete. ConCrele is capable of providing a long service life under normal circumstances but bas relatively high initial costs when compared to stee1 sheel piling. They are more difficull to instaIllhan steel piling, Long-1em1 field observations indicate IhaI steel sheel piling provides a long service 2-2 life when properly designed. Permanenl insla!lations should allow for subsequenl insla!lation of cathodic proleCtion should excessive corrosion occur. . (I) Heavy-gauge steel. Steel is !he most common material used for sheel pile walls due to ils inherenl sttenglh. relative light weighl. and long service life. These piles consist of inlerlocking sheets manufactured by eilher a hol-rolled or cold-formed process and con- form 10 Ihe requiremenls of Ihe American Sociely for Testing and Materials (ASTM) Standards A 328 (ASTM 1989a). A 572 (ASTM 1988). or A 690 (ASTM 1989b). Piling conforming to A 328 are suilable for mosl inslaI- lations. Steel sheel piles are available in a variety of standard cross sections. The Z-Iype piling is predomi- nanlly used in relaining and l100dwall applications where bending sttenglh governs Ihe design. When inlerlock tension is Ihe primary consideration for design, an arched or straighl web piling should be used. Turns in Ihe wall aIignmenl can be made wilh standard bent or fabricated comers. The use of steel sheel piling should be considered for any sheel pile stnJcture. Typical configmations are shown in Figure 2-3. " (2) Light-gauge steel. Lighl-gauge steel piling are shallow-deplh sections. cold formed to a constanl Ihick- ness of less Ihan 0.25 inch and manufactured in accor- dance wilh ASTM A 857 (1989c). Yield strength is dependent on Ihe gauge Ihickness and varies between 2S and 36 kips per square inch (ksi). These sections have low-section moduli and very low momenls of inertia in comparison to heavy-gauge Z-sections. Specialized coatings such as hol dip galvanized, zinc plated. and aluminized steel are available for improved corrosion resistance. Lighl-gauge piling should be considered for Iemporary or minor structures. Lighl-gauge piling can be considered for permanent consttuction when accom- panied by a deIaiIed corrosion investigation. Field IeSIS should minimally include PH and resistivity measure- ments. See Figure 2-4 for typical lighl-gauge sections. e) (3) Wood. Wood sheet pile walls can be conslrUcted of independenl or tongue-and-groove interlocking wood sheets. This type of piling should be restricted to short- to-moderale wall heights and used only for Iemporary struClures. See Figure 2-5 for typical wood sections. (4) Conaele. These piles are precast sheets 6 to 12 inches deep, 30 to 48 inches wide. and provided wilh tongue-and-groove or grouted joints. The grouted-Iype joinl is cleaned and grouted afler driving to provide a reasonably walertighl waIl. A bevel across the pile boItom. in !he direction of pile progress. forces one pile e)