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<br />. <br /> <br />". <br /> <br />. <br /> <br />. <br /> <br /> <br />GROUND SURFACE <br />//I.&W/~ <br /> <br />SHEET PILE <br /> <br />PLASTIC HINGE <br /> <br />a. Cantilever wall <br /> <br />Figure 5-3, Flexural fellure of aheet piling <br /> <br />and duration of loading. and !he performance of the wall <br />should be carefully monilOred 10 prevent pelTllllllCnl <br />damage. Lower factors of safely or higher maleria1 <br />stresses may be used for these conditions with, the inlenl <br />that the system should experience no more than <br />cosmetic damage. <br /> <br />(3) Exlrenle conditions. A worst-case scenario <br />representing !he widesl deviation from the usual loading <br />condition should be used 10 assess !he loads for this <br />case. The design should allow the system 10 sustain <br />these loads withoul experiencing catasIrophic collapse <br />but with the acceplance of possible major damage which <br />requires rehabilitation or replacement To conttast usual <br />and exlrenle conditions. the effeclS of a hlDTicane on a <br />burricane prolection wall would be the "usual" condition' <br />governing the design. wbile the 10ads of !he same burri. <br />cane on an embankment relaining wall would be <br />"extreme." <br /> <br />d. Factors of safety for SlDbility. A variely of <br />methods for introducing "factors of safety" inlO the <br />design process have been proposed; bowever. no <br />univenal procedure bas emerged. In genml. the design <br />should conlain a degree of conservatism consislenl with <br /> <br />EM 111 ().2.2504 <br />31 Mar 94 <br /> <br /> <br />'" , <br /> <br />. <br /> <br />SHEET PILE <br /> <br />TIE ROD <br /> <br />. . <br />'. <br /> <br /> <br />ANCHOR <br /> <br /> <br />PLAS TIC HINGE <br /> <br /> <br />b. Anchored wall <br /> <br />the experience of !he designer and !he reliabi1ily of !he <br />values assigned 10 the various system paramelelli. A <br />procedure which bas gained acceplance in the Corps of <br />Engineers is 10 apply a factor of safely (strength reduc- <br />tion factor) 10 the soil SlJ'ength paramelerS . and c wbile <br />using "bes! estimaleS" for other quantities. Because <br />passive pressures ca1cu1aled by the procedures described <br />in ChapIer 4 are less likely 10 be fully developed than <br />active pressures on the relaining side. the currenl <br />practice is 10 evaluale passive pressures using "effec- <br />tive" values o~ . and c given by <br /> <br />1an('.If) . Ian(') I FSP <br /> <br />(5-1) <br /> <br />and <br /> <br />C.1f . C I FSP <br /> <br />(5-2) <br /> <br />where <br /> <br />FSP = factor of safely for passive pressures <br /> <br />5-3 <br />