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~~JJ TAII B~~LE 4: FACTOR OF SAFETY FORMULAS <br />`I x r Ccntre of rotition . <br />-~~Tension crack <br />_ ~Phreatic <br />~~ surface <br />R <br />i <br />Y ~' T <br />X /. ~Trzz z/7 <br />I I ', ~~ ~~.:' <br />Typical slice <br />Failure through toe of slope <br />• <br /> <br />Hote An61e p !a neaat ive nc~n <br />sl iding !s uphill. <br />Factor of Safety y: <br />L X/(1 • Y/F) <br />F <br />F2 ~ . Q <br />where <br />_ ~ ~c' • ~ yh ' 7rM.) Tan ~' ~ ex/Cosa <br />Y ~ Tan a Tan ~' <br />2 ~ yh dt Sina <br />• Q ~ f7„ z2 4/p , <br />The fol loving conditions must be satisfied (or each slice <br />_ c' Tan a/ <br />I • Y/F <br />- 2) Cos a ~ 1 • Y/F~ > 0.2 . <br />• Figure 112: lishop's slmpli(ied mcthod of slices for analysis of circular <br />failure in slopes cut into materials in which (allure is <br />deli ned by the Ybhr-Coulomb failure criterion. <br />• <br />FROM. ROCK SLOPE ENGINEERING, CHAPTER 9 '"CLRCULAR FAILURE" <br />REVISED THIRD EDITION, PAGE 248. <br />Revised 3/82 3.56-5 <br />