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<br />55 <br /> <br />-~ <br /> <br /> <br /> <br />w <br /> <br />( a ) <br /> <br />( b ) <br /> <br />Figure 6,10, Characteristics of a roti\tional slide. (Reference 6) <br /> <br />~ <br />;:::.. I I <br />.... I / <br />.............. <br />.............. I I ACTIVE <br />=r...... DIRECTION OR 1*-+/ -PRESSURE <br />SLIDE I <br />..... ......... ~ 111( -. I / <br />'L ~...v <br /> <br />PASSIVE <br />PRESSURE <br /> <br />Figure '0,11, Translatory slide, (Reference 8) <br /> <br />Figure 6.10 illustrates a cross section of a sliding soil mass along a curved surface (rotational <br />failure surface). The sliding tendency is developed b~ the moment of the mass about the <br />center of the arc as shown. This moment is opposed by the total shearing resistance <br />developed along the assumed sliding surface. Of course, when all available resistance is over- <br />come, a progressive failure occurs. <br /> <br />Various numerical procedures, most involving possi~le curved failure surfaces have been <br />proposed for evaluating the rotational slide, but a hi~h degree of accuracy in defining a <br />failure shape is inconsistent with other inherent feat\"es of the analysis (i.e., uniformity of <br />soil, number of boring samples tested, possible judg\nent in computation of angle of friction <br />or cohesion, the weight of soil, etc.) , For this reason,' the simple Swedish Slide Method or the <br />Modified Swedish Method (method of slices) among others, are acceptable analysis techni- <br />ques, Most geotechnical engineering firms have acc~ss to computer programs that call quic- <br />kly evaluate embankment stability if a detailed anal~sis is required, <br /> <br />For more detailed information relating to slope stab:ility analysis and other embankment <br />design considerations, the reader is encouraged to r<lfer to Design and Construction of <br />Levees. EM 1110-2-1913 as published by the US A~my Corps of Engineers (Reference 40). <br />However, for preliminary design and cost estimating purposes, a slope stability analysis is not <br />