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- 103 -SURFACE ON WHICH PRESSUREIS CALCULATEDDEPTHTENSIONOFZONETRIAL WEDGES FORACTIVE PRESSUREFORCEPOLYGON FOR TYPICAL WEDGECOMBINATIONOFNOTESFORCE POLYGONS TO OBTAIN1 The above example shows Rankine's conditions but the same principle applies forCoulomb's conditions. (Adhesion on the back of the wall is ignored).2. For direction P A see Figure 10 (Rankine's conditions) or Figure 6 (Coulomb'scondi tions).MAX.3. See Figures 11 and 12 for point of application.4. See Figure 12 for resultant pressure diagram.5. The trial wedge method may be used for a level or constantly sloping groundsurface.TRIAL WEDGE METHOD-COHESIVE SOIL FIGURE 7PA