DHARM328 GEOTECHNICAL ENGINEERING
For example, the values for all slices may be tabulated as follows and summed up:Slice no. Area m^2 Weight W (kN) Normal component N (kN) Tangential components T (kN)1.
2.
3.
.
.. Sum, ΣN = ... kN ΣT = ... kN
Another approach is to draw the N-curve and T-curve, showing the variation of N- and
T-values for the various slices with the breadth of the slice as the base, as shown in Fig. 9.11.
q 2 3 4 5 6 7 8 9(^121110)
W 1
T 1
N 1
b
T (^12) T
11
(a) Resolution of weights of slices into normal
and tangential components
(–ve)(–ve)
(b) N-curve
(c) T-curve
b : Constant breadth of slices
Fig. 9.11 Determination of ΣN and ΣT in the Swedish method of slices
If the areas under the N- and T-curves are found out by a planimeter or otherwise and
divided by the constant breadth of the slices, relatively accurate values of ΣN and ΣT will be
obtained. The weights of the respective slices can be considered to be approximately propor-
tional to the mid-ordinates and the scale can be easily determined.
The Swedish method of slices is a general approach which is equally applicable to homo-
geneous soils, stratified deposits, partially submerged cases and non-uniform slopes. Seepage
effects also can be considered.
Location of the Most Critical Circle
The centre of the most critical circle can be found only by trial and error. A number of
slip circles are to be analysed and the minimum factor of safety finally obtained. One of the
procedures suggested for this is shown in Fig. 9.12.