Cress Help - Soil mechanics - B24

Active, passive and neutral soil pressure 

The calculation rule generates values for Kactive and Kpassive according to the method of Rankine. This method assumes a vertical revetment, behind which is a horizontal platform or a slope. Values for Ka can be read from the following table :
b j = 26 j = 28 j = 30 j = 32 j = 34 j = 36 j = 38 j = 40 j = 42
0 0.3905 0.3610 0.3333 0.3073 0.2827 0.2596 0.2379 0.2174 0.1982
5 0.3959 0.3656 0.3372 0.3105 0.2855 0.2620 0.2399 0.2192 0.1997
10 0.4134 0.3802 0.3495 0.3210 0.2944 0.2696 0.2464 0.2247 0.2044
15 0.4480 0.4086 0.3729 0.3405 0.3108 0.2834 0.2581 0.2346 0.2129
20 0.5152 0.4605 0.4142 0.3739 0.3381 0.3060 0.2769 0.2504 0.2262
25 0.6999 0.5727 0.4936 0.4336 0.3847 0.3431 0.3070 0.2750 0.2465
30 - - 0.8660 0.5741 0.4776 0.4105 0.3582 0.3151 0.2784
35 - - - - - 0.5971 0.4677 0.3906 0.3340
40 - - - - - - - 0.7660 0.4668

Values for Kp can be read from the following table :
b j = 26 j = 28 j = 30 j = 32 j = 34 j = 36 j = 38 j = 40 j = 42
0                  
5                  
10                  
15                  
20                  
25                  
30                  
35                  
40                  


The above values are given by the following equations :

   equation 1

   equation 2

in which :

Kneutral:
In practice values of K0 between 0.5 and 1 are often used. In these cases values close to 1are used for weak clay, while for sand lower values are usually taken (for example 0.6 or 0.7).

Reference:
[a] Foundation Analysis and Design, Joseph E. Bowles, 5th edition.
[b] Grondmechanica, A. Verruijt, Delft 1990.