The effect of cohesion on passive pressure

6.13.1 The Rankine theory

Rankine's theory has been developed by Bell (1915) for the case of a frictional/ cohesive soil. His solution for a soil with a horizontal surface is:

6.13.2 The Coulomb theory

As has been discussed, a clay has a non-linear stress-strain relationship and its shear strength depends upon its previous stress history. Add to this the complications of non-uniform strain patterns within a passive resistance zone and it is obvious that any design approach must be an empirical approach based on experimental work.

A similar equation to that of Bell can be used for passive pressure values when the effect of wall friction and adhesion are taken into account.

The passive pressure acting normally to the wall at a depth h can be defined as:

PPh = Kp7h + cKpc where c = operating value of cohesion.

Various values of Kp and K^. are given in Table 6.3 for the straightforward case of ¡3 = 0, xj) = 90°. As with the active pressure coefficients given in Table 6.1, they give the value of the pressure acting normally to the wall.

Table 6.3 Values of Kp and Kpc for a cohesive soil.
0 0

Responses

  • norma
    How to account for cohesion in passive pressure?
    2 years ago
  • milena
    What is the effect of cohesion on active pressure?
    2 years ago

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