Analysis of Sheet Pile Wall
A pile sheeting wall is analyzed using a standard approach that account for the effect of earth pressures. In general, the active earth pressure develops behind the structure while the passive earth pressure appears in front of the structure.
Based on the theory of limit states the program searches in an iterative way a point on the wall to satisfy the moment equation of equilibrium in the form:
Once this is accomplished, the program continues by determining the wall heel location for which the equilibrium of shear forces is fulfilled (computation of depth of fixed end). The overall length of the analyzed structure is found this way.
When applying approach based on the factor of safety the program searches, in an iterative way, a point to get:
It is obvious that the distribution of internal forces resulting from this approach is not very realistic. In some countries, however, this approach is required.
The computation can be driven either by choosing a minimal dimensioning pressure or by reduction of passive pressure. Assuming the actual magnitude of the passive earth pressure provides deformations of the analyzed structure, which cannot usually occur. The actual passive pressure can attain for walls free of deformation the value of pressure at rest as well as all intermediate values up to the value of passive pressure for fully deformed wall (rotation app. 10 mRad - i.e. deformation 10 mm per 1 m of structure height). Therefore it is reasonable to consider reduced values of the passive earth pressure by setting the value of the "Coefficient of reduction of passive pressure" to less than or equal to one. The following values are recommended:
- 0.67 reduces deformations app. by one half
- 0.50 approximately corresponds to deformation of structure loaded by increased active earth pressure
- 0.33 approximately corresponds to deformation of structure loaded by the pressure at rest, structure reaches app. 20 percent of its original deformations