In order to execute the check on the limit load of the generic micropile it is necessary to determine the rate of vertical rate and moment which is going to be absorbed by the generic micropile. In order to do this, you must refer to the following calculation diagram:
Reference diagram for the distribution of stresses
Where N and M are the actions unloaded by the superstructure (in this case, the weir body). The previous diagram is used to distribute the stresses upon the micropiles. The distribution of stresses is achieved assuming that the foundation connected to the micropiles is infinitely rigid, so that the distribution itself can be considered as having a linear course:
Linear course of the piles reaction
In order to evaluate the stress loaded onto a single micropile it is necessary to previously determine the eccentricity of the normal stress N with respect to the barycentre of the piling (identified by the coordinate xgp). Said eccentricity is evaluated through the following formula:
The additional term (xgf-xgp) allows taking into consideration the event that the geometrical barycentre of the piling and the geometrical barycentre of the foundation are not coincident. At this point it is possible to apply the following formula:
Where np is the number of piles, xi is the la coordinate x of the ith pile with regard to the global reference origin, pi is the vertical unloading upon the ith pile, Jx is the moment of inertia of the piling with respect to its barycentre, evaluated though the following formula:
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