The application allows for the verification of the anchor’s pull-out resistance from the soil. The ultimate bond strength (pull-out resistance) depends on multiple factors, including the type of foundation soil, the injection method, drilling characteristics, etc.
In very compact soils and rocks, the shear stress at the cylindrical grout-soil interface decays exponentially along the foundation shaft, according to the following law:
τx/τ0=exp(-Ax/d)=R (Hawkes & Evans 1951)
Stress Calculation Scheme
where:
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τ0 = shear stress at the top (beginning) of the foundation shaft;
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τx = shear stress at the coordinate x along the foundation shaft;
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A = Ea / Er = parameter defining the ratio between the shear stress in the foundation soil and the axial stress in the anchor bar;
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Ea = elastic modulus of the anchor shaft filling material (grout);
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Er = elastic modulus of the bar or tendon;
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R = shear stress ratio.
The concentration of shear stresses at the top (beginning) of the anchor shaft is potentially capable of causing the progressive failure of an anchor foundation.