Question

I have a message "Pile Nearing Punch Through" in my collapse analysis. What does this mean? 

Answers

• The following plot shows a typical pile axis load vs. axial deflection response when the pile-soil interaction is modeled using Winkler soil springs. The pile capacity, as marked in the plot, is associated with the peak of the curve.
  
  
• During a collapse analysis, when the pile reaches its capacity and passes it (punch-through), we usually observe an immediate drop in the soil resistance and a relatively large deformation. Still, the soil resistance does not necessarily become zero, and we may have some residual axial resistance in the pile. Note that the axial force resistance is always smaller than the pile capacity, and the pile experiences large deformation. 
  
  
• While the pile capacity is only a function of the pile axial displacement, the pile plasticity depends on the axial load, lateral load, and bending moment applied at the pile head. For example, a pile with an axial load at a fraction of its capacity may become plastic due to a large lateral force or a bending moment at its pile head.
  
  
• So, a pile may experience a punch-through because of reaches its compression capacity first. As the analysis progresses, because of large deformation, additional lateral force or bending moment may be applied at the pile, leading to the pile's plasticity.