Pile Group Analysis Program

The program, PIGLET, allows analysis of the response of pile groups, under working load conditions, to provide stiffness and flexibility matrices for the pile cap (including torsional modes) under axial, lateral and moment loading at the head of each pile, and profiles of bending moment and lateral deflection down selected piles. Piles are permitted to rake in any direction. The program can analyse piles of different length, as well as of different diameter. Although the analysis is essentially elastic, the effects of non-linear axial and lateral response of individual piles may be quantified, including axial failure of piles that reach specified limiting loads.


The program runs from an ExcelTM workbook, which calls a Fortran DLL. All input data and output from the program is within different worksheets in the Excel workbook.

The main program features are summarised below:

  • Fast closed-form elastic solutions with full pile-soil-pile interaction; groups of up to 1000 piles, with up to 100 load cases for any given analysis

  • Independent soil modulus values for axial and lateral loading

  • Vertical loading only: rigid or flexible pile cap; general loading: rigid pile cap

  • Rotational ‘fixity’ of piles to pile cap variable from pinned to fully fixed

  • Three-dimensional raking and loading of piles (including torsion); independent pile bending rigidity in x:z and y:z planes (e.g. for H-piles or barrettes).

  • Full stiffness and flexibility matrices provided for (rigid) pile cap

  • Axial and lateral load and bending moments at head of each pile

  • Profiles of bending moment, shear and lateral deflection for specified piles

  • Non-linear axial pile response: limiting axial capacity specified for each pile

  • Non-linear lateral analysis, specifying rate of reduction in secant stiffness with lateral deflection.


The program can be supplied by contacting Mark Randolph, including a PDF manual, and will run on any desk-top or notebook computer where Excel is available.