The individual pile position and length for each pile within the pile group can be entered in PileGroup program through the dialog as shown in the following figure. The above dialog enables the users to specify various pile length and layout parameters for the pile group analysis in a simple and efficient way. The parameters include pile length, pile section type, pile position (X and Z Coordinates), pile batters in XY and ZY planes. Pile top level also can be input in the dialog however it is only used for geometry and results display. The users can specify the following inputs related to the pile position, pile type and pile length for the pile group analysis: Number of the piles within the pile group. The minimum number is 2 and the maximum number is 50 in the current version. The user can add or delete the pile by clicking “Add” and “Delete” buttons just below the pile number list box; X and Z position of each pile on the pile cap plane (XZ Plane); Pile length for each individual pile; Pile section type for each individual pile. Note that PileGroup allows the users to adopt different pile section types within the same pile group; Pile batter in XY plane, Xb – the maximum batter is 1; Pile batter in ZY plane, Zb – the maximum batter is 1; and Pile top level. Note that this property will not affect the analysis results and is just used for displaying purpose. The coordinate system used by the program can be viewed by the users through clocking “show coordinate system” button just below the pile position and length input area. The following figure shows the coordinate system used in the program for pile groups. The global X and Z directions are on the horizontal pile cap plane and the global Y direction is vertical to the pile cap plane. Three-dimensional view of the pile group will be automatically updated during the input of the pile layout, length and batter degree input parameters. The users can freely rotate and zoom 3D displaying of the pile group through the mouse. The following figure shows the three-dimensional view of the pile group.

Various pile top boundary conditions are available in PileLAT and the users can access those options from the dialog at the left side of the main program interface as shown in the figure below. The following five different options can be adopted by the user for the pile top boundary condition as shown in the figure above: · Option 1: Free Pile Head. Pile head is free to move laterally and rotate. Usually, pin or hinge connections are assumed between pile cap and piles; · Option 2: Rigid Pile Head. Pile head can move laterally but cannot rotate. Moment will be generated at the pile head; · Option 3: Partially Restrained Pile Head. Rotational spring value needs to be provided in the unit of moment per unit slope; · Option 4: Specified Deflection and Applied Bending Moment; and · Option 5: Specified Deflection and Specified Rotation.

Both driven and bored piles are supported by PileLAT program and the following cross section types can be used in the analysis of single piles under lateral loading: Driven Piles: · Circular Section; · Rectangular Section; · Octagonal Section; · H Section; · Pipe Section; and · User-defined Section Bored Piles or Drilled Shaft: · Circular Section; · Rectangular Section; and · User-defined Section

Various p-y curves are implemented in PileLAT to analyze the pile behvaiour under the lateral loading. Typical p-y curve plots are shown in the figure below.

Nonlinear t-z curves for driven piles into sand can be based on the recommendation from Mosher (1984) where a hyperbolic representation of t-z curve was proposed. The initial slope Kf of the curve is given in the following table as a function of internal friction angle. This nonlinear t-z curve as recommended by Mosher (1984) has been adopted by PileAXL program for driven pile into cohesionless materials. Refer to the figure below for a typical t-z curve based on Mosher (1984)'s approach.

Nonlinear t-z load transfer curves adopted in PileAXL program have been summarized and shown in the table below.