RSPile Overview

LATERAL PILE ANALYSIS

In order to properly analyze a laterally loaded pile foundation in soil/rock, a nonlinear relationship needs to be applied that provides soil resistance as a function of pile deflection.

For this type of analysis, the main parameter to take from the soil is a reaction modulus. It is defined as the resistance from the soil at a point along the depth of the pile divided by the horizontal deflection of the pile at that point. RSPile defines this reaction modulus (Epy) using the secant of the p-y curve.

p-y curves are developed at specific depths, indicating the soil reaction modulus is both a function of pile deflection (y) and the depth below the ground surface (z).

AXIAL PILE ANALYSIS

The stress-strain relationship for an axially loaded pile can be described through three loading mechanisms: axial deformation in the pile, soil skin friction along the shaft, and soil end-bearing. Using a spring-mass model in which springs represent material stiffness, numerical techniques can be employed to conduct the load-settlement analysis.

As per the assumed sign convention, the x-axis typically corresponds to the distance along the pile, while the z-axis corresponds to the distance below the ground surface. However, since the pile length above the ground surface does not affect the stress distribution of the pile below ground, the z-axis has been traditionally used to denote the distance along the embedded pile length.

The t-z curve method using finite element analysis was employed to solve the governing differential equation. The t-z curve method allows for simulation of the non-linear stress-strain behavior in soil by employing non-linear stiffness curves denoted as t-z curves for soil shear elements and Q-z curve for the soil end bearing element. The stiffness is computed at each iteration based on the solved displacement values.

DRIVEN PILE ANALYSIS

The Driven Pile Analysis option in RSPile was developed based on DRIVEN, from the FHWA.

Three capacities are calculated by the program:

• Restrike - Static skin and end bearing resistance for the entire soil profile. The effect of soft soils or scour conditions are not considered.
• Driving - Users can enter a loss of soil strength in the soil profile for each soil layer due to the effects of driving. The driving computations are based upon the restrike calculations minus the soil strength loss due to driving.
• Ultimate - The ultimate capacity available to resist applied loads. Ultimate capacity computations consider the effects of soft soil conditions or scour.

BORED PILE ANALYSIS

The Bored Pile Analysis option in RSPile was developed based on FHWA and AASHTO standards.

The Ultimate capacity in resisting applied loads can be computed. Ultimate capacity computations can consider the effects of soft soil conditions or scour.

HELICAL PILE ANALYSIS

The Helical Pile Analysis option calculates the ultimate capacities of helical piles in compression and uplift.

The ultimate capacity is determined by Limit State Analysis and can be governed by either cylindrical shear between the helices or individual end bearing on the helix plates. The user has the flexibility to include or neglect adhesion on the shaft.

GROUP PILE ANALYSIS

The lateral analysis of a group of piles, connected by a cap, can be done in the Group Pile Analysis mode.

Within a group, piles can be different types or sizes, be installed on different batter angles, and consist of different materials. The default assumption is that the piles are far enough from the piles that there is no significant pile-soil-pile interaction. Pile-soil-pile interaction can be accounted for, however, by specifying multipliers for the soil resistance curves.

The Cap Designer is used to define the pile locations, loading and connectivity.