The theoretical concepts used in the PYWALL software extend beyond the conventional method of analysis and design of flexible retaining walls based on limit-equilibrium theory. As a difference to conventional pratice, the PYWALL method includes the effects of soil-structure interaction.

Modern methods of analyses of the behavior of reatining structures consider realistic soil conditions and relevant details of the structural system. Therefore, a rational method of analysis and design must include the nonlinear soil-resistance-displacement relationships, pile spacings, penetration depths and structural properties. PYWALL considers soil-structure interaction by using a beam-column model and can analyze the behavior of a flexible retaining wall or soldier-pile wall with or without tiebacks or bracing systems.


  • Simplified evaluations of the impacts of staged construction (for up to 5 stages).
  • Quick and combined observation of results of wall deflections and bending moments in different construction stages.
  • Evaluate short and long-term wall response for user-defined soil properties and loading conditions.
  • P—y curves for weak rock, soft clay, stiff clay with and without free water, sand, silt (c-phi soil), and strong rock (Vuggy Limestone).
  • View combined output of lateral movements, shear and bending moment along the length of the wall and in a single page for quick observation of results and to help users in the verification process.
  • A sloping backfill can be specified and when selected, the program takes into account this slope angle when generating earth pressures of triangular distribution acting against the wall.
  • Automatically generate active earth pressures with triangular distributions based on the traditional Rankine theory. When selected, users may also specify a constant load factor to increase or decrease the magnitude of earth pressures generated by the program.
  • In addition to earth pressures, concentrated loads may be specified at any point(s) in the wall. The concentrated loads can be a specified lateral load, bending moment or axial load.
  • Additional surcharge loads may be specified in the back side of the wall. Four types of surcharge loads can be specified: area load, point load, line load and/or strip load.
  • Struts or braces may be specified at any height(s) of the wall. The stiffness of these elements can be modeled as linear elastic springs or fully nonlinear springs.
  • Optionally, users may calculate externally and input any type of earth-pressure distributions. The program can interpolate linearly between inputted values of pressure placed at different depths.
  • Specify deflections or slopes at any point in the height of the wall. This input option allows designers to make a better simulation of braces having limited movements or to model specific conections between braces and wall.
  • Flexural stiffness of the wall may be varied and/or linearly interpolated at different wall heights.
  • Soil-resistance (p—y) curves can be internally generated by the program for the following 7 types of soils: soft clay, stiff clay with or without free water, sand, silt (c-phi soil), weak rock and rock. Internally-generated p-y curves may be printed for reviews or reference.
  • Users may optionally input their own soil-resistance (p—y) curves at any desired depth. PYWALL uses double-precision algorithms to reach better solutions in the nonlinear iterations.
  • User-defined multipliers can be specified to increase or reduce the soil resistance (p—y curves) at any depth of the wall below the dredge line. For instance, this feature may be used in seismic conditions to reduce the response of liquefied layers, or to consider creep effects for long-term conditions or for closely-spaced piles.