Limit Equilibrium Analysis Methods

Limit Equilibrium Analysis Methods - Information and Advantages

This section examines the limit equilibrium methods for shoring design and analysis, as well as, the advantages of the use of Limit Equilibrium Analysis (LEM) Method.

Limit equilibrium is an analysis methods where limit state conditions are assumed. For excavations and earth retaining structures this usually means that earth pressures are assumed on both the retained and excavated sides. These pressures may represent a failure state such as active or passive lateral earth pressures, or an assumed redistribution such as diagrams by Peck or FHWA.

In Limit Equilibrium Analysis, the retaining wall is analyzed to provide moment and force equilibrium, when possible. Support reactions are also calculated, typically by using the tributary area method.

Limit Equilibrium Analysis - Cantilever sheet pile wall design with DeepEX

The advantages of limit equilibrium methods include:

a) They form a well known analysis method

b) They can provide quick answers

c) The assumed limit conditions are well understood

The disadvantages of limit-equilibrium methods include:

a) The analysis is valid only for simple conditions

b) Soil structure interaction is not properly captured

c) Calculated wall displacements are unrealistic for excavations with multiple bracing levels.

d) Computed wall bending moments are possibly uncoservative when more than one support levels are used.

e) Construction stage history is totally ignored.

Concluding, it always adds value to perform a limit-equilibrium analysis that can provide a backbone against which to compare a more rigorous non-linear elastoplastic solution.

DeepEX includes the capabiliy to perform both non-linear and limit-equilibrium analysis methods. Please select any of the options below to explore some typical examples.