Mobilisable strength design for flexible embedded retaining walls

Soil–structure interaction may have an important influence on the behaviour of embedded retaining walls, affecting both wall bending moments and ground movements. However, it can be difficult and time consuming to capture in design, especially in a way that gives a physical insight into the key behavioural mechanisms involved. A calculation procedure has been developed for retaining walls propped near the crest that takes into account both the non-linearity of the stress–strain behaviour of the soil and the flexibility of the wall. Results for different pore water pressure conditions, soil strengths and soil and wall stiffnesses are presented in the form of look-up charts, and are compared with those derived from factored limit equilibrium analyses. A dimensionless parameter is introduced to represent the relative soil–wall stiffness, and its importance is demonstrated. A critical flexibility ratio is identified at which the bending moments start to reduce below those given by a conventional limit equilibrium calculation. This ratio is linked to the wall deflection, and is used to distinguish a stiff from a flexible system in soils of different strengths and pore water pressure conditions. The approach is discussed in relation to previous studies.