The effect of wall stiffness on the behaviour of a propped retaining wall

In this note numerical analysis has been used to investigate the effect of wall flexibility on the behaviour of a propped embedded retaining wall. It has been shown that for flexible walls of the sheet pile type the predicted bending moments are much lower than that given by the simple limit equilibrium type of design calculation. As the stiffness of the wall increases then so do the bending moments. For walls installed in low k0 (=0.5) soils the bending moments approach the limit equilibrium values as the wall stiffness increases. These results are in full agreement with the model tests of Rowe (1952). However, for stiff walls in high k0 (>1) soils the bending moments greatly exceed the limit equilibrium values. A similar trend is observed for the prop forces. The results imply that for a diaphragm or secant pile wall in stiff clay with a high k0 the bending moments and prop forces could exceed design values based on the limit equilibrium type of design calculations. Curves showing the variation in the ratios of: (a) maximum bending moment to that predicted by limit equilibrium; (b) the prop force to that predicted by limit equilibrium, with wall stiffness for various in situ k0 values are given. These may be useful for preliminary design. (TRRL)