Lateral Earth Pressure on Non-Yielding Walls Supporting Over-Consolidated Sand

Abstract

The most important problem associated with retaining wall structures is the additional compaction-induced lateral earth pressure. Currently, none of the available design methods used to calculate the lateral earth force on non-yielding walls can explicitly consider the compaction-induced lateral force. Therefore, there is a need to quantify the compaction-induced lateral earth force and modify the current design methods to consider this additional force. To achieve this objective, a numerical model was developed using the program FLAC and was validated against carefully conducted experimental tests. Material properties such as backfill soil friction angle, wall panel elastic modulus, and sand degree of consolidation (compaction), were varied between the numerical models to isolate their effects on the wall responses. Effects of these properties on the lateral earth pressure magnitudes and distributions, wall lateral deflection, horizontal vertical earth force, and the location of the resultant earth force were investigated. Results indicated that increasing the friction angle of the backfill soil, elasticity of the wall, and inclination of model wall facing the panel resulted in a decrease in the lateral deflection of the wall panel. The location of the resultant lateral force increased when the friction angle of backfill soil increased. On the other hand, increasing the degree of consolidation of the backfill soil as well as the elasticity of facing panel lowered the location of the resultant force acting on the wall. For dynamic responses, the maximum dynamic and residual lateral deflection increments increased with the backfill soil friction angle and decreased with both the sand backfill consolidation ratio and the wall panel elastic modulus. Both dynamic and residual earth pressure distribution were different from the static distribution, regardless of the material properties. The location of the resultant force was slightly affected by the backfill soil degree of consolidation and wall panel elasticity. A comparison between theoretical and numerical results indicated that the distribution of earth pressure resulting from over-consolidated sand on non-yielding walls is not hydrostatic nor does it follow the traditional Jaky's formula.