Experimental Study of the Earth Pressure Evolution on a Model Wall Rotating about Its Base

Abstract

Quantifying the earth pressure acting on retaining structures is essential for a number of engineering applications, including the assessment of damaged structures. In response to the widespread corrosion found in many cantilever retaining walls in Switzerland, this study investigates the evolution of the earth pressure acting on a retaining wall rotating about its base: the dominant deformation mode for such structures. In a controlled setup, a scaled cantilever retaining wall is first backfilled and then subjected to rotation about its base. An extensive experimental program was conducted to evaluate the effects of different soil properties, packing densities, and initial soil stresses on the earth pressure during the life of a wall. Accurate measurements allow the stick-slip behavior typical of granular soils to be observed. An analysis of this behavior suggests that its impact on the practical safety assessment of retaining walls is negligible. Tests performed under 3D conditions show how local damage to a section of the wall results in a lower active earth pressure value on that section due to stress redistribution, which causes an increase in pressure on adjacent sections. It is also observed how the initial earth pressure acting on retaining walls after backfilling results from a perturbed stress state due to wall deflection and wall friction. Its distribution is bilinear for uncompacted soil and nonlinear for compacted soil. Loosely packed soil exerts higher pressures than densely packed soil. The unloading process shows the expected behavior of loose and dense soil: it is slower and monotonic in loose soil and faster in dense soil, where the initial unloading is followed by reloading due to softening in the backfill. The experimental results are available in a public repository and can serve as a resource for the development and validation of improved verification procedures.