Experimental Setup for Measuring p-y Curves of Rigid Walls Supporting Granular Backfill

In the context of performance-based design, there is interest in quantifying the relationship between the lateral earth pressure and the wall displacement using the concept of p-y curves. Although p-y curves have been extensively used in the analysis of piles, their use in the analysis of rigid walls is still in its early stages. There is a need for realistic and simplified models that could describe the p-y relationship for rigid walls to be used as input in robust soil-structure-interaction analyses. This paper aims at studying the development of lateral stresses behind rigid walls in the context of p-y curves using a laboratory-scale retaining wall prototype that is 0.5 m wide, 1.2 m high, and 2.6 m long. The main objective is to provide insight on the p-y response behind rigid walls under static and cyclic loading conditions for different backfill densities and confinement conditions. Results indicate that the proposed experimental setup yields repeatable and consistent measurements of the p-y response, which was found to be highly nonlinear and not adequately represented by the simple elastic-perfectly plastic model that was adopted in the literature in modeling soil-structure interaction between basement walls and sand backfill. Unique results from the cyclic tests indicated a process of densification that dominated the volumetric tendency of the sand during cyclic loading, with the p-y curves showing a significant increase in stiffness and maximum pressure at the passive side after 10 loading cycles. The gradual increase in stiffness decreased with the number of cycles until convergence in the passive stiffness was observed after 9 to 10 cycles.