Modeling of laterally loaded drilled shaft within an MSE wall under cyclic loading

Currently there is no design guideline to consider the interaction between Mechanically Stabilized Earth (MSE) wall and the drilled shafts constructed inside the MSE wall under cyclic loading. The behaviors of the MSE wall and the drilled shafts under cyclic loading are important because the deformation of MSE wall and capacity of the drilled shaft under cyclic loading may be significantly different from these under static loading. This study encompasses a numerical study which investigates the influence of various factors on interaction between the MSE wall and the drilled shaft that is subjected to cyclic loading.

The three-dimensional (3D) finite difference software, FLAC3D, is utilized in this study for the numerical analysis. A numerical model of a MSE wall is developed and calibrated using full-scale field test data. Thereafter a parametric study has been performed to investigate the influence of different factors on the interaction between the MSE wall and the drilled shaft that is subjected to cyclic loading. The investigated factors include backfill friction angle, backfill soil modulus, geogrid stiffness, cyclic loading magnitude, shaft length, and location of drilled shaft. The impact of those factors on lateral deflection in drilled shaft, horizontal and vertical deflections of MSE wall, lateral earth pressure, and stress and strain in geogrid is evaluated due to cyclic loading on the drilled shaft.

The overall drilled shaft and MSE wall lateral deflection increases at all the parametric studies under cyclic loading. From the details parametric study results it can be concluded that the increase of tension and strain in geogrid varies at different elevations. The maximum geogrid tension and strain is found at 5.9 m elevation. The increase of lateral earth pressure also changes with the change of elevation. The maximum lateral earth pressure increase is found at 5.1 m elevation for all parametric study.