Modelling of laterally loaded drilled shaft group in mechanically stabilised earth wall

This paper proposes a numerical model, calibrated by a full-scale field test, to investigate the behaviour of a laterally loaded shaft group built within a mechanically stabilised earth wall. The numerical modelling yielded results of the geogrid strain and the lateral earth pressure distributions. It was found that the strain was a maximum at the edge of the each shaft, and decreased rapidly with distance from the shaft. The additional lateral earth pressure induced by the shaft group is non-linear and non-monotonic. The calibrated numerical model was then used to investigate the impacts of various factors on the group effect. It was found that the required minimum spacing to avoid group effect increased with decreasing modulus of the backfill material. The friction angle of the backfill material and the geogrid tensile stiffness did not have a significant influence on the group effect. Based on this study, a formula to estimate the minimum spacing to avoid group effect was developed.