Numerical investigation of negative skin friction in battered piles group Based on pile position: a consolidation study

Batter piles, known for their lateral force resistance, often experience significant bending-induced settlements. When a pile's settlement is less than that of the surrounding soil, negative skin friction (NSF) emerges. This article inspects the NSF behaviour of batter pile groups during consolidation. First, a novel mathematical model (MM) combining the inclined load-transfer method and the two-dimensional consolidation theory is presented. To justify the MM's consistency, a 3D finite element model (FEM) was created. Once the proposed dual approach was validated against the referenced cases, parametric studies examined the time and the load consolidation effects across three pile configurations. The outcomes illustrate that the vertical and the 15 degrees' batter piles exhibit similar NSF performance under a surcharge load (SL), while 30 degrees' batter piles generate a higher NSF initially and later develop complete positive skin friction. The SL significantly impacts the neutral plane (NP) in small-load situations, with the 15 degrees' piles having a shallower NP than the vertical piles, and the 30 degrees' piles' NP permanently located at the pile end. Over time, the NP depth decreases, with the vertical piles having the deepest NP followed by the 15 degrees' and 30 degrees' piles. The pile position's influence on the NSF distribution is more pronounced in the batter piles, with the inner piles showing a more superficial NP.