Based on three-dimensional numerical simulations of composite foundation both on the condition of ordinary use and ground subsidence

changes of settlement

skin friction distribution and axial force of pile in composite foundation after ground subsidence induced by groundwater level lowering are analyzed. It is shown that

settlement of reinforced pile and foundation increases

and neutral point in pile moves down gradually

axial forces in reinforced pile increase gradually along with ground subsidence increasing. In reinforced piles of composite foundation

neutral point in centre pile is the lowest

neutral point in border pile is the second

neutral point in corner pile is the highest. Along with ground subsidence increasing

the differences of neutral point position in centre pile

border pile and corner pile decrease gradually

the length impacted by negative skin friction of upper part pile over neutral point lengthens gradually

value of negative skin friction increases gradually.