Abstract: The composite foundation with permeable and impermeable piles can promote the consolidation process of soft soil, and enhance the strength of foundation, implying practical applications for the soft ground treatment. Based on the axisymmetric consolidation model, a differential equation governing the consolidation of combined composite foundation subjected to an instant loading is established, considering the volume compression of the permeable pile. The analytical solution is derived for given initial and boundary conditions. Then, the solution is verified through the comparison with the existing solution. The main influencing factors such as disturbance effect, well resistance effect and compression modulus are analyzed to explore the consolidation behavior of composite foundation. The results show that the consolidation rate of the combined composite foundation will be overrated without considering the volume change of the permeable columns. The consolidation rate can be accelerated by reducing the effects of well resistance and the disturbance effect of permeable column or increasing the replacement ratio and the compression modulus, reducing the post-construction settlement in practical applications.

Key words: combined composite foundation, volume change, consolidation, analytical analysis, soft soil