Theoretical Study on the Consolidation of Composite Foundation with Multiple Types of Reinforcements Accounting for Consolidation Deformation of Stone Columns

The technology of composite foundation reinforcement is developing from a composite foundation reinforced by a single column type to one by multiple columns. Aiming at the consolidation problem of the combined composite foundation. This paper establishes a consolidation calculation model with bidirectional flowing for a composite foundation strengthened by stone columns and impervious piles that can describe different distribution forms of piles. The volume compression of central stone column and peripheral ones are considered by assuming that the difference between the water flowing into the central stone column and peripheral ones in the radial direction and the water flowing out from each in the vertical direction. The analytical solutions of the combined composite foundation consolidation under four various loading methods are deduced by considering the well resistance effect and smear effect of stone columns, as well as the disturbance effect of impervious piles and the consolidation behavior of the composite foundation is investigated. The results showed that a greater permeability coefficient of the stone columns, a denser distribution of the stone columns and the impervious piles, and a higher compression modulus of the impervious piles accelerates the consolidation of the composite foundation. The smearing impact of stone columns on the consolidation of the composite foundation exceeds that of impervious piles. If the volume compression of stone columns is ignored, the consolidation rate of the composite foundation will overestimate, and the error increases with the decrease in radius ratio. There is a good agreement between the predicted settlement by the analytical solution and the measured settlement.