New consolidation equation for soil-cement pile improved ground

During the consolidation process of a soil-cement pile unit cell, the excess pore pressure of the pile cannot be assumed to be zero at any given time. However, the higher coefficient of consolidation and coefficient of permeability of the soil-cement pile relative to that of the surrounding clay allows its excess pore-water pressure to dissipate quickly. This subsequently creates a hydraulic gradient with the adjacent surrounding clay and allows the pore water from the latter to flow radially. While the consolidation process of the soil-cement pile controls the radial drainage of the pore water into the surrounding clay, the entrance of the pore water from the surrounding clay also subsequently alters the consolidation process of the pile. A new governing equation that describes the interdependent consolidation of the pile and its surrounding clay in a typical unit cell of soil-cement pile improved ground has been derived. Solutions to this governing equation corresponding to two extreme compatibility conditions of load transfer device, namely, equal stress and equal strain conditions, are presented. Moreover, the procedure to estimate the consolidation of this improved ground when it is loaded through a partially rigid load transfer device is also discussed. Finally, design charts are generated and one case history is analyzed to verify the use of this new governing consolidation equation.