Analytical modeling on consolidation of stiffened deep mixed column‐reinforced soft soil under embankment

Abstract

SummaryStiffened deep mixed (SDM) column is a new ground improvement technique to improve soft soil, which can be used to increase bearing capacity, reduce deformation, and enhance stability of soft soil. This technique has been successfully adopted to support the highway and railway embankments over soft soils in China and other countries. However, there have been limited investigations on its consolidation under embankment loading. This paper developed an analytical solution for the consolidation of embankment over soft soil with SDM column in which core pile is equal to or shorter than outer DM column. The consolidation problem was simplified as a consolidation of composite soil considering the load shear effect of core pile. The developed solution was verified by a comparison with the results computed by three‐dimensional (3‐D) finite element analysis. A parametric study based on the derived solution was conducted to investigate influence factors—length of core pile, diameter of core pile, diameter of SDM column, modulus of DM column, and permeability coefficient of DM column—on the consolidation behavior of SDM column‐supported embankment over soft soil. The developed solution was applied to a case history of SDM column‐supported embankment, and a good agreement was found between the predictions and the field measurements.

Consolidation calculation of a foundation partially penetrated by concrete‐cored gravel (CCG) columns

“…They concluded that the stone columns mainly affect the anterior drainage process of the composite foundation. Zhang et al 13 . and Ye et al 14 .…”

“…7 They concluded that the stone columns mainly affect the anterior drainage process of the composite foundation. Zhang et al 13 and Ye et al 14 presented analytical solutions for the consolidation of a doublelayered foundation improved by deep mixed columns. Zhang et al 15 developed the consolidation solutions of the foundation partially penetrated with short deep mixed columns and long prefabricated vertical drains based on the circular drainage wall model.…”

“…According to Terzaghi's theory, if only vertical drainage occurs in the unpenetrated layer, its differential consolidation equation can be represented as Equation (13).…”

Analytical Solution for Consolidation Behaviors of Combined Composite Foundation Reinforced with Penetrated PCCSs and Floating DM Columns

“…Similarly, the combination concept of two types of piles also applies to the single pile to form the composite pile, which can exploit both merits. The precast concrete pile reinforced with cement-treated soil (PCCS) is a novel type of composite pile, which is created by driving the PC pile, termed inner core, into the DM column, termed outer core [18][19][20][21]. In order to increase the pile spacing and give full play to the economic merits of the PCCS, a novel CCF reinforced by penetrated PCCSs and floating DM columns is proposed and utilized to improve soft soils.…”

“…The bearing performances of the PCCS were investigated by means of experimental, theoretical, and numerical analysis under vertical and lateral loads [26][27][28][29][30][31]. The inner core is installed to bear external loads, while the outer core can increase the shaft friction of the inner core and effectively transfer the inner core's axial force to the surrounding soil [18]. The PCCS can reduce costs by nearly 30% under the same bearing capacity provided by the PCCS and the piles with the same geometric dimensioning [32].…”