Elliptical cylindrical equivalent model for consolidation of unsaturated soil improved by PVD

Self Cite

A governing equation for large‐strain consolidation of PVD‐improved soil is developed based on the equivalent elliptical cylindrical model, which accounts for depth‐dependent initial void ratio and initial effective stress induced by soil self‐weight, well resistance with variable discharge capacity, time‐dependent load, and nonlinear variations of compressibility and permeability. Then, a numerical solution is obtained by means of COMSOL Multiphysics and is validated through comparisons with existing solutions and measured data. The parametric studies show that the difference between large‐strain consolidation and small‐strain consolidation reduces with the decreases of the compression index and applied load. Although the soil self‐weight has little effect on the degree of consolidation in some cases, the soil settlement will be significantly overestimated if the self‐weight is ignored. The development of consolidation slowed as the ratio of compressibility over horizontal permeability increased.

Section: Basic Assumptionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Large‐strain consolidation of PVD‐improved soils considering depth‐dependent initial void ratio and initial effective stress due to soil self‐weight

Tian,

Wu,

Wang

et al. 2023

Self Cite

“…Several analytical models of vacuum consolidation have been proposed, and the analytical theories are mainly based on the classical analytical models of sand drain consolidation 24,25,26,27,28,29 . Mohamedelhassan and Shang 30 indicated that the vacuum pressure can be treated as vertical pressure when establishing the analytical models of vacuum consolidation.…”

Section: Introductionmentioning

confidence: 99%

“…23 Several analytical models of vacuum consolidation have been proposed, and the analytical theories are mainly based on the classical analytical models of sand drain consolidation. 24,25,26,27,28,29 Mohamedelhassan and Shang 30 indicated that the vacuum pressure can be treated as vertical pressure when establishing the analytical models of vacuum consolidation. Zhou et al 31 established an analytical model for the axisymmetric consolidation of soft soil under a surcharge and vacuum preloading, and analytical solutions for a multi-layer soil system were then obtained.…”

Section: Introductionmentioning

confidence: 99%

Analytical solutions for consolidation of soft soil improved by air‐boosted vacuum preloading considering clogging effect

Sun

2023

Air‐boosted vacuum preloading is a newly emerging soft soil‐improving technology and increasingly draws attention of researchers and engineers. However, few analytical theories are available in the literature to facilitate the design and calculation of it in practice. To fill this gap, an analytical model for the consolidation of soft ground improved by air‐boosted vacuum preloading is proposed based on the assumption of equal volumetric strain and Darcy's law. Moreover, a time‐dependent clogging effect is taken into consideration to describe the gradual reduction in the drainage capacity of prefabricated vertical drains (PVDs) during the consolidation process. In addition, the smear effect is also considered due to the installation of PVDs. An air booster pipe and the surrounding PVDs are introduced into the unit cell for analysis based on the principle of equal cross‐sectional area, and analytical solutions under two typical time‐dependent horizontal loading are then developed. A comparison is made with the existing analytical model of conventional vacuum consolidation, which indicates that air‐boosted vacuum preloading can promote the consolidation of soft soil more effectively than conventional vacuum preloading. Furthermore, the obtained solution under instantaneously loading is used to investigate the influence of several parameters on consolidation behavior. Finally, to verify the accuracy of the analytical model with or without clogging effect, a comparative study is carried out with a field test.

Semi‐analytical solution for double‐layered elliptical cylindrical foundation model improved by prefabricated vertical drains

Zhao,

Guo,

Cao

et al. 2024

This work proposes a semi‐analytical solution for a double‐layered elliptical cylindrical soft foundation improved by prefabricated vertical drains. The governing equations, continuity conditions are boundary conditions in the elliptical cylindrical system are introduced first. The Laplace transform is employed to convert the time variable t in partial differential equations into the Laplace complex argument s. Based on the boundary condition and continuity condition, the solution in the frequency domain is derived. By using Abate's fixed Euler Algorithm, the solutions in the time domain are obtained. A finite element analysis is performed to demonstrate the accuracy of the proposed solution. Then, parametric studies reveal that soil permeability and soil compressibility have great influences on the second layer of soil in the elliptical cylindrical system, but relatively small effects on the first layer. Neglecting differences in the hydraulic conductivity and the coefficient of volume compressibility of multi‐layered soil in the elliptical cylindrical system could not predict the excess pore pressure in the second layer correctly.