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The destruction of marine soft clays' macropore structure results in large-strain deformation during consolidation, as well as the potential to alter rheological deformation characteristics. A sectionalised regimes rheological model was adopted to describe the structural characteristics under the isotache framework, which led to a nonlinear variation of geometrical boundaries and material properties during consolidation. A semi-analytical theory combining numerical and analytical methods was developed, and the solutions for excess pore water pressure, degree of consolidation, and settlement were derived and computationally programmed. Using parametric analysis, the effects of rheological and structural characteristics on the consolidation behaviour of soft clay were discussed compared to the solutions of other theories. The coefficient of secondary consolidation in the transitional regime has an impact beginning in the middle of primary consolidation. The proposed solutions for degree of consolidation are smaller than the small-strain solutions during the early period of primary consolidation but change larger as consolidation progresses. [ABSTRACT FROM AUTHOR]

The dynamic response of an offshore pile in saturated soil subjected to lateral harmonic loading is theoretically investigated by considering the dynamic pile-water interaction. The governing equation of water is solved based on the separation of variable method, and the analytical expression of the hydrodynamic force applied on the pile is then obtained. Based on the continuous conditions at the pile-soil interface and pile-water interface, the analytical solution of the dynamic impedance of the offshore pile is derived by using transfer matrix method. To verify this solution, the dynamic impedance obtained for a cylinder in water is compared with that of a partially embedded pile. Based on this solution, the effect of hydrodynamic pressure and other parameters on the dynamic response of offshore piles is investigated. The results show that the analytical model ignoring the hydrodynamic force applied on the pile misestimates the impedance of the pile in the high frequency range. [ABSTRACT FROM AUTHOR]

Summary: In recent years, a new technique of ground improvement, which involves the combined use of impervious column and vertical drains, has been proposed and utilized in many field projects to accelerate consolidation and increase bearing capacity of soft soil ground. To cover the possible distribution patterns of impervious columns and vertical drains, 2 analytical models, including Model A with outward flow and Model B with inward flow within the soils, are proposed to predict the consolidation of combined composite ground by considering the following factors: (1) disturbance effects of both impervious columns and vertical drains, (2) the well resistance of vertical drains, and (3) time‐variant loadings. The average degrees of consolidation predicted by the proposed analytical models are compared with several existing solutions and then against the measured data in the literature. The consolidation behavior of a combined composite ground is investigated by the proposed analytical solutions. The results show that the combined use of impervious columns and vertical drains can remarkably accelerate the consolidation rate of soft soils compared with the single use of either of them. The average degrees of consolidation predicted by both analytical models agree well with the measured data. Compared with Model B, Model A usually predicts a faster consolidation rate because of a shorter drainage path. Many factors can influence consolidation behavior of combined composite ground, such as loading scheme, distribution patterns and the disturbance effects of impervious columns and vertical drains, and compression modulus ratio of impervious column to soil. [ABSTRACT FROM AUTHOR]

Pore water and earth pressures acting on retaining structures are investigated using an efficient coastal double-layered excavation model to determine offshore excavation responses to groundwater fluctuations outside foundation pits. Total pore water pressure includes excess pore water pressure (due to groundwater fluctuations) and steady pore water pressure (due to steady seepage) determined using one-dimensional consolidation theory of double-layered soil and one-dimensional steady-state flow theory, respectively. Rankine's active and passive earth pressures are obtained from pore water pressure. This method is applicable to arbitrary groundwater fluctuation conditions. How physical parameters affect pore water pressure is numerically investigated using examples, demonstrating the method's practicality for calculating pore water and earth pressures. [ABSTRACT FROM PUBLISHER]

Various analytical theories of consolidation for soils with vertical drains have been proposed in the past. Most conventional theories are based on a cylindrical unit cell that contains only a single vertical drain. This paper described a new analytical model where a vertical drain located at the centre (the 'inner vertical drain') and is surrounded by two or three vertical drains (the 'outer vertical drains'), the number of which depends on whether the configuration is triangular or rectangular. Both types of drains are combined into a cylindrical unit cell, and the water is assumed to flow both inwards to the inner vertical drain and outwards to the outer vertical drains distributed around the circumference. The outer radial boundary of the unit cell is regarded as a permeable boundary, with a drainage capacity of two or three separate vertical drains for triangular and rectangular configurations, respectively. The smear effects and the drainage resistances for both the inner and outer vertical drains are considered in the analysis as well. In this way, the equations governing the consolidation process with multiple vertical drains are derived, and the corresponding analytical solutions are obtained for instantaneously loading, ramp loading and multi-stage of instantaneously loading and multi-stage of ramp loading. The present solutions are finally compared with several conventional solutions for a single vertical drain in the literature. The results show that the present model predicts the same average degree of consolidation as conventional models do, which verifies the correctness of this new model. Finally, the settlement predicted by the present solution is compared with the measured settlement from a field test at the Port of Brisbane, Australia, which shows a good agreement between them. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Analytical solutions are developed for one-dimensional consolidation of double-layered saturated soil subjected to groundwater fluctuations. The solutions are derived by an explicit mathematical procedure using Duhamel’s theorem in conjunction with a Fourier series, when groundwater fluctuation is described by a general time-dependent function and assumed to be the pore water pressure variations at the upper boundary. Taking as an example the harmonic groundwater fluctuation, the relevant response of the excess pore water pressure is discussed in detail, and the main influencing factors of the excess pore pressure distribution are analyzed. A dimensionless parameter θ has been introduced because it significantly affects the phase and the amplitude of excess pore pressures. The influences of the coefficients of permeability and compressibility of soil on the excess pore pressure distribution are different and cannot be incorporated into the coefficient of consolidation in double-layered soil. The relative permeability ratio of two clayey soils also plays an important role on the curves of the distributions of the excess pore pressures. The effects of the thickness of the soil layer on the excess pore pressure distribution should be considered together with the dimensionless parameter θ and the permeability and compressibility of the double-layered soil system. [ABSTRACT FROM AUTHOR]

SUMMARY By incorporating the nonlinear variation of a soil's compressibility and permeability during the process of consolidation, an analytical solution for the radial consolidation of vertical drains has been developed for a general time-variable loading. The general solution was verified for the cases of instantaneous loading and ramp loading. Detailed solutions were further derived for two special loading schemes: multistage loading and preloading-unloading-reloading. The nonlinear consolidation behavior of a vertical drain subjected to these two types of loading schemes was then investigated by a parametric study. The results show that the loading rate, the ratio of the compressibility index to the permeability index ( Cc/ Ck), and the initial stress state have a significant influence on the consolidation rate. A smaller value of Cc/ Ck, a larger initial stress, or a fast loading rate always leads to a rapid consolidation rate. During the unloading period, a negative excess pore water pressure may occur, and a slower unloading rate may reduce this negative value. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an attempt has been made to investigate the thermo-hydro-elastodynamic response of a spherical cavity in isotropic saturated poroelastic medium when subjected to a time dependent thermal/mechanical source. The fully coupling thermo-hydro-elastodynamic model is presented on the basis of equations of motion, fluid flow, feat flow and constitutive equation with effective stress and temperature change. Solutions of displacement, temperature and stresses are obtained by using a semi-analytical approach in the domain of Laplace transform. Numerical results are also performed for portraying the nature of variations of the field variables, i.e. the coefficient of thermo-osmosis, the permeability. In addition, comparisons are presented with the corresponding partially thermo-hydro-elastodynamic model and thermo-elastodynamic model to ascertain the validity and the difference between these models. [Copyright &y& Elsevier]

Abstract: The thermo-hydro-elastodynamic model (THED), in which the thermo-osmosis and thermal-filtration phenomenon in a two-phase porous thermoelastic medium can be considered, was previously presented by the authors [Ganbin Liu, Kanghe Xie, Rongyue Zheng. Model of nonlinear coupled thermo-hydro-elastodynamics response for a saturated poroelastic medium. Sci China (Ser E) 2009;52(8):2373–83] and is used in this paper to investigate the thermo-elastodynamic response of a spherical cavity in a saturated poroelastic medium when subjected to a time-dependent non-torsional thermal/mechanical source. The Separated Variable Method is introduced, and the non-zero displacement potentials are expanded in terms of the Legendre polynomial. Solutions for the displacement, temperature increment, pore pressure and stress are obtained in the domain of the Laplace transform. Numerical results are also performed for different modes and are compared with the results of the thermoelastic model (TED) to ascertain the validity and the difference between these two models. [Copyright &y& Elsevier]

An improved model is developed to analyze the horizontal dynamic response of piles in saturated soil. The proposed model retains the simplicity of the plane strain model while accounting for 3-D effects. The vertical coordinate is suppressed by integrating the governing equations over the length of the pile. The three-dimensional model is reduced to a simpler model that is similar to the plane strain model. Explicit closed-form solutions are obtained by introducing potential functions. The proposed model is verified by comparison with more rigorous solutions. Finally, the influence of pile slenderness, permeability of soil, and other parameters on dynamic soil reaction and dynamic response of pile is investigated. It is revealed that the proposed model avoids the drawbacks of the earlier model and is effective in predicting the horizontal dynamic response of the pile. [ABSTRACT FROM AUTHOR]

Electro-osmosis (EO) can be used to rapidly treat large areas of dredged slurry. At present, the theory of electro-osmosis consolidation (EOC) needs to be further developed to fit actual dredged slurry treatment scenarios. In this study, governing equations of EOC considering the large deformation constitutive relationship were derived with excess pore water pressure (EPWP) as a variable, and a concise EOC model was established for dredged slurry. Together with boundary conditions and initial conditions, the numerical method was adopted to obtain the finite difference solution for the EOC model. Then, EO experiments with different voltage stages were conducted using a self-designed and large-diameter EOC device, where the variations in current, drainage volume, EPWP, water content and vane shear strength were measured. Moreover, the phenomena of soil cracks, heat release, and electrode corrosion as well as the formation of Fe(OH) 3 were recorded during the EO process. Additionally, nonlinear variation laws for effective stress, hydraulic permeability coefficient (HPC) and electro-osmosis permeability coefficient (EOPC) with void ratio of dredged slurry were obtained through indoor tests, in which a self-designed device for testing EOPC was used. Finally, the correctness of the proposed EOC model was verified by comparison with the results of the experiments and Esrig's analytical solution considering the small-strain constitutive relationship, where the consolidation characteristics were analyzed. In conclusion, the large deformation EOC model deduced in this paper could provide a more accurate prediction of the consolidation behavior of dredged slurry. • An innovative vertical electro-osmosis consolidation model. • Consideration of the nonlinear variations of soil properties in the model. • Electro-osmosis experiment using a self-designed large-diameter indoor device. • Electro-osmosis permeability coefficient test using a self-designed device. • Constructive suggestions of graded voltage electro-osmosis treating dredged slurry. [ABSTRACT FROM AUTHOR]

The consolidation behavior of ground with vertical drains is known to be greatly affected by the finite permeability of the sand drains, also called the effect of well resistance. However, up to now, no analytical methods have been reported for evaluating this effect on the nonlinear consolidation behavior of vertical drains. In this paper, by considering the nonlinear compressibility and permeability of soil during consolidation, the effect of well resistance was incorporated into the derivation of the equations that govern the nonlinear consolidation of a vertical drain with coupled radial–vertical flow. In addition, the smear effect was considered by assuming three decay patterns for the radial permeability coefficients of the soil toward the sand drain in the smeared zone. After obtaining the governing equations, a simplified analytical solution is derived for a general time-variable surcharge loading. Based on the general solution obtained, detailed solutions are provided for three special types of loading schemes: constant loading, single-stage loading, and multi-stage loading. The validity of the solution is verified by reducing it to several special cases and comparing these to existing solutions. Finally, the effect of the well resistance, the ratios of the compression index to the radial and vertical permeability indices, various loading schemes, and various variation patterns of the radial permeability coefficient of the soil in the smeared soil zone are investigated using parametric analysis. [ABSTRACT FROM AUTHOR]

Abstract: A comprehensive analytical solution is developed in this paper to investigate the torsional vibration of an end bearing pile embedded in a homogeneous poroelastic medium and subjected to a time-harmonic torsional loading. The poroelastic medium is modeled using Biot’s two-phased linear theory and the pile using one-dimensional elastic theory. By using the separation of variables technique, the torsional response of the soil layer is solved first. Then based on perfect contact between the pile and soil, the dynamic response of the pile is obtained in a closed form. Numerical results for torsional impedance of the soil layer are presented first to portray the influence of wave modes, slenderness ratio, pile–soil modulus ratio and poroelastic properties. A comparison with the plane strain theory is performed. The selected numerical results are obtained to analyze the influence of the major parameters on the torsional impedance at the level of the pile head. Finally, the dynamic torsional impedance of this study is compared with that for floating pile in elastic soil. [Copyright &y& Elsevier]