An analytical solution is derived from the generalized governing equations of equal-strain consolidation with vertical drains under multi-ramp surcharge preloading. The hydraulic boundary conditions at both top and bo...An analytical solution is derived from the generalized governing equations of equal-strain consolidation with vertical drains under multi-ramp surcharge preloading. The hydraulic boundary conditions at both top and bottom of the consolidating soil are modelled as impeded drainage. The impeded drainage is described by using the third type boundary condition with a characteristic factor of drainage efficiency. Fully drained and undrained boundary conditions can also be modelled by applying an infinite and a zero characteristic factor, respectively. Simultaneous radial and vertical flow conditions are considered, together with the effects of drain resistance and smear. An increase in total stress due to multi-ramp loading is reasonably modelled as a function of both time and depth. A solution to calculate excess pore-water pressure at any arbitrary point in soil is derived, and the overall average degree of consolidation is obtained. It shows that the proposed solution can be used to analyze not only vertical-drain consolidation but also one-dimensional consolidation under either one-way or two-way vertical drainage conditions. The characteristic factors of drainage efficiency of top and bottom boundaries have a potentially important influence on consolidation. The boundary may be considered fully drained when the characteristic factor is greater than 100 and fully undrained when the characteristic factor is less than 0.1. The stress distribution along depth induced by the surcharge loading has a limited effect on the overall average degree of consolidation.展开更多
An analytical solution was presented to the unsaturated soil with a finite thickness under confinement in the lateral direction and sinusoidal cyclic loading in the vertical direction based on Fredlund's one-dimen...An analytical solution was presented to the unsaturated soil with a finite thickness under confinement in the lateral direction and sinusoidal cyclic loading in the vertical direction based on Fredlund's one-dimensional consolidation equation for unsaturated soil. The transfer relationship between the state vectors at the top surface and any depth was gained by applying the Laplace transform and Cayley-Hamilton mathematical methods to the governing equations of water and air, Darcy's law and Fick's law. The excess pore-air and pore-water pressures and settlement in the Laplace-transformed domain were obtained by using the Laplace transform with the initial and boundary conditions. The analytical solutions of the excess pore-air and pore-water pressures at any depth and settlement were obtained in the time domain by performing the inverse Laplace transforms. A typical example illustrates the consolidation characteristics of unsaturated soil under sinusoidal loading from analytical results. Finally, comparisons between the analytical solutions and results of the numerical method indicate that the analytical solution is correct.展开更多
The hierarchical BiOClxBr1–x was synthesized by a simple solvothermal method. The samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, UV-visible diffuse ref...The hierarchical BiOClxBr1–x was synthesized by a simple solvothermal method. The samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, UV-visible diffuse reflectance spectroscopy （UV-vis DRS） and Brunauer-Emmett-Teller adsorption method. Compared to pure BiOCl or BiOBr, the BiOClxBr1–x solid solution has enhanced photocatalytic degradation activity for rhodamine B. This phenomenon can be explained to the hierarchical structure, lager specific surface area and appropriate energy gap of the obtained BiOClxBr1–x solid solution. The renewability and stability of photocatalyst were determinated and a possible mechanism of photocatalytic degradation was also proposed.展开更多
In order to investigate the effects of freezing and thawing on the compressibility of fine-grained soils, freezing and thawing tests and subsequent compression tests with fine-grained soils in an oedometer were carrie...In order to investigate the effects of freezing and thawing on the compressibility of fine-grained soils, freezing and thawing tests and subsequent compression tests with fine-grained soils in an oedometer were carried out. During the freezing, a part of the soils is loosened and another part is over-consolidated under the freezing pressure σE. The compression curves after the freezing and thaw consolidation are neither different from the normal consolidation curve nor from the rebound curve of an unfrozen soil, until the consolidation pressure σz = σE is arrived. Based on the experimental results, a theoretical model has been devel- oped to predict the frost heaves, the thaw-settlements and the compressive deformations of fine-grained soils after the thaw consolidation. The theoretical results are very close to the experimental results.展开更多
In this paper,a semi-analytical method for the analysis of pile-supported embankments is proposed.The mathematic model describes the cooperative behavior of pile,pile cap,foundation soil,and embankment fills.Based on ...In this paper,a semi-analytical method for the analysis of pile-supported embankments is proposed.The mathematic model describes the cooperative behavior of pile,pile cap,foundation soil,and embankment fills.Based on Terzaghi's 1D consolidation theory of saturated soil,the consolidation of foundation soil is calculated.The embankments with two different types of piles:floating piles and end-bearing piles are investigated and discussed.The results of axial force and skin friction distributions along the pile and the settlements of pile-supported embankments are presented.It is found that it takes a longer time for soil consolidation in the embankment with floating piles,compared with the case using end-bearing piles.The differential settlement between the pile and surrounding soil at the pile top is larger for the embankment with end-bearing piles,compared with the case of floating piles.展开更多
基金Project(51278171)supported by the National Natural Science Foundation of ChinaProject(B13024)supported by Program of Introducing Talents of Discipline to Universities("111" Project),ChinaProject(2014B04914)supported by the Fundamental Research Funds for the Central Universities of China
文摘An analytical solution is derived from the generalized governing equations of equal-strain consolidation with vertical drains under multi-ramp surcharge preloading. The hydraulic boundary conditions at both top and bottom of the consolidating soil are modelled as impeded drainage. The impeded drainage is described by using the third type boundary condition with a characteristic factor of drainage efficiency. Fully drained and undrained boundary conditions can also be modelled by applying an infinite and a zero characteristic factor, respectively. Simultaneous radial and vertical flow conditions are considered, together with the effects of drain resistance and smear. An increase in total stress due to multi-ramp loading is reasonably modelled as a function of both time and depth. A solution to calculate excess pore-water pressure at any arbitrary point in soil is derived, and the overall average degree of consolidation is obtained. It shows that the proposed solution can be used to analyze not only vertical-drain consolidation but also one-dimensional consolidation under either one-way or two-way vertical drainage conditions. The characteristic factors of drainage efficiency of top and bottom boundaries have a potentially important influence on consolidation. The boundary may be considered fully drained when the characteristic factor is greater than 100 and fully undrained when the characteristic factor is less than 0.1. The stress distribution along depth induced by the surcharge loading has a limited effect on the overall average degree of consolidation.
基金Project(2010G016-B)supported by Science and Technology Research and Development of China
文摘An analytical solution was presented to the unsaturated soil with a finite thickness under confinement in the lateral direction and sinusoidal cyclic loading in the vertical direction based on Fredlund's one-dimensional consolidation equation for unsaturated soil. The transfer relationship between the state vectors at the top surface and any depth was gained by applying the Laplace transform and Cayley-Hamilton mathematical methods to the governing equations of water and air, Darcy's law and Fick's law. The excess pore-air and pore-water pressures and settlement in the Laplace-transformed domain were obtained by using the Laplace transform with the initial and boundary conditions. The analytical solutions of the excess pore-air and pore-water pressures at any depth and settlement were obtained in the time domain by performing the inverse Laplace transforms. A typical example illustrates the consolidation characteristics of unsaturated soil under sinusoidal loading from analytical results. Finally, comparisons between the analytical solutions and results of the numerical method indicate that the analytical solution is correct.
基金Project(2016TP1007)supported by the Hunan Provincial Science and Technology Plan Project,China
文摘The hierarchical BiOClxBr1–x was synthesized by a simple solvothermal method. The samples were characterized by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, UV-visible diffuse reflectance spectroscopy （UV-vis DRS） and Brunauer-Emmett-Teller adsorption method. Compared to pure BiOCl or BiOBr, the BiOClxBr1–x solid solution has enhanced photocatalytic degradation activity for rhodamine B. This phenomenon can be explained to the hierarchical structure, lager specific surface area and appropriate energy gap of the obtained BiOClxBr1–x solid solution. The renewability and stability of photocatalyst were determinated and a possible mechanism of photocatalytic degradation was also proposed.
文摘In order to investigate the effects of freezing and thawing on the compressibility of fine-grained soils, freezing and thawing tests and subsequent compression tests with fine-grained soils in an oedometer were carried out. During the freezing, a part of the soils is loosened and another part is over-consolidated under the freezing pressure σE. The compression curves after the freezing and thaw consolidation are neither different from the normal consolidation curve nor from the rebound curve of an unfrozen soil, until the consolidation pressure σz = σE is arrived. Based on the experimental results, a theoretical model has been devel- oped to predict the frost heaves, the thaw-settlements and the compressive deformations of fine-grained soils after the thaw consolidation. The theoretical results are very close to the experimental results.
基金Project supported by the Research Committee of the University of Macao (Nos. MYRG189(Y2-L3)-FST11-ZWH and MYRG067(Y1-L2)-FST12-ZWH),Macao SAR,China
文摘In this paper,a semi-analytical method for the analysis of pile-supported embankments is proposed.The mathematic model describes the cooperative behavior of pile,pile cap,foundation soil,and embankment fills.Based on Terzaghi's 1D consolidation theory of saturated soil,the consolidation of foundation soil is calculated.The embankments with two different types of piles:floating piles and end-bearing piles are investigated and discussed.The results of axial force and skin friction distributions along the pile and the settlements of pile-supported embankments are presented.It is found that it takes a longer time for soil consolidation in the embankment with floating piles,compared with the case using end-bearing piles.The differential settlement between the pile and surrounding soil at the pile top is larger for the embankment with end-bearing piles,compared with the case of floating piles.
