Search

A tractable analytical solution for steady-state two-dimensional seepage from a trapezoidal channel in a homogeneous, isotropic porous medium of considerable depth is presented. The analysi...

Suction buckets are becoming established as a viable foundation solution for offshore wind turbines. In sand, suction-induced seepage flow reduces effective stresses at the skirt tips, whic...

As a typical form of internal erosion, suffusion refers to the detachment and migration of fine particles through voids among coarse particles driven by seepage flow. This paper studies the...

High groundwater flow velocity is a major challenge in many artificial ground freezing (AGF) projects, especially in groundwater control projects. That condition may be unfavorable for the ...

Sediment transport is a geophysical phenomenon in which sediment particles are driven to move in streamwise and vertical directions by various forces. Almost all existing formulas of sedime...

The two-dimensional unsteady confined-seepage flow through nonhomogeneous and anisotropic soils is studied in this paper. The study was based on a novel semianalytical method called scaled-...

Suffusion is a selective erosion of fine particles under the effect of seepage flow within the matrix of coarser particles. This complex phenomenon appears as a combination of three process...

Internal erosion involves selective loss of fine particles within the matrix of coarse soil particles under seepage flow, which affects the hydraulic and mechanical behavior of the soil. In this research, extensive laboratory internal erosion tests were conducted under complex stress states following three stress paths: isotropic, drained triaxial compression, and triaxial extension stress paths. These tests were designed to investigate the initiation and development of internal erosion and the effect of stress state on critical hydraulic gradients. The entire erosion process can be divided into four phases: stable, initiation, development, and failure. Accordingly, three critical gradients termed as initiation, skeleton-deformation, and failure hydraulic gradients, can be defined. These critical gradients correspond to the onset of erosion of the fine particles filling the large pores of the skeleton, the buckling of the strong force chains formed by the coarse particles, and the soil failure, re...

The sheet piles are used below hydraulic structures to reduce seepage flow rate and hydraulic gradients at the outlet of such structures that are rested on the permeable foundations. Up to now, for analysis of seepage under hydraulic structures, a number of research works have been conducted in the form of numerical models. However, less field and laboratory works have been done to study the boiling phenomenon for the evaluation of the numerical models. In the present research work, a laboratory model was made to simulate seepage flow and its behavior downstream of a sheet pile under vertical and inclined configurations. The model consisted of a flume 2.2 m long, 0.8 m deep, and 0.4 m wide, in which vertical and inclined sheet piles were provided by cast acrylic sheet. The flume was made of steel frame and Perspex as well as thick glass sheets. Fine clean sand was used as an alluvial foundation and then compacted to a uniform density at the bottom of 40 cm of flume. Perspex sheets were used as she...

Suffusion occurs when soil particles are loosened, detached, and transported away by seepage flow through a series of pores and pore constrictions. While traditional suffusion assessment methods are often based on particle size distribution analysis only, modern assessment methods are focused on constriction size distributions, which are derived from particle size distributions based on certain assumptions. This paper provides a new assessment method, which employs the probability of loose particles being transported to the next pore. The new approach can introduce the influence of an overlapping zone between the two fractions of loose particles and soil primary fabric. This overlapping zone was often overlooked in prior studies. The constriction size distribution of the primary fabric can be calculated approximately by two-dimensional or three-dimensional methods. The three-dimensional method used in the presented study even offers the opportunity to study the influence of particle arrangements on suffusion. The results of the new assessment methods show satisfactory agreement with experimental results.

Analytical solutions exist for the problem of determination of seepage loss from polygonal sections such as a triangle, a rectangle, and a trapezoid. In this investigation, seepage from circular and exponential sections has been calculated by a finite-difference-based numerical solution of the differential equation governing the seepage flow. The phreatic boundaries of the flow domain were described in terms of two parameters that are estimated by a minimization process. Such seepage computations were performed for a large number of independent dimensionless variables of the section geometry. Subjecting the computed seepage to regression analyses explicit equations for seepage loss from canals having circular and exponential cross sections have been obtained. Using these seepage-loss equations, the design variables for minimum seepage loss of circular and exponential canal sections have been obtained. The use of the design equations has been illustrated by design examples.

Transient, three-dimensional flux equations are solved by neglecting capillary forces in the first half of the paper, and in the second the steady-state seepage, where the capillary forces are significant, is treated. The following conclusions can be drawn by analysis of solutions for the cases of no capillary effects in unsaturated, anisotropic, layered slopes: (1) The seepage flow for these cases depends on the anisotropy of the soil. It further depends on the slope of the principal axis of the conductivity tensor. The seepage flow is completely independent of the slope of the soil surface. These findings make possible a new description of lateral flow mechanisms in slopes. Thus, the surprising result is that soil can possess a kind of “hydrological memory.” This is because the conductivity tensor can stay unchanged while the soil surface is altered. (2) Based on these findings, when a land fill cover is being designed, it is possible to obtain an optimal angle to minimize infiltration. Solutions for th...

The wave‐induced seepage flow in a porous seabed in the neighborhood of a gravity structure is solved exactly by two‐dimensional potential flow theory. The distribution of the hydrodynamic pore‐water pressure along the base of the structure and the wave‐induced vertical force on the structure are computed from the integral solutions. The effects of the thickness of the porous seabed and the width of the structure are examined. Results obtained from the exact theory are compared with experimental data and there is reasonable agreement.

Surficial failures are quite common and are caused by a reduction in shear strength due to saturation and swell coupled with a condition of seepage parallel to the slope face. An equation relating factor of safety to depth of seepage flow is used to investigate the surficial instability of compacted clays. The major unknowns in this equation are the drained strength parameters (ϕ′, C′) and depth of seepage flow. It is concluded that surficial stability evaluations, which are commonly performed in a fashion similar to that prescribed by Los Angeles County, may result in an overestimation of the factor of safety. The reason is that, for the tested clays, the effective cohesion intercept for gross stability is not appropriate for surficial stability analysis since it is an extrapolated value which is much greater than actual cohesion at low effective stresses.

Two-dimensional problem of steady seepage flow under gravity from system of parallel, identical, and equally spaced canals into semipervious clay layer underlain by freely permeable layer of sand and gravel in which piezometric heat is very near canal water level; two steps of conformal mapping are used and approximation to canal profile is adopted.

The effect of effluent and influent seepage on the hydrodynamic forces acting on an idealized noncohesive sediment particle are investigated experimentally. The hydrodynamic conditions near and within the porous medium of the channel bed are simulated through the use of shear-velocity Reynolds number and seepage Reynolds number. Drag and lift forces on a sediment particle are measured by a force dynamometer with and without the effects of effluent or influent seepage flow. The results are presented in the form of drag and lift coefficients as functions of shear-velocity Reynolds number for different effluent or influent seepage Reynolds numbers. The effects of seepage on the dynamic forces acting on a sediment particle are analyzed in an attempt to explain the observed experimental results.

The two-dimensional problem of unsteady seepage flow through a confined sand bed of vast plan area is attempted on mathematical lines. The treatment it applied to the ground water reservoir lying under the vast African Sahara Desert with the object of determining the amount of recharge to this aquifer as well as the amount of its storage. Resulting from the mathematical theory derived herein, the future ground water discharges of two main oases in Egypt (namely Kharga and Dakhla) have been predicted, till the year 2000. It is found that the free flow discharge of Kharga Oasis at present can irrigate a cultivated area of about 10,000 acres, the corresponding area of Dakhla Oasis being 22,000 acres. The installation of pumps in Kharga wells increases their discharge by about 15% and those of Dakhla by about 7% only. Owing to various complications in the pump installation, and the low water gain obtained by them, pumps should not be used. Their expenses far exceed the water gain secured by them.

The dispersion of a pollutant solution in a flow through a porous medium was investigated. A theoretical solution was obtained for the general, two-dimensional, convective-dispersion equation that describes the dispersion of a miscible, second fluid through a seepage flow. Application of the theoretical results requires knowledge of the basic seepage flow, the pollutant (second fluid) source concentration, and the longitudinal and lateral dispersion coefficients of the porous medium. A simplified theory and experiments were conducted to determine the coefficients. Their values found in the present study are in agreement with previously published results. Theoretical and experimental breakthrough curves for the general theory are presented and appropriate comparisons made. The unsteady growth of the dispersion front is shown, and the significant effects of both the longitudinal and lateral dispersion phenomena are clearly demonstrated.

Paper discusses saturation of agricultural soil by over-irrigation or rain; downward seepage flow through porous soil to system of parallel tile drains is studied, and theory of hydrodynamics is de...

Paper discusses saturation of agricultural soil by over-irrigation or rain; downward seepage flow through porous soil to system of parallel tile drains is studied, and theory of hydrodynamics is developed for providing scientific basis for design; new spacing formula is obtained based on time variation of water table; effect of evaporation from soil surface on spacing formula.

A new method of numerical solution of equations governing seepage flow, in non-homogeneous and anisotropic media is presented. The formulation is developed in some detail for two dimensional situations. In this, the region is divided into finite elements of triangular shape but of an arbitrary size. To each element different values of the two permeability coefficients and inclination of strata can be assigned at will in the computer program written. The solution is tested against a simple case of anisotropi seepage for which exact values are known and the accuracy obtained is excellent. The method is applied to obtain a solution to a hypothetical problem of some complexity in which the strata inclination varies from point to point together with the various values permeabilities. The method has obviously a general applicability to related problems such as torsion of anisotropic sections, etc. The basic flow theory in anisotropic materials is reviewed.

A general method is presented to calculate the seepage discharge from a channel of a complex shape. The method is based on use of Hadamard's formula for the variation of the Green's function when the shape of the region for which the Green's function is known has changed. The method is applied to calculate the seepage from channels of a complex shape that may be considered almost trapezoidal (or triangular). A simple geometrical construction yields the trapezoidal (or triangular) equivalent channel from which the same quantity of water is lost. Graphs of seepage discharge in dimensionless form are given for trapezoidal and triangular channels.

This paper deals with the two-dimensional problem of steady seepage flow under gravity from a canal into a semi-pervious clay layer of finite thickness underlain by a freely permeable layer of sand and gravel in which the piezometric head is very near the canal water level. Two steps of conformal mapping are used and an approximation to the canal profile is adopted. In this approximation the specified canal width and depth are untouched.