Determination of Coefficients of Groundwater Flow in Multilayered Aquifers

It is difficult to determine the coefficients of groundwater flow from the data which were obtained from the drawdown test in a multiaquifer system. In this paper, new methods of analyzing drawdown-tests are developed and illustrated with the example to determine aquifer coefficients. In a double-layered aquifer, the analytical solution of drawdown test, in which water is discharged from both layers, is derived. And also the theoretical solution to determine the coefficient of storage by using an index of elasticity of a confined aquifer is derived. From these solutions, methods of determining the coefficient of transmissibility in a double-layered aquifer and the coefficinent of storage in a confined aquifer are got. The example analysis to determine aquifer coefficients is shown. As a result, the characteristics which were obtained by these methods are verified by the real drawdown test data

Prediction of Shrinkage and Creep of Concrete

New prediction equations of shrinkage and creep of concrete are proposed, and the efficiency of the new equations are investigated through a number of experimental data. Furthermore,the characteristics and applications of the prediction equations presented in the codes of many countries are also discussed. The results showing that the new equations could estimate shrinkage and creep of concrete within a certain measure of accuracy were obtained

Evaluation of closed-form analytical models for predicting unsaturated soil hydraulic properties

Knowledge of the unsaturated soil hydraulic properties is essential requirement for prediction of seepage flow and contaminant transport through the vadose zone. Unfortunately, these parameters are usually time consuming and expensive to measure in the field and laboratory. At the present condition, there are few data accumulation for Japanese soils. In this paper, van Genuchten's closed-form expressions are described to estimate unsaturated soil hydraulic properties. To evaluate the adequacy of these expressions, comparisons are performed between observed and calculated unsaturated hydraulic properties for typical Japanese soils

Finite Element Analysis of Salt Water Intrusion in Nonsteady Seepage

In this paper are described on the finite element analysis of the nonsteady behavior of interface between salt- and freshwater in coastal groundwater. In order to investigate the validity and the accuracy of this numerical analysis solution, the results calculated by this finite element analysis have been compared with the laboratory model tests. The numerical results showed the very good agreement with the experimental data. Moreover, some applications of this analytical method have been performed

Determination of Diffusion and Dispersion Parameters for Flow in Porous Media

The purposes of this research is an investigation of the intrusion of sea water into coastal aquifers. For this subject, this paper deals with proposing rational methods of getting diffusion coefficient and dispersion parameter for flow in porous media in a laboratory. These parameters of soil are indispensable in order to apply an analytical approach or a numerical approach to actual salt water intrusion problems. Experimental apparatuses were constructed and test procedures were also developed to measure concentration behaviors in a saturated porous media by using electro conductivity probe. As the results, the diffusion coefficients for the Toyoura standard sand and the Asahi river sand determined by two methods, that is, "Boltzman's transformation method" and "Instantaneous profile analysis method". The longitudinal coefficient of dispersion for one-dimensional flow was also determined by the least squares curve fitting method with a function of a certain range of seepage velocity

Numerical Analysis of Salt Intrusion into Aquifer by Eulerian Lagrangian Finite Element Method

In this paper, method of Eulerian Lagrangian numerical analysis is used to described Advection-Dispersion phenomena. The influence of concentration to the density of fluid is considered. A laboratory model of a two dimensional confined aquifer containing an isotropic, homogeneous porous medium (Hosokawa et.al 1989) was used to validate the applicability of Advection-Dispersion of numerical analysis with steady and unsteady state condition [1]

Analysis of the Variation of Unconfined Ground-Water Level Due to the Change of Water Level in a Surface Reservoir

In this paper, an analytical method is proposed for calculating the variation of unconfined ground-water level in steady state due to the change of water level in a lake or a river and presents some examples which deal with the variation of ground-water level in the southeast alluvial plain of Lake Biwa. In most alluvial plains, the compositions of the strata are so complicated that the depth, the permeability and the ground-water flow can not be surveyed continuously. Then even if some pumping tests and some observations of ground-water level are carried out, it is very difficult or almost impossible to comprehend the behaviors and to calculate the variation accurately by means of a normal treatment. Authors propose to adopt the conception “quasi-depth” which means the permeable capacity into this analytical method. Only the “quasi-depth” is variable and the other elements can be treated as constant factors in analyzing the variation of ground-water level numerically and graphically. The most advantageous point for using the “quasi-depth” in this method is that it is not necessary to measure the depth and the permeability continuously except for the depth at any selected point along a longitudinal section

Determination of Clay Minerals by the Ignition Loss MethodUsing a Muffle Furnace

A technique for determining the layer structure and content of clay minerals was developed based on the relationship between temperature, and moisture characteristics of clay minerals. Moisture content in standard specimens, prepared by mixing montmorillonite, kaolinite and quartz in various proportions, was determined by measuring weight loss after heating. Based on the results from differential thermal analysis tests, the ignition loss method was found to be widely applicable to clays with montmorillonite and kaolinite as the main components. Dehydration of constituent water occurred at 530℃ and 800℃ in two- and three-layered clay minerals, respectively

Determination of Unsaturated Soil Hydraulic Properties by Transient Flow Experiments and Parameter Estimation

The numerical feasibility of determining soil water retention and hydraulic conductivity functions simultaneously from one-dimensional transient flow experiments in the laboratory by parameter estimation method is evaluated. Soil hydraulic properties are assumed to be represented by van Genuchten's closed-form expressions involving two unknown parameters: coefficients α and n . These parameters are evaluated by nonlinear least-squares fitting of predicted and observed pressure head with time. Gravity drainage experiments are performed for Toyoura standard sand to evaluate the adequacy of this proposed method