JaLCDOI 10.18926/15748
フルテキストURL Mem_Sch_Eng_OU_14_2_53.pdf
著者 Nishigaki Makoto| Kono Iichiro|
抄録 The purposes of this paper are primarily to research on behavior of groundwater flow in saturated and unsaturated zone, and to present the fundamentals of the theory of groundwater flow. This paper discusses the physics of the saturated-unsaturated groundwater motion. Evaluations confirm the early belief that Darcy's law is of the nature of statistical result giving the empirical equivalent of Navier-Stokes equations. The governing equation of saturated-unsaturated flow in porous media is derived from the law of mass conservation and from the Darcy's law and Richard's equation of motion and is compared with the Klute's diffusion equation which has been widely used in the analysis of unsaturated flow. As a result; it is concluded that the governing equation has the advantage that can be applied for the whole flow region. Typical boundary conditions are enumerated.
出版物タイトル Memoirs of the School of Engineering, Okayama University
発行日 1980-03-01
14巻
2号
開始ページ 53
終了ページ 72
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307170
JaLCDOI 10.18926/15463
フルテキストURL Mem_Fac_Eng_OU_28_2_59.pdf
著者 西垣 誠| Sun Yao| 河野 伊一郎|
抄録 In this paper, first, an elasto-plastic consitituve equation for unsaturated soil was developed by considering of the basically behavior of unsaturated soil. Second, the results of a number of triaxial test and a set of rigid foundation model tests were simulated by using this constitutive equation, the agreement between observed and computed results was satisfactory and confirms the possibilities of this constitutive equation.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1994-03-15
28巻
2号
開始ページ 59
終了ページ 75
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307850
JaLCDOI 10.18926/15398
フルテキストURL Mem_Fac_Eng_OU_27_1_93.pdf
著者 西垣 誠| Sudinda Teddy| Hishiya Tomoyuki| 河野 伊一郎|
抄録 In this paper the author will be describe phenomena of advection dispersion in subsurface flow by using Eulerian Lagrangian Finite Element Method. Where Finite Element Method with Galerkin formulation and weigthed residual method is used to solve seepage and advection dispersion equation. The problem of one dimensional and two dimensional rectangular wave are analyzed in this paper. And the result of numerical analyses will be compared with analytical solutions. The numerical results showed the very good agreement with the analytical solutions.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1992-11-25
27巻
1号
開始ページ 93
終了ページ 105
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307768
JaLCDOI 10.18926/15451
フルテキストURL Mem_Fac_Eng_OU_22_45.pdf
著者 河野 伊一郎| 西垣 誠| 竹下 祐二|
抄録 There are two classifications of the mechanism of levee failure caused by floods; local seepage failure and progressive failure. The fundamental causes of levee failure produced by piping and erosion were studied and the safety of river leves during floods evaluated in terms of soil machanics. The critical hydraulic gradient and the process of progressive failure were obtained from one- and two- dimensional model experiments for piping and erosion. Problems inherent in and preventive measures against levee failure are discussed. In particular, effects of the Tsukinowa method, the most representative Japanese flood fighting method, were studied experimentally and improvements proposed.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1988-03-31
22巻
開始ページ 45
終了ページ 62
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307536
JaLCDOI 10.18926/15731
フルテキストURL Mem_Sch_Eng_OU_12_97.pdf
著者 Kono Iichiro| Nishigaki Makoto|
抄録 The solutions of unsteady phreatic flow toward a partially penetrating well in an aquifer of finite thickness are described. Firstly the solution for a confined aquifer is shown. In this case,three methods of analyzing field data with partially penetrating well are given, that is, "Log-Log Method, Log-Log Distance Drawdown Method and Jacob's Method Ajusted for Partial Penetration". By using these methods the hydraulic conductivities and the specific storage of the aquifer may be determined. Secondly the solution for an,unconfined aquifer is shown. In this case, also two methods of analyzing field data with partially penetrating well are given. By using these methods, the anisotropic permeability and the storage coefficient (effective porosity) of the aquifer may be determined. Moreover in each case, the effects of partial penetration are discussed and the limits of adapting the Theis' and Jacob's methods are setted. From these analytic results, some cosiderations are added to determine the anisotropy of permeability and to evaluate the storage coefficient.
出版物タイトル Memoirs of the School of Engineering, Okayama University
発行日 1978-02-25
12巻
開始ページ 97
終了ページ 128
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307830
JaLCDOI 10.18926/15742
フルテキストURL Mem_Sch_Eng_OU_14_1_61.pdf
著者 Kono Iichiro| Nishigaki Makoto|
抄録 The purposes of this paper are primarily to research on behavior of groundwater flow in saturated and unsaturated zone and to develop the most effective methods for solving groundwater flow problems related to civil engineering practice. The mathematical model provides a finite element solution to two- or threedimensional problems involving transient flow in the saturated and unsaturated domains of nonhomogeneous, anisotropic porous media. Before progressing into the various levels of applications the input data and boundary conditions are discussed and evaluated. To demonstrate the flexibility of the finite element approach and its capability in treating complex situations which are often encountered in the field, the groundwater flow through sand bank at flood water levels and the flow through aquifer due to an excavation were analyzed. As the results there were good qualitative agreements between the numerical results and the informations received.
出版物タイトル Memoirs of the School of Engineering, Okayama University
発行日 1979-12-01
14巻
1号
開始ページ 61
終了ページ 94
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307580
JaLCDOI 10.18926/fest/11598
フルテキストURL 002_025_032.pdf
著者 西垣 誠| Schreck Martin|
抄録 Engineers have long sought the possibility of measuring parameters such as temperature and pressure continuously in the underground with high precision, high spatial resolution and high band width of parameters. Distributed fibre optic measurement offers the use of a very fast, robust, precise, light and small gauges with an high spatial resolution. In this paper we would like to compile fibre-optic measure-methods which are available now for projects in geohydraulical engineering. This paper will propose new problems for future research work on parameter identification for such parameters as conductivity and anisotropy.
出版物タイトル 岡山大学環境理工学部研究報告
発行日 1997-01-10
2巻
1号
開始ページ 25
終了ページ 32
ISSN 1341-9099
言語 英語
論文のバージョン publisher
NAID 120002313718
JaLCDOI 10.18926/fest/15044
フルテキストURL 014_017_022.pdf
著者 Akudago John Apambilla| 西垣 誠| Chegbeleh Larry Pax| 小松 満| Alim Md. Abdul|
抄録 Soil-groundwater salinity issues have assumed a worldwide dimension. It is believed that when groundwater level is less than 2 m there is the possibility of salinity transfer between the soil and groundwater due to factors such as capillary forces. One-dimensional column tests were conducted in the laboratory to find a suitable capillary cut design. The capillary cut material comprised a 20 cm thick 2–4.7 mm and a combination of 2–4.7 mm and 9.5–19 mm gravel material. In all, four different designs were tested by compacting Oji sand in the various columns. Groundwater level of 0.75 m from the top was maintained while salt solution of 10% concentration was allowed to flow under capillary forces through the columns. The water content in the columns were monitored using frequency domain reflectrometry-vector analyzer (FDR-V) after which soil samples from 10 m interval in each column was taken for electrical conductivity measurements. The results showed that 5 cm thick, 2–4.7 mm gravel sandwiching coarser material (e.g. 5 cm thick 9.5–19 mm or 10 cm thick 9.5–19 mm gravel material) proved to be very useful design to cut capillarity.
キーワード soil-groundwater salinity capillary cut filter media design
出版物タイトル 岡山大学環境理工学部研究報告
発行日 2009-03-16
14巻
1号
開始ページ 17
終了ページ 22
ISSN 1341-9099
言語 英語
論文のバージョン publisher
NAID 120002308001
JaLCDOI 10.18926/fest/12814
フルテキストURL 13_001_005.pdf
著者 Chegbeleh Larry Pax| 西垣 誠| Akudago John Apambilla| Alim Md. Abdul| 小松 満|
抄録 In an effort to secure the comfort of all aspect of life and security through electricity production, research, nuclear weapons production and medical uses, radioactive waste is being generated throughout the world as a result. Without pro – active management and protection, the hazardous nature of radioactive materials can pose serious threats to human health and the environment. A waste containment or disposal facility is required to isolate the waste from man and the biosphere to avoid any undue radiation exposure. Deep geological repository or disposal facility is considered as an effective way to isolate high level radioactive waste, HLW from the human environment, for which a multi – barrier system plays a very significant role. In this paper, literature collection was carried out, aimed to overview the present knowledge about the concepts of repository for HLW and to identify technologies that are currently available in the nuclear industry worldwide and the current state of barrier technologies for hazardous waste sites.
キーワード repository bentonite radioactive waste swelling buffer and backfill materials
出版物タイトル 岡山大学環境理工学部研究報告
発行日 2008-03
13巻
1号
開始ページ 1
終了ページ 5
ISSN 1341-9099
言語 英語
論文のバージョン publisher
NAID 120002304817
JaLCDOI 10.18926/fest/11466
フルテキストURL 009_099_110.pdf
著者 Dewan A.M.| 西垣 誠| 小松 満|
抄録 Dhaka city, the capital of Bangladesh and home for more than 10 million people, has been affected by seasonal flooding almost in every year, however, the situation aggravates depending on rainfall and surrounding river waters. The aim of this paper is to delineate the flood extent in Dhaka city using digital elevation model (DEM), an integral part of geographic information system. Catastrophic floods of the 1988 and 1998 events are taken into consideration. Hydro-meteorological assessment of these events revealed that the 1988 flood was severe due to the lack of flood protection in the city together with transboundary flow of the major rivers while the 1998 flood was become deluge due to incessant monsoonal downpour along with early peaked of the river water levels. The 1998 event has done colossal damage in the city compare to the 1988 event. Flood extent estimation showed that DEM data is very precious to model inundation in the city, however, in order to be spatially explicit flood model, high resolution DEM is necessary. Finally, flood management issues are reviewed and found that combination of structural and nonstructural measures are necessary to help reducing flood induced losses and damage in the city.
キーワード Dhaka City Floods Digital Elevation Model 1998 and 1988 Floods
出版物タイトル 岡山大学環境理工学部研究報告
発行日 2004-02-27
9巻
1号
開始ページ 99
終了ページ 110
ISSN 1341-9099
言語 英語
論文のバージョン publisher
NAID 120002313678
JaLCDOI 10.18926/15835
フルテキストURL Mem_Sch_Eng_OU_21_1_71.pdf
著者 Takeshita Yuji| Nishigaki Makoto| Kohno Iichiro|
抄録 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.
出版物タイトル Memoirs of the School of Engineering, Okayama University
発行日 1986-11-15
21巻
1号
開始ページ 71
終了ページ 79
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307954
JaLCDOI 10.18926/15795
フルテキストURL Mem_Sch_Eng_OU_16_1_65.pdf
著者 Kohno Iichiro| Nishigaki Makoto|
抄録 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.
出版物タイトル Memoirs of the School of Engineering, Okayama University
発行日 1982-03-01
16巻
1号
開始ページ 65
終了ページ 89
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307205
JaLCDOI 10.18926/fest/15043
フルテキストURL 014_013_016.pdf
著者 Alim Md. Abdul| 西垣 誠| Chegbeleh Larry Pax| Akudago John Apambilla| 小松 満|
抄録 Soil-water characteristic curve (SWCC) is an important soil function in an unsaturated soil mechanics field for design and analyses of any unsaturated earth structures. Determination of SWCC is not easy and more so time consuming. Generally, ceramic disc with high air-entry value has been used in the pressure plate apparatus for this purpose by many people. Now-a-days membrane filter is being used as a suitable alternative to ceramic disc. However, experience shows, it has disadvantage of breakage after one time use especially with coarse grain soils (sandy soils). In this study, membrane filter with stainless wire mesh was used to solve this problem and the SWWC was compared with the results obtained without wire mesh. Results showed that membrane filter with stainless wire mesh can be used to determine the SWCC for coarse grain soils.
キーワード SWCC Unsaturated sandy soils Membrane filter Stainless wire mesh
出版物タイトル 岡山大学環境理工学部研究報告
発行日 2009-03-16
14巻
1号
開始ページ 13
終了ページ 16
ISSN 1341-9099
言語 英語
論文のバージョン publisher
NAID 120002307956
JaLCDOI 10.18926/15483
フルテキストURL Mem_Fac_Eng_OU_24_1_107.pdf
著者 河野 伊一郎| 西垣 誠| 竹下 祐二|
抄録 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.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1989-11-29
24巻
1号
開始ページ 107
終了ページ 114
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307749
JaLCDOI 10.18926/15498
フルテキストURL Mem_Fac_Eng_OU_25_1_99.pdf
著者 西垣 誠| 竹下 祐二| 河野 伊一郎|
抄録 In this paper, a numerical procedure of determining hydraulic properties in multilayered aquifers are presented. From pumping test data in multilayered aquifers, the coefficient of permeability and specific storage for each aquifer are determined by using a combination of finite element analysis and nonlinear least-squares optimization technique. This study especially points out necessity of stress-flow coupling analysis to explain the behaviors of pressure head in multilayered aquifer during pumping test. As a example, practical pumping test data were evaluate and the coefficients of permeability and specific storage of aquifers and aquitard were obtained.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1990-12-14
25巻
1号
開始ページ 99
終了ページ 109
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307452
JaLCDOI 10.18926/15442
フルテキストURL Mem_Fac_Eng_OU_28_1_87.pdf
著者 Motojima Isao| 河野 伊一郎| 西垣 誠|
抄録 In recent years, construction or planning of large-scale underground structures, such as underground power plants, underground oil storage plants and nuclear power plants have been coming into consideration in Japan. To construct such as large-scale underground structures, one of the most important problems is to make clear beforehand the behavior of groundwater around these structures and the other is to carry out proper countermeasure of groundwater, so that these structures can be constructed safely and maintained stability over a long time period. This report describes the results of theoretical studies on the drain systems and at the same time, discusses the drain systems around the underground cavern for the practical underground power stations.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1993-11-30
28巻
1号
開始ページ 87
終了ページ 128
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307220
JaLCDOI 10.18926/fest/11499
フルテキストURL 010_067_074.pdf
著者 Dewan Ashraf M.| Alam Md. Mahabubul| 西垣 誠|
抄録 The objective of this paper is to delineate flood prone areas and estimate damage in Greater Dhaka during the 1998 catastrophic flood using an integrated approach of GIS and remote sensing. Time series RADARSAT SAR data is acquired and used to demarcate flood boundaries for the 1998 flood event. This was accomplished by thresholding linear SAR imageries. Flood estimation demonstrated that flood areas steadily increased from early July 1998 and peaked on 25 August 1998 inundating 53% lands due to heavy monsoonal downpour and discharge from upstream points. Different thematic layers were combined with a derived flood map in order to assess flood damage for the same event. Flood damage analysis revealed that substantial damage has occurred in Greater Dhaka during the 1998 flood.
キーワード Synthetic Aperture Radar (SAR) flood delineation 1998 flood flood damage Greater Dhaka
出版物タイトル 岡山大学環境理工学部研究報告
発行日 2005-02-28
10巻
1号
開始ページ 67
終了ページ 74
ISSN 1341-9099
言語 英語
論文のバージョン publisher
NAID 120002313624
JaLCDOI 10.18926/15749
フルテキストURL Mem_Sch_Eng_OU_14_2_73.pdf
著者 Kono Iichiro| Nishigaki Makoto|
抄録 This paper deals with the experimental study of hydraulic properties of unsaturated soil. In treating unsaturated zone, a great deal more data are required than are required for the saturated zone, but these properties of soils must be known to apply the finite element approach to actual groundwater flow problems. The purposes of this paper are to propose a rational basis of getting experimental relationships between prossure head() and hydraulic conductivity(K) and between pressure head() and volumetric moisture content(θ) with "the instantaneous profile method" in a laboratory. An apparatus was constructed and test procedures were developed to measure pressure head and volumetric moisture content by using pressure transducers and low-energy gamma ray attenuation. The technique of a low-energy gamma radiation apparatus does provide a means for accurate measurement of water content without disturbing the system into which water is moving. Furthermore rapid measurement of water content becomes possible at any position in a soil so that water content changes with time may easily be followed. The tensiometer~transducer system provides a most valuable means of measuring pressure head with rapid response and with provision of a complete record of the pressure head changes with time.
出版物タイトル Memoirs of the School of Engineering, Okayama University
発行日 1980-03-01
14巻
2号
開始ページ 73
終了ページ 110
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307379
JaLCDOI 10.18926/fest/11433
タイトル(別表記) Measuring Method of Water Content for High compacted Bentonite Block by using Frequency Domain Reflectometry
フルテキストURL 011_057_064.pdf
著者 西垣 誠| 小松 満| 千々松 正和|
抄録 In the high-level radioactive waste disposal project, in order to know the infiltration behavior, it have to be examined that the bentonite buffer material is used as a barrier, and the measuring device of moisture with the high accuracy is required. In this study it is discussed the usefulness for Frequency Domain Refrectometry (FDR) method through the measuring dielectric constant and making the calibration curve for the several kinds of bentonite material block (pure and silica sand mixing).
キーワード Measuring syatem Bentonite Volumetric mousture content Frequency domain reflectometry
出版物タイトル 岡山大学環境理工学部研究報告
発行日 2006-03-15
11巻
1号
開始ページ 57
終了ページ 64
ISSN 1341-9099
言語 日本語
論文のバージョン publisher
NAID 120002313913
JaLCDOI 10.18926/15813
フルテキストURL Mem_Sch_Eng_OU_16_2_89.pdf
著者 Kohno Iichiro| Nishigaki Makoto|
抄録 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.
出版物タイトル Memoirs of the School of Engineering, Okayama University
発行日 1982-03-29
16巻
2号
開始ページ 89
終了ページ 99
ISSN 0475-0071
言語 英語
論文のバージョン publisher
NAID 120002307453