JaLCDOI 10.18926/ESR/47747
Title Alternative Newly proposed landform division in the Kibi Plateau area: Application for a hazard map of landslides
FullText URL esr_018_1_005_010.pdf
Author Suzuki, Shigeyuki| Omizo, Yuna| Hirata, Minoru| Nishigaki, Makoto|
Abstract The Kibi Plateau is characterized by horizontal skylines and they are considered to be an uplifted peneplain. Landform of the plateaus in central part of Okayama Prefecture is divided into "Kibi plateau landform" and "Recent dissecting landform". The Kibi plateau landform is composed of low relief surface and relict mountain. The altitude of the low relief surface varies from 300 to 450m in Kayo area, and 200 to 350m in Kanayama area. The Recent dissecting landform is characterized by escarpment and cuts the Kibi plateau landform. Knick-point is formed at the boundary between two landforms and steep slope is distributed just below the knick-point. The steep slope of the recent dissecting landform is unstable and a potential of landslide is high.
Keywords Kibi Plateau landslide knick-point Okayama Prefecture
Publication Title Okayama University Earth Science Report
Published Date 2011-12-26
Volume volume18
Issue issue1
Start Page 5
End Page 10
ISSN 1340-7414
language 日本語
Copyright Holders © 2011 by Okayama University Earth Science Reports Editorial Committee All Rights Reserved
File Version publisher
NAID 120003796475
Author Nishigaki, Makoto| Komatsu, Mitsuru| Kim, Man-il|
Published Date 2003-08
Publication Title 環境制御
Volume volume25
Content Type Departmental Bulletin Paper
JaLCDOI 10.18926/15835
FullText URL Mem_Sch_Eng_OU_21_1_71.pdf
Author Takeshita Yuji| Nishigaki Makoto| Kohno Iichiro|
Abstract 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.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1986-11-15
Volume volume21
Issue issue1
Start Page 71
End Page 79
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307954
JaLCDOI 10.18926/15813
FullText URL Mem_Sch_Eng_OU_16_2_89.pdf
Author Kohno Iichiro| Nishigaki Makoto|
Abstract 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.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1982-03-29
Volume volume16
Issue issue2
Start Page 89
End Page 99
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307453
JaLCDOI 10.18926/15795
FullText URL Mem_Sch_Eng_OU_16_1_65.pdf
Author Kohno Iichiro| Nishigaki Makoto|
Abstract 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.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1982-03-01
Volume volume16
Issue issue1
Start Page 65
End Page 89
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307205
JaLCDOI 10.18926/15749
FullText URL Mem_Sch_Eng_OU_14_2_73.pdf
Author Kono Iichiro| Nishigaki Makoto|
Abstract 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.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1980-03-01
Volume volume14
Issue issue2
Start Page 73
End Page 110
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307379
JaLCDOI 10.18926/15748
FullText URL Mem_Sch_Eng_OU_14_2_53.pdf
Author Nishigaki Makoto| Kono Iichiro|
Abstract 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.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1980-03-01
Volume volume14
Issue issue2
Start Page 53
End Page 72
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307170
JaLCDOI 10.18926/15744
FullText URL Mem_Sch_Eng_OU_14_1_95.pdf
Author Nishigaki Makoto| Kono Iichiro|
Abstract In order to apply the numerical method to practical groundwater flow problem in the field, the hydraulic properties must be estimated. In this paper, new methods of analyzing drawdown tests were developed and illustrated with some examples to determine hydraulic properties of aquifer. Drawdown tests sometimes have to be performed near the boundary of the aquifer or in the much groundwater supplied aquifer. In such instances, the assumption that the aquifer is of infinite areal extent is no longer valid. Therefore the analytical solutions of unsteady flow due to drawdown test are derived in the conception of "Island Model" that the shape of groundwater level is fixed by the circular water supply which is equilibrium with the pumping rate. By using these solutions, new methods of analyzing drawdown tests which are performed in a confined aquifer and an unconfined aquifer were given respectively and the effect of influence region was evaluated. The example analysis to determine permeability and storage coefficient were shown. As the results,the propriety of the solutions is verified comparing the analytical results with the drawdown test data taken from a real aquifer project.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1979-12-01
Volume volume14
Issue issue1
Start Page 95
End Page 126
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307822
JaLCDOI 10.18926/15742
FullText URL Mem_Sch_Eng_OU_14_1_61.pdf
Author Kono Iichiro| Nishigaki Makoto|
Abstract 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.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1979-12-01
Volume volume14
Issue issue1
Start Page 61
End Page 94
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307580
JaLCDOI 10.18926/15731
FullText URL Mem_Sch_Eng_OU_12_97.pdf
Author Kono Iichiro| Nishigaki Makoto|
Abstract 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.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1978-02-25
Volume volume12
Start Page 97
End Page 128
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307830
JaLCDOI 10.18926/15498
FullText URL Mem_Fac_Eng_OU_25_1_99.pdf
Author Nishigaki, Makoto| Takeshita, Yuji| Kono, Iichiro|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-12-14
Volume volume25
Issue issue1
Start Page 99
End Page 109
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307452
JaLCDOI 10.18926/15492
FullText URL Mem_Fac_Eng_OU_25_1_59.pdf
Author Kohno, Iichiro| Nishigaki, Makoto| Okada Junji|
Abstract In this paper, we propose a method to determine the coefficients of permeability of the unconfined aquifer consisted of two different permeability layers. With mixing the conventional pumping test and falling head permeability test, the coefficients of permeabilitiy k(1) and k(2) were obtained. The validity of the proposed method is investigated by using the numerical simulation. As the results, it becomes apparent that the proposed method is applicable to real hydarulic problems.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-12-14
Volume volume25
Issue issue1
Start Page 59
End Page 69
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307472
JaLCDOI 10.18926/15483
FullText URL Mem_Fac_Eng_OU_24_1_107.pdf
Author Kohno, Iichiro| Nishigaki, Makoto| Takeshita, Yuji|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1989-11-29
Volume volume24
Issue issue1
Start Page 107
End Page 114
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307749
JaLCDOI 10.18926/15463
FullText URL Mem_Fac_Eng_OU_28_2_59.pdf
Author Nishigaki, Makoto| Sun Yao| Kohno, Iichiro|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1994-03-15
Volume volume28
Issue issue2
Start Page 59
End Page 75
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307850
JaLCDOI 10.18926/15451
FullText URL Mem_Fac_Eng_OU_22_45.pdf
Author Kohno, Iichiro| Nishigaki, Makoto| Takeshita, Yuji|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1988-03-31
Volume volume22
Start Page 45
End Page 62
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307536
JaLCDOI 10.18926/15442
FullText URL Mem_Fac_Eng_OU_28_1_87.pdf
Author Motojima Isao| Kono, Iichiro| Nishigaki, Makoto|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1993-11-30
Volume volume28
Issue issue1
Start Page 87
End Page 128
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307220
JaLCDOI 10.18926/15440
FullText URL Mem_Fac_Eng_OU_28_1_71.pdf
Author Nishigaki, Makoto| Sudinda Teddy| Hishiya Tomoyuki| Kohno, Iichiro|
Abstract 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].
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1993-11-30
Volume volume28
Issue issue1
Start Page 71
End Page 85
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307975
JaLCDOI 10.18926/15398
FullText URL Mem_Fac_Eng_OU_27_1_93.pdf
Author Nishigaki, Makoto| Sudinda Teddy| Hishiya Tomoyuki| Kohno, Ichiro|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1992-11-25
Volume volume27
Issue issue1
Start Page 93
End Page 105
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307768
JaLCDOI 10.18926/fest/15045
FullText URL 014_023_028.pdf
Author Chegbeleh Larry Pax| Nishigaki, Makoto| Akudago John Apambilla| Alim Md. Abdul| Komatsu, Mitsuru|
Abstract During underground space development, groundwater seepage mostly occurs which may seriously affect the stability of deep excavations as well as retard progress of construction. For smooth progress of work, effective construction and operation of a disposal facility for high level radioactive waste (HLW), it is important to control seepage into excavations by sealing off fractures or fissures and excavation disturbed zones (EDZ) to control groundwater inflow during the construction phase of such a facility. In this study, a series of experiments were conducted on ethanol/bentonite slurries in the laboratory with the aim of determining the effect of a hydrophilic solvent such as ethanol on the hydraulic and injection characteristic of bentonite slurry for the sealing of fissures to control ground water seepage during the construction phase of a repository. Preliminary results revealed ethanol/bentonite slurry as an effective grouting material capable of penetrating micro fractures (100μm or less) and with the permeability of the grouted medium being as low as 10E-7cm/s. The results also show that the effectiveness and efficiency of grouting is dependent on the type of injection and fissure size. Dynamic injection was observed to be efficient as it was able to inject high dense slurry.
Keywords Dynamic injection permeability swelling bentonite clay
Publication Title 岡山大学環境理工学部研究報告
Published Date 2009-03-16
Volume volume14
Issue issue1
Start Page 23
End Page 28
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002307422
JaLCDOI 10.18926/fest/15044
FullText URL 014_017_022.pdf
Author Akudago John Apambilla| Nishigaki, Makoto| Chegbeleh Larry Pax| Komatsu, Mitsuru| Alim Md. Abdul|
Abstract 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.
Keywords soil-groundwater salinity capillary cut filter media design
Publication Title 岡山大学環境理工学部研究報告
Published Date 2009-03-16
Volume volume14
Issue issue1
Start Page 17
End Page 22
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002308001