Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Chapter of International Geosynthetics Society  

DOI： 10.5030/jcigsjournal.34.197

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J-GLOBAL

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Authorship：Lead author   Language：English  

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Language：English   Publisher：公益社団法人 農業農村工学会  

This paper presents a model using the Dupuit approximation applicable to the case in which a small homogeneous earth dam constructed on inclined foundation in order to estimate the phreatic surface location and the seepage discharge through the dam. Analytical results obtained from the model are validated by comparison with the results obtained from a BEM model of the Laplacian field. Main results are as follows: i) The phreatic surface location of the analytical result of the model tends to be higher than that computed by the BEM, ii) The height of the seepage-out point obtained from the analytical result is almost identical with that by the BEM, and iii) The seepage discharge obtained from the analytical result is larger than that by the BEM; their ratio is between 1.113 and 1.243. From all results of the test cases, it is shown that these analytical results are useful for analyzing seepage through a homogeneous earth dam on inclined foundation.

DOI： 10.11408/jsidre.80.261

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Language：English   Publisher：Japan Society on Water Environment  

Suspended sediment load in relatively smaller rivers draining agricultural areas was monitored and the suspended sediment rating curve was established using two regression analysis approaches—applying data stratification to ameliorate the prediction model equations. The sediment load data were observed for forty-five months in three rivers in an agricultural area in southern Ehime Prefecture, Japan. The data were analyzed using the power function and detransformed logarithmic function regression methods, while testing and elucidating the appropriateness and efficiency of these regression methods. Results showed that data stratification significantly improved the discharge-sediment load correlation and reduced curve-fitting errors, thereby, improving the efficiency of the derived model equation. Moreover, data stratification was found necessary in the analysis to account for nil sediment concentration observed during low flow periods. Between the two regression analysis methods, power function regression appears to have better predictive capability and, thus, more appropriate to smaller rivers. Specifically, as compared to the detransformed logarithmic function regression, power function yields models with significantly higher correlation and efficiency coefficients, as well as predicted sediment load closer to the observed sediment load.

DOI： 10.2965/jwet.2012.387

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Language：English   Publisher：日本雨水資源化システム学会  

This paper investigates applicability of the method determining blanket design length based on the analytical solution proposed by Yoshitake et al. (2011) to smaller embankment dams, and demonstrates its validity to the application of half-size of the dams employed in the previous study through the comparison with results computed by BEM. Then, the reason why the resultant design blanket length of smaller dams is always larger than that of larger ones is investigated by introducing the idea of effective seepage path length. This investigation reveals that the effective seepage path lengths of the half-sized dams are almost the same as those of the original dams, keeping the high accuracy of analysis compared to the BEM solution.

DOI： 10.7132/jrcsa.KJ00008229264

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Language：English   Publisher：日本雨水資源化システム学会  

Water quality characterization is important, and often, the first step in watershed water quality management. The characterization activity centers on the quantification of water quality parameters relevant to the monitoring objective and the analyses of the impact of the parameters on the state of water body. This study characterizes the general water quality of a network of agricultural rivers in Southern Ehime, Japan and conducted Factor Analysis (FA) and Cluster Analysis (CA) to determine the causal factors and spatial variation of pollution. The Water Quality Index (WQI), based on nine water quality parameters, was computed and optimized-determining the parameters that could best predict the overall water quality. Results show that the river sampling sites have good overall water quality and that physico-chemical parameters pH, DO, and BOD_5 best correlated and predicted WQI. Based on the FA, the primary factors that influence pollution in the sites are the solids or sediment transport (turbidity and sediment), inorganic pollution (NO_3-N, PO_4-P) and trophicity (total N, total P, fecal bacteria). CA, on the other hand, somehow provides information on the effect of the tributaries to the receiving rivers.

DOI： 10.7132/jrcsa.KJ00008229263

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Language：Japanese   Publisher：公益社団法人 土木学会  

Annual SS (Suspended Solids) load from the Hiromi river to the Shimanto river was estimated based on the 33-months continuous daily observation data. The water quality of the Shimanto river, which is often called "the last clear stream of Japan", is observably deteriorated especially during rice transplanting period. Suspended load prediction models were established and the effect,of rice transplanting activities to the rivers' suspended load was also estimated. Results showed that the amount of annual SS load to the Shimanto river from the Hiromi river was 9.8x10<sup>6</sup> kg and if drainage from paddy fields during rice transplanting is completely stopped, the amount could be reduced by 8.0-12x10<sup>4</sup> kg SS.

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Language：English   Publisher：農業農村工学会  

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Language：English   Publisher：農業農村工学会  

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Language：English   Publisher：農業農村工学会  

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Language：Japanese   Publisher：日本雨水資源化システム学会  

When partially saturated soils swell and their water content increases, its soil structures supported by negative pressure are destroyed causing volume compression (collapse) and/or volume expansion (swelling). On the other hand, though compaction controls of embankment are managed by D-value (=ρ_d/ρ_<dmax>), the relation among volume change due to submergence, D-value, and consolidation pressure for the dynamically compacted soil is not examined sufficiently. In this study, the volume change was tested with Fujinomori clay, decomposed granite soil and Daisen loam by using oedometers; and the effect of D-value, consolidation pressure and water content on the volume change was verified.

DOI： 10.7132/jrcsa.KJ00005702904

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Language：Japanese   Publisher：農業農村工学会  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：A A BALKEMA  

Web of Science

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Some of dense costal forests in tropical areas protected several villages from tsunami hazard in 2004 Indian Ocean Tsunami. Several physical and numerical researches to simulate the reduction rate of tsunami force by the forests have been carried out. A few surveys were, however, done to evaluate the prototype effects of the forest in the field devastated in tsunamis but any clear quantitative evidence for the effects was not revealed. A field survey to measure the dense of coastal forest and to validate the simulation results for the tsunami force reduction by coastal vegetation was carried out after the 2008 Solomon Island Earthquake Tsunami. The results demonstrated the validity of the simple calculation method applying the experimentally derived drag force coefficient in dense vertical columns resembling trees.

DOI： 10.2208/proce1989.55.1411

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Language：English   Publisher：ELSEVIER SCI LTD  

The subgrade reaction coefficient of a foundation soil in an open pier has been identified using an extended Kalman filter (EKF) based on measurements taken during in situ horizontal loading tests on a pile. For the in situ tests, the surface clay layer was removed, and the diluvial clay layer was replaced by a rubble mound to reduce the length of the pile above the surface of the foundation deposit. The tests were carried out for both the existing diluvial clay deposit and the replacement rubble mound for purposes of comparing the identified subgrade reaction coefficients in Euler-Bernoulli's beam equation with nonlinear springs. The measured deflection and the bending moment determined in the tests were used as input data for the inverse analysis. Analysis revealed that the identified subgrade reaction coefficient of the rubble mound is less than that of the diluvial clay under the same level of loading. The numerical results will provide useful information for the future design of open piers and their foundations. (C) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.compgeo.2007.11.002

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Publisher：公益社団法人 土木学会  

Some of dense costal forests in tropical areas protected several villages from tsunami hazard in 2004 Indian Ocean Tsunami. Several physical and numerical researches to simulate the reduction rate of tsunami force by the forests have been carried out. A few surveys were, however, done to evaluate the prototype effects of the forest in the field devastated in tsunamis but any clear quantitative evidence for the effects was not revealed. A field survey to measure the dense of coastal forest and to validate the simulation results for the tsunami force reduction by coastal vegetation was carried out after the 2008 Solomon Island Earthquake Tsunami. The results demonstrated the validity of the simple calculation method applying the experimentally derived drag force coefficient in dense vertical columns resembling trees.

DOI： 10.2208/proce1989.55.1411

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Publisher：公益社団法人 農業農村工学会  

One of the representative algorithms for learning of an artificial neural networks (ANN) is the back propagation method. But, it is sometimes difficult to converge and learn efficiently, because it minimizes the error function of the outputs for each learning data set in order and not simultaneously. In order to minimize the error functions for all learning data sets simultaneously, a new learning algorithm is proposed using the extended Bayesian method. However, a dificult but important problem in this method is to determine optimally the number of hidden layer units <I>L<SUB>m</SUB></I> for ANN and the parameter λ<SUP>2</SUP> for the extended Bayesian method. Thus, the determination method of optimal λ<SUP>2</SUP> and <I>L<SUB>m</SUB></I> by Akaike Bayesian information criteria is proposed. As a result of having applied it to consolidation and seismic problems, it is comparatively clear that the proposed method has faster convergence and higher learning capability.

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Language：Japanese   Publisher：農業農村工学会  

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DOI： 10.11408/jsidre2007.2007.727

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Language：Japanese   Publisher：海岸林学会  

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Language：English  

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Publisher：公益社団法人 農業農村工学会  

Many irrigation tanks need their rehabilitation urgently, because they are centuries-old. This paper is associated with excess leakage of impounded water through an earthen embankment. An attempt to identify leaky embankment transactions using the result of field investigation, to decide the rehabilitation method and to estimate the permeability of the improved embankment is made for an overage tank in Ehime prefecture, Japan.<BR>There seems to be a highly permeable layer between F.W.L. and W.L.-5.0m in the embankment judging from the <I>in-situ</I> up-to-date data and the hydro-geological data. And, the identification enabled the small scale improvement work, namely, the embankment of 10.0m depth from the crown was excavated and replaced by the impermeable soil. Further, the electrical resistivity surveying was carried out and the validity of the rehabilitation work was demonstrated by comparing between the results of the improved zone and the original zone.

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Language：Japanese   Publisher：海岸林学会  

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Language：Japanese   Publisher：農業土木学会  

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DOI： 10.11408/jsidre1965.2006.323

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Language：Japanese   Publisher：海岸林学会  

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Publisher：社団法人 農業農村工学会  

The failure of embankment such as a levee and an earth dam may be caused by overflow, seepage (water leakage), scour or crack. The common cause of failure is piping (seepage path) through embankments. This paper shows a simple method of a numerical simulation for piping failure in order to investigate the process, that is, the piping phenomenon is assumed as the optimal permeability field under a certain condition and the seepage property of the field changes to adjust to neighboring environmental changes using cell automaton. The simple rule that a permeability coefficient changes depending on seepage velocity generated in the seepage field is applied to the cell automaton and the piping phenomenon is simulated in a cross section of the embankment with the finite element saturated seepage analysis.

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Language：Japanese   Publisher：農業土木学会  

DOI： 10.11408/jsidre1965.2005.17

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Language：Japanese  

DOI： 10.11345/japannctam.54.0.24.0

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

Water is most dense at 4℃ and becomes less dense at both higher and lower temperatures. Because of the density-temperature relationship, many reservoirs in temperate climates tend to stratify. The water warmed by the sun will remain at the surface (epilimnion), while the dense and cold water sinks to the bottom (hypolimnion). The layer separating the two layers is the thermocline. These layers do not mix, and the hypolimnion is cut off from atmospheric oxygen and suffers from environmental degradation such as eutrophication. Organic sludge is removed by dredging and self-purification of reservoir is produced by supplying oxygen to a hypolimnion by aeration to improve this environmental degradation. In this paper, we suggest new water purification system without aeration or dredging. The system promotes photosynthesis of phytoplankton at a disphotic and hypoxic bottom layer by irradiating artificial light directly. Our concern is to inspect that this system can supply oxygen with phytoplankton living in a hypoxic hypolimnion.

DOI： 10.7132/jrcsa.KJ00004364681

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Publisher：社団法人 農業農村工学会  

Over the past few decades, a considerable number of studies that generate an optimal structure under a loading and boundary condition have been made and Evolutionary Structural Optimization (ESO) method is one of the most effective techniques. The mathematical model is based on the remodeling (self-organization) of biological systems such as a bone and a tree. There have been some weak points where a reasonable solution cannot necessarily be concluded in it.<BR>A new method (R-ESO method) that consists of three optimization processes, that is, the removal process, addition process and growth process is proposed and some simple numerical examples show the effectiveness of the method. Also, it is applied to optimizing the structures of concrete dams, and the obtained final solutions are similar to the shape of an existing concrete dam with satisfying the stable condition.

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Publisher：日本学術会議 「機械工学委員会・土木工学・建築学委員会合同IUTAM分科会」  

The coefficient of the subgrade reaction of a foundation ground is identified by Extended Kalman filtering based on measurements of horizontal loading tests on piles in a laboratory. A pile is modeled as a beam on nonlinear elastic foundation and its behavior is solved by FEM. The laboratory experiments are carried out for model pile embedded in homogeneous sandy soil. The items of observation data for Kalman filtering are deformation and bending moment of the pile. The moment is obtained by multiplying bending strain and conversion factor EZ and integrated to obtain the deformation. The numerical results will provide objective and useful information for the design of the pile.

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Language：English   Publisher：日本雨水資源化システム学会  

Water is most dense at 4℃ and becomes less dense at both higher and lower temperatures. Because of the density-temperature relationship, many reservoirs in temperate climates tend to stratify. The water warmed by the sun will remain at the surface (epilimnion), while the dense and cold water sinks to the bottom (hypolimnion). The layer separating the two layers is the thermocline. These layers do not mix, and the hypolimnion is cut off from atmospheric oxygen and suffers from environmental degradation such as eutrophication. Organic sludge is removed by dredging and self-purification of reservoir is produced by supplying oxygen to a hypolimnion by aeration to improve this environmental degradation. In this paper, we suggest new water purification system without aeration or dredging. The system promotes photosynthesis of phytoplankton at a disphotic and hypoxic bottom layer by irradiating artificial light directly. Our concern is to inspect that this system can supply oxygen with phytoplankton living in a hypoxic hypolimnion.

DOI： 10.7132/jrcsa.KJ00004364681

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

Water is most dense at 4℃ and becomes less dense at both higher and lower temperatures. Because of the density-temperature relationship, many reservoirs in temperate climates tend to stratify. The water warmed by the sun will remain at the surface (epilimnion), while the dense and cold water sinks to the bottom (hypolimnion). The layer separating the two layers is the thermocline. These layers do not mix, and the hypolimnion is cut off from atmospheric oxygen and suffers from environmental degradation such as eutrophication. Organic sludge is removed by dredging and self-purification of reservoir is produced by supplying oxygen to a hypolimnion by aeration to improve this environmental degradation. In this paper, we suggest new water purification system without aeration or dredging. The system promotes photosynthesis of phytoplankton at a disphotic and hypoxic bottom layer by irradiating artificial light directly. Our concern is to inspect that this system can supply oxygen with phytoplankton living in a hypoxic hypolimnion.

DOI： 10.7132/jrcsa.KJ00004364681

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Language：Japanese   Publisher：日本雨水資源化システム学会  

DOI： 10.7132/jrcsa.KJ00004364659

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Language：English   Publisher：MILLPRESS SCIENCE PUBLISHERS  

There are four large faults in Shikoku Island in the western Japan, Median Tectonic Line, Mikabu fault, Butsuzou fault and Aki-Sukumo fault. Near the Mikabu fault many landslides have occurred and some landslides continue to slide. A landslide at Yanadani in Shikoku Island slid down about 4 cm after Geiyo earthquake which occurred in March 2001. The resistivity image of this landslide obtained with electrical exploration was used together with geological information and seismic refraction data for the landslide analysis by FEM (Finite Element Method). The resistivity image showed a fault, and the landslide was affected by the fault.

Web of Science

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DOI： 10.11408/jsidre1965.2003.601

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Language：Japanese   Publisher：農業土木学会  

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Language：Japanese   Publisher：社団法人 農業農村工学会  

DOI： 10.11408/jjsidre1965.71.8_767

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DOI： 10.11408/jsidre1965.2003.303

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Language：Japanese   Publisher：日本雨水資源化システム学会  

A finite element modeling for three-dimensional analysis of saturated-unsaturated steady state seepage flow in hydrogeological complexity is attempted in order to investigate the effect of grouting works on seeping water losses from the damsite and reservoir of the Nakadake Dam, Japan. In the left hillside of the reservoir, the area where groundwater level is lower than the full water level of the dam reservoir stretches far from the damsite and therefore how to design the grouting works becomes a crucial problem. To clear up the effect of the rainfall recharge on seepage flow, two series of analysis are carried out: Series A and B with and without rainfall recharge, respectively. For the respective series, total flow rates and seepage losses are estimated in relation to the length of the grouting works. To investigate in more detail flow rates across the grouting limb, the partial flow rates across seven fragmented limbs are compared. As a result, the total flow rate for Series A is larger than that for Series B, but there is a slight difference in flow rate characteristics between both series. When the limb length is 1.20 and 1.88 times as large as the magnitude of full reservoir water depth, the total flow rate becomes about 43% and 55% of that without grouting works, respectively. In the latter case, however, seepage loss is not so effectively reduced although the limb is longer. This is because the flow taking a detour without going through the grouted limb significantly contributes to the aggregate seepage loss.

DOI： 10.7132/jrcsa.KJ00000795204

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Language：Japanese   Publisher：社団法人 農業農村工学会  

This paper clarifies the properties of ground motions observed by K-net and KiK-net of National Research Institute for Earth Science and Disaster Prevention during the Geiyo earthquake in 2001, and non-linear seismic response analyses with Ramberg-Osgood model are conducted for a damaged dam. To investigate the relationship between crack generation and properties of the dam, especially to verify the effect of soil stabilized by lime and water level of reservoir, 4 cases of analyses are carried out. As a result, soil stabilized by lime is shown to have a significant effect on the crack generation at the top of dam and these are independent of water level. Sliding failure during the earthquake was not occurred and also the slope stability can be confirmed by the evaluation with local safety factor derived from the analytical results.

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Language：English   Publisher：A A BALKEMA PUBLISHERS  

The coefficient of the subgrade reaction of a foundation ground at an open pier is identified by Kalman filtering based on measurements of in-situ horizontal loading experiments on piles. For the in-situ tests, the surface clay layer was removed and the diluvial clay layer was replaced by a rubble mound to shorten the length of the pile above the surface of the foundation deposit. In-situ tests were carried out for both the existing clay deposit and the replaced mound for comparison with the identified coefficient of subgrade reaction in Chang's model. The measured displacement and the bending moment are adopted as input data for the inverse analysis. It is revealed from the inverse analysis that the identified coefficient of the subgrade reaction of the rubble mound is less than that of the diluvial clay under the same level of loading. The numerical results will provide useful information for the design of open piers and their foundations.

Web of Science

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Publisher：社団法人 農業農村工学会  

Rim grouting works are performed in order to reduce seepage loss from a reservoir. They don't work so efficiently when their length becomes longer than a certain length. To estimate seepage loss in relation to the length of rim grouting works, a finite element analysis for three dimensional saturated-unsaturated steady state seepage flow is attempted. Seepage domain used here is a rectangular parallelepiped. Two series of analysis are carried out. Recharge due to precipitation is taken into account in one series (Series A) and not in another (Series B). As a result, the total flow rate in Series B is larger than that in Series A, but there is a slight difference of the flow rate characteristics between both series. Then, the flow rate characteristics and the effects of rim grouting works on seepage loss reduction in only Series B are investigated in more detail. As a result of our analysis, the remarkable effect of rim grouting works on seepage loss reduction lies up to the length of rim grouting works which is shorter than about 2.5 times of the depth of full reservoir water and this is because the seepage flow near the abutment is dominant. The detouring flow into no grouting works zone has a significant influence on the flow rate.

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

Soil property varies randomly in a field and there is some correlation between its values at any two points. Especially, in an artificial soil structure like an embankment, it has some anisotropic spatial correlation due to constructive features. In our earlier work, the effect of the standard deviation and the correlation distance of soil permeability on total flow rate in a random field with isotropic spatial correlation has been clarified and spatial spanning of lower or higher permeability that forms "impervious wall" or "flow path" has been reproduced by Percolation theory. This paper attempts to evaluate objectively fracture characteristics of random field with anisotropic spatial correlation by using fractal dimensions. Spatially correlated random fields with anisotropic spatial correlation distance are generated, and fractal dimensions are examined for each of these random fields. As a result, the fractal dimensions are shown to have some close relation to the anisotropic spatial correlation in random fields.

DOI： 10.7132/jrcsa.KJ00000795200

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

Soil property varies randomly in a field and there is some correlation between its values at any two points. Especially, in an artificial soil structure like an embankment, it has some anisotropic spatial correlation due to constructive features. In our earlier work, the effect of the standard deviation and the correlation distance of soil permeability on total flow rate in a random field with isotropic spatial correlation has been clarified and spatial spanning of lower or higher permeability that forms "impervious wall" or "flow path" has been reproduced by Percolation theory. This paper attempts to evaluate objectively fracture characteristics of random field with anisotropic spatial correlation by using fractal dimensions. Spatially correlated random fields with anisotropic spatial correlation distance are generated, and fractal dimensions are examined for each of these random fields. As a result, the fractal dimensions are shown to have some close relation to the anisotropic spatial correlation in random fields.

DOI： 10.7132/jrcsa.KJ00000795200

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DOI： 10.11408/jsidre1965.2002.683

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Language：Japanese   Publisher：農業土木学会  

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DOI： 10.11408/jsidre1965.2002.697

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

It is of great significance to employ a statistical approach to the seepage problem with spatially high variability of soil properties. In our earlier work, it has been demonstrated that with the increasing standard deviation of permeability coefficient the mean seepage flow rate decreases and its covariance increases, and this is a result of spatial spanning of lower or higher permeability. Using the percolation theory, this paper attempts to reproduce such spatial spanning that forms "impervious wall" or "flow path". Spatially correlated random permeability fields are generated, and the finite element seepage analysis is carried out for each of these fields to examine percolation properties. As a result, it is shown that the indexes of percolation (i. e., threshold and threshold probability), defined in the percolation theory, could characterize the total flow rate in random permeability field with the same means, standard deviation and correlation distance.

DOI： 10.7132/jrcsa.KJ00003257908

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Publisher：社団法人 農業農村工学会  

This paper shows a simple system for seismic risk evaluation of small earth dams. The data of site investigation for damaged dams and “Database System on Small Earth Dam for Preventing Disaster” is used to this system and the neural networks are applied to the proposed methodology. Factors of earthquake damage are assumed to be 16 characteristics of a dam and an earthquake;(1) dam type, (2) dam height, (3) crest length, (4) crest width, (5) upstream slope, (6) downstream slope, (7) soil classification of embankment, (8) era of dam construction, (9) rehabilitated history, (10) damaged history, (11) topography, (12) surface geology of dam site, (13) soil property of dam site, (14) geological age, (15) distance to epicenter and (16) acceleration at dam site. The case study through the Geiyo Earthquake in 2001 in which the objective area is Ehime Prefecture is conducted and availability of the system is evaluated.

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Language：Japanese   Publisher：社団法人 農業農村工学会  

Coefficient of subgrade reaction of the rubble mound in the foundation of the open pier or the mooring post is identified by the Kalman filtering in conjunction with the transfer matrix method based on the measurement of in-situ experiments of piles. The existing surface clay layer is removed and the dilluvial clay layer is replaced by the rubble mound to shorten the length of the pile above the surface of the foundation deposit. In-situ experiments were carried out for both the existing clayey layer and the rubble mound. Measured data for the inclinometer is differentiated to obtain the moment and integrated to obtain the displacement along the pile, and they are used as the input for inverse analysis. Identified coefficient of the rubble mound using these measurements is less than that of the dilluvial clay under the same level of the loading. Numerical results provide useful information for the design of the open pier and its foundation.

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

It is of great significance to employ a statistical approach to the seepage problem with spatially high variability of soil properties. In our earlier work, it has been demonstrated that with the increasing standard deviation of permeability coefficient the mean seepage flow rate decreases and its covariance increases, and this is a result of spatial spanning of lower or higher permeability. Using the percolation theory, this paper attempts to reproduce such spatial spanning that forms "impervious wall" or "flow path". Spatially correlated random permeability fields are generated, and the finite element seepage analysis is carried out for each of these fields to examine percolation properties. As a result, it is shown that the indexes of percolation (i. e., threshold and threshold probability), defined in the percolation theory, could characterize the total flow rate in random permeability field with the same means, standard deviation and correlation distance.

DOI： 10.7132/jrcsa.KJ00003257908

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DOI： 10.11408/jsidre1965.2001.687

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Language：Japanese   Publisher：農業土木学会  

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Language：English   Publisher：農業土木学会  

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Publisher：社団法人 農業農村工学会  

Three dimensional finite element analysis of saturated-unsaturated steady state seepage flow is applied to estimating limb grouting effects on detouring seepage flow under hydrogeological complex condition. At the damsite of interest, the observed ground water table is in the low level and the geological structure is very complicated. Therefore, it is very difficult to decide the range of limb grouting work. Major efforts in modeling are made on calibrating the model by trial and error. For this, all available information obtained by prior and posterior field surveys is employed in better identifying the spatial distribution of permeability. The results show that the model can be calibrated with practically acceptable biases from the observed reality. By use of the calibrated model, daily seepage losses can successfully be estimated in relation to the length of the grout line, and therefore the most reasonable length of the grout line can be determined. Thus the model-based seepage estimation technique presently described could be regarded as a guideline for using three dimensional finite element seepage analysis under hydrogeological complex condition at the damsite.

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

In many design practices for rehabilitation or construction of earthen embankments, a deterministic approach is employed for seepage flow analysis, assuming hydrogeological homogeneity of embankment soils. Since in fact soil permeability is heterogeneous, such a conventional approach may often mislead engineers into making an inadequate design with less structural safety and less economical efficiency. This paper intensively investigates reliability of seepage analysis based on a statistical approach that can consider spatial variations of soil permeability. First, random fields with mean, standard deviation and spatial correlation structure are generated, and then finite element seepage analysis in these random fields is performed. The statistical analyses are then implemented through the procedure of Monte Carlo simulation. The statistical solutions to a confined seepage flow problem are compared with the theoretical solution based on deterministic approach. As a result, the mean flow rate Q_m becomes far from the theoretical value Q_t as the global standard deviation σ_k and/or the correlation distance a increase. The spatial correlation structure, not to mention the mean and the standard deviation of permeability, is shown to have a significant effect on seepage flow rate.

DOI： 10.7132/jrcsa.KJ00003257892

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

In many design practices for rehabilitation or construction of earthen embankments, a deterministic approach is employed for seepage flow analysis, assuming hydrogeological homogeneity of embankment soils. Since in fact soil permeability is heterogeneous, such a conventional approach may often mislead engineers into making an inadequate design with less structural safety and less economical efficiency. This paper intensively investigates reliability of seepage analysis based on a statistical approach that can consider spatial variations of soil permeability. First, random fields with mean, standard deviation and spatial correlation structure are generated, and then finite element seepage analysis in these random fields is performed. The statistical analyses are then implemented through the procedure of Monte Carlo simulation. The statistical solutions to a confined seepage flow problem are compared with the theoretical solution based on deterministic approach. As a result, the mean flow rate Q_m becomes far from the theoretical value Q_t as the global standard deviation σ_k and/or the correlation distance a increase. The spatial correlation structure, not to mention the mean and the standard deviation of permeability, is shown to have a significant effect on seepage flow rate.

DOI： 10.7132/jrcsa.KJ00003257892

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Publisher：社団法人 農業農村工学会  

The 1997 Kagoshimaken-Hokuseibu Earthquake hit the reclamation land and dikes in Izumi City, and damage by liquefaction was inflicted on paddy fields and dikes. On the affected reclamation dikes, countermeasure construction against liquefaction was carried out based on the seismic design.<BR>In this paper, liquefaction behavior of the reinforced reclamation dike and the surrounding ground during the earthquake is simulated by the finite element method with nonlinear dynamic effective stress analysis. The development mechanism of excess pore water pressure is clarified from the viewpoint of stress history of the ground, and the effect of the countermeasure construction against liquefaction is verified. In the analysis of countermeasures for liquefaction, the development of the pore water pressure is suppressed, and the computed deformation values also decrease in comparison with the result of the analysis on the damage situation. Also, it is found that the stress path during earthquake depends largely on the initial stress condition, that is, the initial shear stress and the overburden pressure distribution, and the initial stress increase due to the countermeasures restrains the occurrence of liquefaction.

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DOI： 10.7132/jrcsa.KJ00003257892

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Language：English   Publisher：社団法人 農業農村工学会  

The 1997 Kagoshimaken-Hokuseibu Earthquake brought about damage to various structures, and agricultural facilities also suffered damage. Especially, damage by liquefaction was inflicted on the reclamation dikes in Izumi City. Sand boils at the bottom of water channels and in paddy fields, cracks and collapses in the pavement of the reclamation dikes, and deformation of revetments by liquefaction occurred at that time.<BR>In this paper, the behaviors of the reclamation dikes and the surrounding ground during the earthquake are simulated by numerical analysis and liquefaction behavior in the disaster is clarified. Simulation using nonlinear dynamic effective stress analysis is carried out in order to consider the effect of deterioration of shear stiffness by the excess pore water pressure developed during the earthquake. Results of the finite element analysis are basically consistent with the observed performance of the reclamation dikes and the surrounding ground, and it is possible to reproduce the ground motion, the distribution of the pore water pressure and the deformation.

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Language：Japanese   Publisher：社団法人 農業農村工学会  

The observational procedure is often used for difficult excavation works such as large-scale excavation, excavation with extensive depth, excavation in soft ground and excavation neighboring other structures to improve construction management. Features of the observational procedure are in respect of the optimum design change (the posteriori design) from measurement data under construction, when the uncertainty in the design before construction (the prior design) was positively recognized. However, it is difficult to judge whether it was “optimum design”, sincethe construction work is generally a single item production in the field. Therefore, there are not small cases in which the evaluation that it becomes the disturbance of the construction is received on the observational procedure. In this paper, the effectiveness in safety and economical efficiency of the observational procedure is objectively evaluated by the comparison between non-observation construction and observational procedure. The approach of expectation total cost used in the reliability design is used for the method of the evaluation of the effectiveness.

DOI： 10.11408/jsidre1965.2000.811

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Language：Japanese   Publisher：The Japanese Society of Irrigation, Drainage and Rural Engineering  

The observational procedure is often used for difficult excavation works such as large-scale excavation, excavation with extensive depth, excavation in soft ground and excavation neighboring other structures to improve construction management. Features of the observational procedure are in respect of the optimum design change (the posteriori design) from measurement data under construction, when the uncertainty in the design before construction (the prior design) was positively recognized. However, it is difficult to judge whether it was "optimum design", sincethe construction work is generally a single item production in the field. Therefore, there are not small cases in which the evaluation that it becomes the disturbance of the construction is received on the observational procedure. In this paper, the effectiveness in safety and economical efficiency of the observational procedure is objectively evaluated by the comparison between non-observation construction and observational procedure. The approach of expectation total cost used in the reliability design is used for the method of the evaluation of the effectiveness.

DOI： 10.11408/jsidre1965.2000.811

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Language：English   Publisher：Japan Rainwater Catchment Systems Association  

Small-scale irrigation tanks have been an important source of irrigation in Japan. These contribute nearly 10% of the total irrigated area, controlling the ravages of drought. Since many of the total 246,158 tanks are centuries-old, their rehabilitation and/or modernization are in emerging need. This paper is associated with one of the serious issues envisaged, i. e., excess leakage of impounded water through an earthen embankment. As a case study, an attempt is made to identify leaky embankment transections for an overage tank in Matsuyama, Ehime Prefecture, Japan, which is in real need of rehabilitation to prevent a calamity of the subsequent embankment-break. Using the up-to-date data (tank water level, water level and temperature in the boreholes installed, leaked water amount, etc.) obtained from long-term in-situ observations, their relational analyses are carried out to investigate the hydro-geological aspects of the embankment and find a transection of major leakage-path. The results demonstrate that the leaky transection with extremely high permeability (1.0 × 10^<-2> cm/s) exists closely to the right-bank of the tank, and the flow seeping along the toe of the embankment is indeed a result of leakage of the impounded water.

DOI： 10.7132/jrcsa.KJ00003257858

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DOI： 10.7132/jrcsa.KJ00003257858

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Language：Japanese  

DOI： 10.2208/jscej.1999.631_193

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J-GLOBAL

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Language：Japanese   Publisher：土木学会  

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Language：Japanese  

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J-GLOBAL

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Language：Japanese   Publisher：地盤工学会  

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Observational Procedure of the excavation work is mainly used for safe management. The prediction based on measurement data during construction is more reliable than the prediction at the design stage before construction. If the values are utilized more effectively, we will be able to execute the construction works rationally. So, Estimation of the design parameters and prediction in the behavior of the structure play the important roles in the observational procedure, and are demanded high reliability.&lt;br&gt;In this paper, the relationship between the error of measurement data and prediction results and the error in modeling of prediction are specified. And the reliability of the prediction are estimated.

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Language：Japanese   Publisher：フジタ技術研究所  

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Language：Japanese   Publisher：土木学会  

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Language：Japanese   Publisher：土木学会  

DOI： 10.2208/jscej.1997.560_107

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J-GLOBAL

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Language：Japanese  

DOI： 10.2208/jscej.1997.561_119

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J-GLOBAL

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The beam-column method is usually applied to retaining wall design. But, there are some cases that prediction by using this method doesn&#039;t simulate the trend observed by the in-situ measurements, because the procedure for determining computational parameters is not well defined.&lt;br&gt;In this paper, we performed the back analysis by using the measurement data during excavation work at 10 construction site in Osaka, and estimated the lateral pressure acted on the wall and coefficient of subgrade reaction that is input parameters of the beam-column method. As a result it was found that the lateral pressure and coefficient of subgrade reaction depend on displacement of retaining wall.

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The authors had proposed the back analysis method for the estimation of earth pressure or coefficient of subgrade reaction in excavation work, using the extended Kalman filter of control theory. In case of simultaneous estimation of earth pressure and coefficient of subgrade reaction, this procedure is unstable.&lt;br&gt;This paper describes the new back analysis considering moment of retaining wall and the external forces as the observation vector for the observation equation. Using this method, earth pressure and coefficient of subgrade reaction can be easily identified and the convergence is developed.

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Language：Japanese   Publisher：フジタ技術研究所  

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Language：Japanese   Publisher：フジタ技術研究所  

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Language：Japanese   Publisher：フジタ技術研究所  

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Language：Japanese   Publisher：フジタ技術研究所  

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Language：Japanese   Publisher：公益社団法人 土木学会  

DOI： 10.2208/proee1957.22.135

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