JaLCDOI 10.18926/fest/11639
FullText URL 001_193_198.pdf
Author Shimada, Kiyoshi| Nishimura, Sin-ichi| Fujii, Hiroaki|
Abstract This paper presents a new method for prediction of consolidation settlements of soft grounds. The method is based on the theoretical result which shows that the settlement velocity of soft grounds non-improved or improved with sand drains decreases exponentially with time. Final settlements can be easily derived from the regression analysis for the relationship between the elapsed time and the observed settlement velocity. The method has advantages of its simplicity and capability to give the satisfactorily good estimate of the consolidation settlements, and also the support of the theoretical background.
Keywords consolidation settlement prediction soft ground sand drains one-dimensional consolidation
Publication Title 岡山大学環境理工学部研究報告
Published Date 1996-03
Volume volume1
Issue issue1
Start Page 193
End Page 198
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002314033
JaLCDOI 10.18926/fest/11636
FullText URL 001_181_192.pdf
Author Fujii, Hiroaki| Narita, Mutsuya| Cheng Chin Thai| Shimada, Kiyoshi| Nishimura, Shinichi| Ofori Emanual|
Abstract This paper describes the prediction of seepage in the impervious zones of six embankment dams by seepage analysis. In addition, by making use of the available monitored pore water pressure data of the first filling of reservoir, back analysis was carried out to estimate the best fit seepage parameters. The estimated parameters were used for further prediction of pore water pressures in subsequent monitored durations with reasonable accuracy. The accuracy of prediction was evaluated quantitatively by the prediction difference and error index. The results show that the error indices in the upstream sides of the impervious zones are smaller than those in the downstream sides.
Keywords Unsaturated soils fill dams pore water pressure back analysis FEM
Publication Title 岡山大学環境理工学部研究報告
Published Date 1996-03
Volume volume1
Issue issue1
Start Page 181
End Page 192
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002313591
JaLCDOI 10.18926/fest/11612
FullText URL 002_107_120.pdf
Author Fujii, Hiroaki| Ofori Emmanuel| Shimada, Kiyoshi| Nishimura, Shin-ichi|
Abstract This paper discusses a numerical model that can be used to optimize the installation in a zoned type and a homogeneous type fill dam. Before installation in a real dam to evaluate dam behavior, numerical model described in this paper is carried out on a prototype dam to check the optimum installation, using cross arm measurements. Three cross arm installations at the upstream, the core and downstream to measure displacements are considered. The installation options considered are three cross arm combinations for best installation to verify the safety of dams and to reduce cost. Finite element method is used for generating the displecement field in a linear elastic numerical model. The generated data is used as an input data in the back analysis to check the adequacy of each installation option.
Publication Title 岡山大学環境理工学部研究報告
Published Date 1997-01-10
Volume volume2
Issue issue1
Start Page 107
End Page 120
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002313925
JaLCDOI 10.18926/fest/11591
Title Alternative Evaluation of Liquefaction Resistance by In-situ Testing and Its Application to Reliability Design
FullText URL 005_145_151.pdf
Author Nishimura, Shin-ichi| Shimizu, Hideyoshi| Fujii, Hiroaki| Shimada, Kiyoshi|
Abstract A calculation method of probability of liquefaction is proposed in this paper. The spatial variability of soil parameters for the dynamic shear strength, i.e., N-values, median grain size, fines contents, and the statistical characteristics of the earthquake frequency are considered in the analysis. The standard penetration test (SPT) is convenient to estimate the spatial variability of the dynamic shear strength and mainly used in this study. Furthermore the determination of dynamic shear strength based on Swedish weight Sounding test also introduced here, because it is the simpler test than SPT. While the statistical model of the earthquake frequency is determined based on the record of historical earthquakes. Using this method the probability of liquefaction is calculated. The sand compaction pile method is considered for the ground improvement against the liquefaction. Finally, the relationship between the sand replacement rate and the probability of liquefaction is clarified.
Keywords probability of liquefaction reliability design spatial variability of soil parameters statistical model of earthquake frequency dynamic shear strength
Publication Title 岡山大学環境理工学部研究報告
Published Date 2000-02-29
Volume volume5
Issue issue1
Start Page 145
End Page 151
ISSN 1341-9099
language 日本語
File Version publisher
NAID 120002314022
JaLCDOI 10.18926/fest/11574
FullText URL 003_127_134.pdf
Author Shimada, Kiyoshi|
Abstract This paper discusses the shear strength and volume change characteristics of a loose Fraser River sand. Suction-controlled simple shear tests were carried out for the unsaturated sand. Drained tests for the saturated sand were also carried out for the comparison with the unsaturated sand. The increase of the shear strength of the sand with the matric suction is very small and there is almost no increase of that over 20 kPa of the matric suction. The suppression effect of the matric suction on the volume change bahavior during shear is small, and the degree of dilation increases with the increase of the matric suction.
Keywords unsaturated sand shear strength simple shear test matric suction volume change dilatancy
Publication Title 岡山大学環境理工学部研究報告
Published Date 1998-01-14
Volume volume3
Issue issue1
Start Page 127
End Page 134
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002313902
JaLCDOI 10.18926/fest/11528
Title Alternative Damage factors analysis for small embankment dams due to the Hyogoken-Nambu earthquake special to Hokudan Town
FullText URL 007_055_074.pdf
Author Fujii, Hiroaki| Kunimasa, Kana| Nanba, Akiyo| Yokomizo, Takayuki| Nishimura, Shin-ichi| Shimada, Kiyoshi| Hori, Toshio| Nishiyama, Tatsuro| Wakitani, Yoshiaki|
Abstract This study was performed to clarify which factors affected damage to take-ike (small embankment dams for irrigation in Japanese) of Hokudan Town on Awaji Island in western Japan due to Hyogoken-Nambu earthquake. Multivariate and ordinary statistical analysis were carried out using documentary data (181 damaged and 328 undamaged dams), and ordinary one was done for the results investigated in situ. The model for the multivariate analysis was created with 13 items and 94 categories for 4 groups (Location, Geology Structure, and History of Dam). As a result, the factors causing to damage for dam are (1) the nearest fault (Nojima, Mizukoshi and D2), (2) embankment volume (the larger the more), (3) angle of crest axis to epicenter (diagonal and normal), (4) distance to the nearest fault (less than 500 m), (5) distance to the epicenter (8 to 14 km which almost agree to the location of seismic intensity 7 JMA), (6) play view of dam axis (3 or 4 axes), (7) angle of crest axis to nearest fault (diagonal and normal), (8) elevation of dam site (over 100 m), (9) surface geology of dam site (non-cohesive soil), (10) era of construction (prior to 1891), and (11) soil properties of embankment (constructed of sand, smaller penetration resistance).
Keywords Earth dam earthquake damage site investigation statistical analysis case study
Publication Title 岡山大学環境理工学部研究報告
Published Date 2002-03-22
Volume volume7
Issue issue1
Start Page 55
End Page 74
ISSN 1341-9099
language 日本語
File Version publisher
NAID 120002314039