Author Maeno, Shiro|
Published Date 1986-11-01
Publication Title 岡山大学環境管理センター報
Volume volume8
Content Type Others
JaLCDOI 10.18926/15836
FullText URL Mem_Sch_Eng_OU_21_1_81.pdf
Author Nago Hiroshi| Maeno Shiro|
Abstract Under the attack of storm waves, there are many destructions of coastal structures due to scouring, sinking and sliding. These types of destructions are considered to be in close relation to the dynamic behavior of sand bed around the structures. In this study the characteristics of pore water pressure and stresses in the sand bed around a breakwater under the attack of superposed waves are treated theoretically. The results show that during the crest or the trough being in front of the structure the strength of sand bed around the structure decreases notably and the unstable zone will occur.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1986-11-15
Volume volume21
Issue issue1
Start Page 81
End Page 91
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307224
JaLCDOI 10.18926/15822
FullText URL Mem_Sch_Eng_OU_20_2_35.pdf
Author Nago Hiroshi| Maeno Shiro|
Abstract Under the attack of storm waves, there are many destructions of coastal structures in the forms of sinking and sliding. These types of destructions will be in close relation to the dynamic behavior of sand bed around the structures. From this point of view, in this paper, we investigate the characteristics of the pore water pressure and effective stresses in the highly saturated sand bed under oscillating water pressure theoretically. The results indicate that the oscillating water pressure induce the notable drop of strength of sand bed around the structure under certain condition.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1986-02-28
Volume volume20
Issue issue2
Start Page 35
End Page 45
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307664
JaLCDOI 10.18926/15819
FullText URL Mem_Sch_Eng_OU_17_1_61.pdf
Author Maeno Shiro| Nago Hiroshi|
Abstract In this paper the liquefaction of sand bed under oscillating water pressure are treated as a basic study of the prevention works against the scouring around the hydraulic structures. The results of the former resurch show that the occurrence of the liquefaction depends on both properties of the oscillating water pressure and of the sand layer. Considering the latter properties, that is, the resistivity against the liquefaction increases with the increase of the permeability of the sand bed, we propose the displcement method as one of the prevention works, which is a method to displace the upper layer of the sand bed by the sand with large permeability. The effects of this method are investigated theoretically and experimentally. By the experimental study, it is shown that the proposed displacement method has the apparent effect to prevent the liquefaction. The experimental results are explained fairly well by the theoretical analysis based on the theory of the flow through the elastic porous media.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1983-02-25
Volume volume17
Issue issue1
Start Page 61
End Page 71
ISSN 0475-0071
language 英語
File Version publisher
JaLCDOI 10.18926/15783
FullText URL Mem_Sch_Eng_OU_19_1_13.pdf
Author Nago Hiroshi| Maeno Shiro|
Abstract In this paper the theoretical method to analyse the pore water pressures in the sand bed under the oscillating water pressure is developed. In the former researchs the validity of the theoretical treatment for the one-dimensional problem has been verified. However, the one-dimensional treatment is not sufficient to obtain the precise informations concerning the many practical problems. From this point of view, in this study, we derive the fundamental equations for the general three-dimensional sand layer under the oscillating water pressure. The validity of this theoretical method is verified by experiments for the twodimensional problems.
Publication Title Memoirs of the School of Engineering, Okayama University
Published Date 1984-11-26
Volume volume19
Issue issue1
Start Page 13
End Page 32
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307347
JaLCDOI 10.18926/15501
FullText URL Mem_Fac_Eng_OU_24_2_67.pdf
Author Nago, Hiroshi| Maeno, Shiro|
Abstract Many hydraulic structures are damaged by under flood flow and storm waves year after year. Many cases of dike and breakwater failure are caused by the suck out of sand from behind the revetment. This type of failure will be in close relation to the dynamic behavior of sand bed around the revetment. In this paper, from this point of view, we investigated the basic characteristics of such sand movement by small model tests and tried to explain the hydro- and soil-mechanical mechanism of this phenomenon theoretically.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-03-29
Volume volume24
Issue issue2
Start Page 67
End Page 78
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307928
JaLCDOI 10.18926/fest/11622
FullText URL 001_121_133.pdf
Author Maeno, Shiro| Yamamoto, Tetsuo| Nago, Hiroshi|
Abstract In this paper the theoretical procedure to analyze the dynamic behavior of highly saturated sand bed around a cylindrical block under the cyclic loading of water pressure is developed. The fundamental equations were derived for the axially symmetric coordinates. Then, the finite element equations were developed to solve these fundamental equations numerically. Finally, the numerical method was verified by experiments.
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 121
End Page 133
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002313416
JaLCDOI 10.18926/fest/11571
FullText URL 005_081_098.pdf
Author Magda Waldemar| Maeno, Shiro| Nago, Hiroshi|
Abstract A dynamic response of a submarine pipeline buried in sandy seabed sediments to water loading generated by harmonically oscillating water-table vertical movements is examined in the present report experimentally and numerically. The aim of small-scale laboratory experiments was: (1) to record time-histories of pipeline vertical displacements, and (2) to observe a shape of slip surface of an overburden sand body involved in breakout together with the pipeline. A parametric study was carried out in order to investigate the influence of two meaningful factors, that is the depth of burial and the specific gravity of pipeline, on a gradual upward displacement of the pipeline. Based on a numerical finite-element 2D-analysis of the hydrodynamic pore pressure and effective stresses oscillations in the pipeline vicinity, an analysis of the pipeline stability potential is presented, in which all the experimental cases tested are verified. All important component forces (e.g., hydrodynamic uplift force) associated with floatation phenomenon of the buried submarine pipeline are considered and quantified.
Keywords submarine pipeline surface waves pore pressure floatation stability
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 81
End Page 98
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002313700
JaLCDOI 10.18926/fest/11567
FullText URL 003_075_095.pdf
Author Magda Waldemar| Maeno, Shiro| Nago, Hiroshi|
Abstract The response on sandy seabed sediments to a harmonically oscillating water-table, with a special consideration of the wave-induced pore-pressure oscillations around a pipeline buried in seabed sediments, is studied in the present work experimentally and numerically. The aim of the analysis was: (1) to observe a true distribution pattern of the wave-induced pore-pressure oscillations acting on the pipeline outer surface, and (2) to verify small-scale test results using numerical computations performed for a wide range of saturation conditions of seabed sediments, under the assumption of a compressible two-phase medium compound of the pore-fluid and soil skeleton, as well as a finite thickness of a permeable seabed layer.
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 75
End Page 95
ISSN 1341-9099
language 英語
File Version publisher
NAID 120002313821
Author 前野 詩朗|
Published Date 1993-09-30
Publication Title
Content Type Thesis or Dissertation