リケラボ論文検索は、全国の大学リポジトリにある学位論文・教授論文を一括検索できる論文検索サービスです。

リケラボ 全国の大学リポジトリにある学位論文・教授論文を一括検索するならリケラボ論文検索大学・研究所にある論文を検索できる

リケラボ 全国の大学リポジトリにある学位論文・教授論文を一括検索するならリケラボ論文検索大学・研究所にある論文を検索できる

大学・研究所にある論文を検索できる 「津波越流による海岸堤防陸側地盤での洗掘に関する研究」の論文概要。リケラボ論文検索は、全国の大学リポジトリにある学位論文・教授論文を一括検索できる論文検索サービスです。
リケラボ

コピーが完了しました

URLをコピーしました

論文の公開元へ論文の公開元へ
書き出し

津波越流による海岸堤防陸側地盤での洗掘に関する研究

Takegawa, Naoki 神戸大学

2021.03.25

概要

In the 2011 off the Pacific coast of Tohoku Earthquake, a huge tsunami destroyed many coastal protection facilities, such as seawalls and coastal dikes. As of June 10, 2020, the number of deaths from the Great East Japan Earthquake was 15,899, and more than 90% of the deaths were caused by drowning. This huge tsunami not only caused human casualties, but also devastated coastal dikes and other coastal facilities. The purpose of this thesis is to reduce the damage to human life and social infrastructure caused by tsunami overflow through the scour prediction, countermeasures, and applications on the landward side ground of coastal dikes. This paper is composed of 6 chapters, and the contents and conclusions obtained are shown below.

　Chapter 1 introduces an overview of the 2011 off the Pacific coast of Tohoku Earthquake, the mechanism of dike failure and the necessary considerations for the design of coastal dikes.

　In Chapter 2, small-scale model experiments were carried out to examine the effect of the geogrid as scour countermeasures. Sheet-like (two-dimensional) countermeasures are expected to reduce the cost of constniction. A geogrid placed in the vicinity of a coastal dike reduced the scour area by 90%. Increasing the countenneasure length beyond the dike height has little effect on the scour area in the vicinity of tlie dike. In addition to model experiments, numerical simulations were also performed to evaluate the energy dissipation of tsunamis due to the scour hole. When the reduction effect of the velocity is high, the flow velocity decreases by 30% due to scour holes compared the case without countermeasures.

　Chapter 3 complements the validity of the results obtained in Chapter 2. The effect of geogrids was tested by increasing the external force with a vertical jet and locally reproducing a situation similar to real scale conditions. The effects of mesh size and coverage ratio (the proportion of scour countermeasures per unit area) on the scour were investigated, and it was found that when the ratio between the 85% particle size of the bed material and the mesh size below 1.0, both the scour depth and the maximum pore-water pressure are significantly suppressed. In the most effective cases, tlie sheet-like countermeasures reduced the maximum pore-water pressure and the scour depth, respectively, by 91% and 86%. As for the ground where an upward-hydraulic gradient, in the case using the geogrod, no increase in the scour depth was observed. Conversely, when gravel was used, the maximum scour depth increased by a factor of about 1.6 compared to the bed without the upward-hydraulic gradient. This is because the bearing force of the sand bed against the gravel decreases due to the upward-hydraulic gradient.

　In Chapter 4, predictive equations for the scour length and scour depth are proposed on the basis of the present experimental results and previous studies. In determining the coefficients of the equations, the results of various model experiments (Scale of model experiment: 1/50 - 1/2) were used, and tlie experimental results could be expressed in the predictive equations. A comparison between the predictive equations and the scour holes, which were confirmed during the 2011 off the Pacific coast of Tohoku Earthquake, shows good agreement with the field surveys. Furthermore, equations for the case where foundations are placed at the landward ground behind coastal dikes were also derived. From the coefficients of the predictive equations, the scour length increases about 1.2 times and the scour depth decreases about 0.47 times when the foundation is placed at the ground behind coastal dikes.

　In Chapter 5, a new method is proposed that involves using the erosion effect of the tsunami itself to do the velocity reduction work. This method is to replace a part of the ground in advance with a lightweight material to accelerate the erosion at the time of tsunami attack. When the flow was subcritical, the velocity could not be reduced even if a depression was provided. When the flow was supercritical, the depression that formed changed the flow from supercritical to subcritical, and the flow velocity decreased. Assuming a tsunami overflow to be a constant flow rate, the author predicted the tsunami run-up velocity. Comparing the predicted results with experimental results show that the velocity can be predicted with an uncertainty of approximately 20%. The simple predictive method is considered to be extremely useful given that it would be handled easily by general engineers.

　Chapter 6 summarizes the results of this thesis with the conclusions.

論文の公開元へ

この論文で使われている画像

関連論文

関連論文をもっと見る

参考文献

Aderibigbe, O. O., & Rajaratnam, N. (1996). Erosion of loose beds by submerged circular impinging vertical turbulent jets. Journal of Hydraulic Research, 34(1), 19–33. doi:10.1080/00221689609498762.

Bricker, J. D., Francis, M., & Nakayama, A. (2012). Scour depths near coastal structures due to the 2011 Tohoku tsunami. Journal of Hydraulic Research, 50(6), 637–641. doi:10.1080/ 00221686.2012.721015.

Chaudhary, B., Hazarika, H., Murakami, A., & Fujisawa, K. (2018). Geosynthetic-sheet pile reinforced foundation for mitigation of earthquake and tsunami induced damage of breakwater. Geotextiles and Geomembranes, 46(5), 597–610. doi:10.1016/j.geotexmem. 2018.04.011.

Coastal Development Institute of Technology. (2001). Research and development of numerical wave flume. CDIT Library 12. (in Japanese)

Fukumoto, Y., Sukegawa, H., Iwamae, N., & Ikeya, T. (2012). The 2011 off the Pacific coast of Tohoku Earthquake tsunami hydraulic data observed at Choshi offshore. Journal of Japan Society of Civil Engineers Ser.B2, 69(2), 1–5. doi:10.2208/kaigan.68.1. (in Japanese)

Hager, W., & Bretz, N. (1986). Hydraulic jumps at positive and negative steps. Journal of Hydraulic Research, 24(4), 237–253.

Hatogai, S., Suwa, Y., & Kato, F. (2012). Hydraulic model experiments on scour landward of the coastal dike induced by tsunami overflow. Journal of Japan Society of Civil Engineers, Ser. B2, 68(2), 406–410. (in Japanese)

Hazarika, H., Nishimura, K., & Chaudhary, B. (2015). Model testing on resilient solution for breakwater protection against tsunami. Japanese Geotechnical Society Special Publication, 3(2), 40–44. doi:10.3208/jgssp. v03.j05.

Hjulstrom, F. (1935). Studies of the morphological activity of rivers as illustrated by the River Fyris. Bulletin of the Geological Institution of the University of Uppsala, 25, 221–527.

Honma H. (1940). Coefficient of flow volume on low overflow weir. Doboku Gakkai shi, 26(6), 635–645. (in Japanese)

Iiboshi, T., Maeno, S., Yosida, K., Takata, D., & Yamamura, A. (2015). Effects of landward slope protection and toe protection work shape at coastal dikes on landward bed scouring caused by tsunami overflow. Proceeding of 36th International IAHR World Congress, Hague, Netherlands.

Iwagaki, Y. (1956) Hydrodynamical study on critical tractive force. Transactions of the Japan Society of Civil Engineers, 41, 1–21. (in Japanese)

Izumi, A., & Hori, T. (2017). Centrifugal model tests on dynamic behavior of dike integrated three surfaces. Proceedings of the H29 irrigation, Drainage and rural engineering, Huzisawa, Japan.

Japan Meteorological Agency. (2020). Seismic intensity database. http://www.data.jma.go.jp/svd/eqdb/data/shindo/index.html. Accessed November 16, 2020. (in Japanese)

Jones, W. P., & Launder, B. E. (1973). The calculation of low-reynolds-number phenomena with a two-equation model of turbulence. International Journal of Heat and Mass Transfer, 16(6), 1119–1130.

Kato, F., Suwa, Y., Watanabe, K., & Hatogai, S. (2012). Mechanisms of coastal dike failure induced by the great east Japan earthquake tsunami. Proceeding of 33rd International Conference on Coastal Engineering, Santander, Spain.

Kawasaki, K. (2012). Fundamental characteristics of tsunami and tsunami disaster due to the 2011 off the Pacific coast of Tohoku Earthquake. Japanese Journal of Multiphase Flow, 26(1), 11–18. doi:10.3811/jjmf.26.11. (in Japanese)

Kiri, H., Nakaya, T., Azechi, I., & Matsushima, K. (2015). Effect of the tsunami dissipation facility that modeled a pool at the toe of back slope of the coastal levees. Journal of Japan Society of Civil Engineers, Ser. B1, 71(4), I_1369–I_1374. doi:10.2208/jscejhe.71.I_1369.

Kurakami, Y., Nihei, Y., Kawabe, S., Kikuchi, Y., & Tatsuoka, F. (2013). A new levee type comprising soil to increase resistance against overflow erosion. Geosynthetics Engineering Journal, 28, 265–272. doi:10.5030/jcigsjournal.28.265.

Matsuda, T., Maeda, K., Miyake, M., Miyamoto, J., Sumida, H., & Tsurugasaki K. (2014). Experimental speculation on scour due to jet flow focusing on the soil particle and the soil element scale level. Journal of Japan Society of Civil Engineers Ser.B2,70 (2), l_1041– l_1045. (in Japanese)

Matsuda, T., Yamaguchi, A., Maeda, K., Takagi, K., Tsurugasaki, K., & Miyamoto, J. (2016). Experimental study on scouring the two-layer ground due to jet flow. Journal of Japan Society of Civil Engineers Ser.B2,72 (2), l_1195–l_1200. (in Japanese)

Ministry of Agriculture, Forestry and Fisheries. (2020). Coastal projects. https://www.maff.go.jp/j/nousin/bousai/bousai_saigai/b_kaigan/. Accessed November 16, 2020. (in Japanese)

Ministry of Land, Infrastructure, Transport and Tourism. (2011). Guideline of technical investigation for permitted structure. https://www.mlit.go.jp/river/shishin_guideline/kasen/pdf/kyokakousakubutu_tebiki.pdf. Accessed November 16, 2020. (in Japanese)

Mikami, T., Shibayama, T., & Esteban, M. (2012). Field survey of the 2011 Tohoku Earthquake and tsunami in Miyagi and Fukushima prefectures. Coastal Engineering Journal, 54 (1), 1250011 1–26. doi:10.1142/S0578563412500118.

Mitobe, Y., Adityawan, M. B., Tanaka H., Kawahara, T., Kurosawa, T., & Otsushi, K. (2014a). Experiments on local scour behind coastal dikes induced by tsunami overflow. Proceedings of the 34th International Conference on Coastal Engineering, Seoul, Korea.

Mitobe, Y., Adityawan, M. B., Tanaka, H., Kawahara, T., Kurosawa, T., & Otsushi, K. (2014b). Experiments on scouring behind coastal dikes induced by tsunami overflow. Journal of Japan Society of Civil Engineers, Ser. B1, 70(4), I_1147–I_1152. doi:10.2208/jscejhe.70.I_1147.

Mitobe, Y., Adityawan, M. B., Roh, M., Tanaka, H., Otsushi, K., & Kurosawa, T. (2016). Experimental study on embankment reinforcement by steel sheet pile structure against tsunami overflow. Coastal Engineering Journal, 58(4), 1640018–1. doi:10.1142/S0578563416400180.

Moore, W., & Morgan, C. (1957). The hydraulic jump at an abrupt drop. Journal of the Hydraulics Division, 83(6), 1–21.

Nagasaka, Y., Harry, Y., Nakao, H., Sato, S., Tajima, Y., & Yamanaka, Y. (2012). Study on the erosion mechanisms of soil embankment by tsunamis. Journal of Japan Society of Civil Engineers Series B2, 68(2), I_1331–I_1335. doi:10.2208/kaigan.68.I_1331.

Nakamura, T., & Mizutani., N. (2014). Numerical analysis of tsunami overflow over a coastal dike and local scouring at the toe of its landward slope. Journal of Japan Society of Civil Engineers, Ser. B3, 70(2), 516–521. (in Japanese)

National Police Agency. (2012). The 2011 off the Pacific coast of Tohoku Earthquake and police. https://www.npa.go.jp/archive/keibi/syouten/syouten281/pdf/ALL.pdf. Accessed November 16, 2020.

National Police Agency. (2020). Police activities and damage situation of the 2011 off the Pacific coast of Tohoku Earthquake. https://www.npa.go.jp/news/other/earthquake2011/pdf/higaijokyo.pdf. Accessed November 16, 2020.

Noguchi, K., Sato, S., & Tanaka., S. (1997). Large-scale model experiment of wave overtopping and frontal surface scouring of revetment due to tsunami run-up. Annual Journal of Coastal Engineering, 44, 296–300.

Ohtsu, I., & Yasuda., Y. (1991). Transition from supercritical to subcritical flow at an abrupt drop. Journal of Hydraulic Research, 29(3), 309–328.

Rajaratnam, N., & Ortiz., N. V. (1977). Hydraulic jumps and waves at abrupt drops. Journal of the Hydraulics Division, 103(HY4), 381–394.

Rajaratnam, N. (1981). Erosion by plane turbulent jets. Journal of Hydraulic Research 19 (4): 339–358. doi:10.1080/00221688109499508.

Sawada, Y., Miyake, M., Sumida, H., & Kawabata, T. (2014). Pore water pressure and liquefaction in saturated sand bed induced by tsunami. Irrigation, Drainage and Rural Engineering Journal, 82(2), 113–120.

Sherard, L., & Dunnigan, P. (1989). Critical filters for impervious soils. Journal of Geotechnical Engineering, 115(7), 927–947. doi:10. 1061/(ASCE)0733- 9410(1989)115:7(927).

Takahashi, H., Morikawa, Y., Mori, N., & Yasuda, T. (2015). Centrifuge tests on collapse of concrete-covered levee due to composite forces of overflow and seepage. Journal of Japan Society of Civil Engineers Ser. B2, 68(2), 42–51. (in Japanese)

Takegawa, N., Sawada, Y., Murai, K., & Kawabata, T. (2018). Influence of liquefaction on scour behind coastal dikes due to tsunami overflow. International Journal of Geotechnical Engineering, 12(1), 40–45. doi:10.1080/19386362.2016.1246216.

Takegawa, N., Sawada, Y., & Kawabata, T. (2020). Geogrid-based countermeasures against scour behind coastal dikes under tsunami overflow. Marine Georesources & Geotechnology, 38(1), 64–72. doi:10. 1080/1064119X.2018.1552998.

Tanaka, N., & Sato, M. (2015). Scoured depth and length of pools and ditches generated by overtopping flow from embankments during the 2011 great east Japan tsunami. Ocean Engineering, 109, 72–82. doi:10.1016/j.oceaneng.2015.08.053.

Tanimoto, R., & Tokida, K. (2012). Study on structure of dug pool eroded by tsunami flood and its tsunami-reduction function. International Symposium on Earthquake Engineering, 1, 143–150.

Tanimoto, R., Tokida, K., Kitagawa, H., & Araki, S. (2012). Investigation on resistance of earth bank and reduction by dug pool against tsunami. Journal of Japan Society of Civil Engineers Ser.B2, 8(2), I_316–I_320. doi:10.2208/kaigan.68.I_316. (in Japanese) The OpenFOAM Foundation. (2019). OpenFOAM User Guide version 7.

Tokida, K., & Koizumi, K. (2011). Lessons from tsunami damage and discussion on hard countermeasures part1. Geotechnical Engineering Magazine, 59(8), 36–42. (in Japanese)

Tokida, K., & Tanimoto, R. (2012). Lessons and views on hardware countermeasures with earth banks against tsunami estimated in 2011 great east Japan earthquake. Proceedings of the One Year after 2011 Great East Japan Earthquake International Symposium on Engineering Lessons Learned from the Giant Earthquake, 9, 1–12.

Tokida, K., & Tanimoto, R. (2014). Lessons for countermeasures using earth structures against tsunami obtained in the 2011 off the Pacific coast of Tohoku Earthquake. Soils and Foundations, 54(4), 523–543. doi:10.1016/j.sandf.2014.07.001.

Tonkin, S., Yeh, H., Kato, F., & Sato, S. (2003). Tsunami scour around a cylinder. Journal of Fluid Mechanics, 496, 165–192. doi:10.1017/ S0022112003006402.

United States Geological Survey. (2020). 20 largest earthquakes in the world. https://www.usgs.gov/natural-hazards/earthquake-hazards/science/20-largest- earthquakes-world?qt-science_center_objects=0#qt-science_center_objects. Accessed November 16, 2020.

Yeh, P. H., Chang, K. A., Henriksen, J., Edge, B., Chang, P., Silver, A., & Vargas, A. (2009). Large-scale laboratory experiment on erosion of sand beds by moving circular vertical jets. Ocean Engineering, 36(3–4), 248–255. doi:10.1016/j.oceaneng.2008.11.006.

参考文献をもっと見る

全国の大学の
卒論・修論・学位論文
を
一発検索！

この論文の関連論文を見る