Tsunami intrusion through port breakwaters enclosed with self-elevating seawalls

Takagi, Hiroshi; Tomiyasu, Ryoichi; Oyake, Tomoyuki; Araki, Taketo; Mori, Kyosuke; Matsubara, Yasuhiro; Ninomiya, Yohei; Takata, Yoshifumi

doi:10.1016/j.oceaneng.2020.107028

Cited by 10 publications

(4 citation statements)

References 10 publications

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“…It is consistent with the variation of the arch height and arch span of the mulberry straw arch. Many scholars propose to use different plant material as revetment structure, such as timber piles, bamboo and Melaleua fences [22][23][24][25][26][27]. The protection systems with timber piles are often seen on the riverbank revetment, particularly in developing countries such as Thailand [22,24] and Vietnam [23] among many others.…”

Section: Field Monitoring Resultsmentioning

confidence: 99%

“…The protection systems with timber piles are often seen on the riverbank revetment, particularly in developing countries such as Thailand [22,24] and Vietnam [23] among many others. Takagi et al [22,24,25] described in detail the use of timber piles for the bank protection in a coastal city of Vietnam. Hua et al [2] summarized the specific engineering cases of timber pile revetment in China.…”

Section: Field Monitoring Resultsmentioning

confidence: 99%

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Field Application of Mulberry Straw Arch in Ecological Bank Revetment

Yu¹,

Liu²,

Hua³

et al. 2022

Journal of Renewable Materials

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With the growing level of awareness and increasing demand for environmental protection, timber pile revetments with significant ecological effects have experienced increasingly wide application in China. The current timber pile revetment system has two problems: continuous dense piles have high construction costs and require large timber consumptions, while the discrete pile-bamboo fence systems have poor retaining effects. Considering these problems, an original revetment structure form is proposed: a discrete pile-mulberry straw arch structure. To investigate the mechanical properties of the mulberry straw, some mechanical tests are conducted on mulberry straw and its arch structure. It is found that the average compressive strength of mulberry straw is 2.30 MPa, the bending strength is 20.08 MPa and the shear strength is 2.99 MPa; considering the structural characteristics of arches, mulberry straw arches have a high bending strength, which affords immense potential for their application in revetment structures. Furthermore, by doing field study of the discrete timber pile-mulberry straw arch structure for bank revetment, it is found that the arch height of the mulberry straw arch changes 1.4-1.6 cm after 489 d observation. The soil settlement before the straw arch is 0.13-0.18 cm and the settlement of the pile is 0.66-0.72 mm. Compared with bamboo fence structure, the cost of using mulberry straw arch structure as revetment material can save up to 27.07%. Therefore, the discrete timber pile-mulberry straw arch has a rational and stable structure that provides effective support for protecting the riverbank and the toe of gentle slopes and effectively prevents the collapse of bank slopes in the rear. The new revetment structure proposed in this paper has significant ecological and economic effects, is easy to construct and feasible for standard production, and consequently has great application potential.

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Section: Field Monitoring Resultsmentioning

confidence: 99%

Section: Field Monitoring Resultsmentioning

confidence: 99%

Field Application of Mulberry Straw Arch in Ecological Bank Revetment

Yu¹,

Liu²,

Hua³

et al. 2022

Journal of Renewable Materials

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“…Previous studies have analyzed the dynamic characteristics of offshore platforms [ 5 , 6 ], summarized the key technologies of offshore platforms [ 7 ], proposed that one of the most relevant cost items is the floating substructure [ 8 ], and presented the fuzzy control method as an alternative solution for the installation platform [ 9 ]. Takagi proposed an innovative jack-up seawall as an effective countermeasure to protect the port and its hinterland from tsunamis [ 10 ]. Feng designed a control strategy and algorithm according to the characteristics that the lifting platform needs to display in order to carry the test body, and realized safe and reliable remote control based on the specific motion conditions [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Research on Pneumatic Control of a Pressurized Self-Elevating Mat for an Offshore Wind Power Installation Platform

Cui,

Shi,

Lin

et al. 2023

Sensors

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Efficient deep-water offshore wind power installation platforms with a pressurized self-elevating mat are a new type of equipment used for installing offshore wind turbines. However, the unstable internal pressure of the pressurized self-elevating mat can cause serious harm to the platform. This paper studies the pneumatic control system of the self-elevating mat to improve the precision of its pressure control. According to the pneumatic control system structure of the self-elevating mat, the pneumatic model of the self-elevating mat is established, and a conventional PID controller and fuzzy PID controller are designed and established. It can be seen via Simulink simulation that the fuzzy PID controller has a smaller adjustment time and overshoot, but its anti-interference ability is relatively weak. The membership degree and fuzzy rules of the fuzzy PID controller are optimized using a neural network algorithm, and a fuzzy neural network PID controller based on BP neural network optimization is proposed. The simulation results show that the overshoot of the optimized controller is reduced by 9.71% and the stability time is reduced by 68.9% compared with the fuzzy PID. Finally, the experiment verifies that the fuzzy neural network PID controller has a faster response speed and smaller overshoot, which improves the pressure control accuracy and robustness of the self-elevating mat and provides a scientific basis for the engineering applications of the self-elevating mat.

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“…A typical application of the dam-break flow test in coastal engineering is the examination of tsunami forces acting on a fixed near-shore or inland structure, such as breakwaters, coastal dikes, oil storage tanks, self-elevating seawalls, and general buildings. Relatively light-weight objects or objects subjected to a buoyancy force, such as armor brock, shipping containers, and cars, are often tested to investigate scatter or displacement caused by a tsunami impact [1][2][3][4][5][6][7]. In addition, scouring due to strong flows can be investigated in a dam-break flume [8,9].…”

Section: Introductionmentioning

confidence: 99%

Stochastic Uncertainty in a Dam-Break Experiment with Varying Gate Speeds

Takagi

Furukawa

2021

JMSE

Self Cite

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Uncertainties inherent in gate-opening speeds are rarely studied in dam-break flow experiments due to the laborious experimental procedures required. For the stochastic analysis of these mechanisms, this study involved 290 flow tests performed in a dam-break flume via varying gate speeds between 0.20 and 2.50 m/s; four pressure sensors embedded in the flume bed recorded high-frequency bottom pressures. The obtained data were processed to determine the statistical relationships between gate speed and maximum pressure. The correlations between them were found to be particularly significant at the sensors nearest to the gate (Ch1) and farthest from the gate (Ch4), with a Pearson’s coefficient r of 0.671 and −0.524, respectively. The interquartile range (IQR) suggests that the statistical variability of maximum pressure is the largest at Ch1 and smallest at Ch4. When the gate is opened faster, a higher pressure with greater uncertainty occurs near the gate. However, both the pressure magnitude and the uncertainty decrease as the dam-break flow propagates downstream. The maximum pressure appears within long-period surge-pressure phases; however, instances considered as statistical outliers appear within short and impulsive pressure phases. A few unique phenomena, which could cause significant bottom pressure variability, were also identified through visual analyses using high-speed camera images. For example, an explosive water jet increases the vertical acceleration immediately after the gate is lifted, thereby retarding dam-break flow propagation. Owing to the existence of sidewalls, two edge waves were generated, which behaved similarly to ship wakes, causing a strong horizontal mixture of the water flow.

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Tsunami intrusion through port breakwaters enclosed with self-elevating seawalls

Cited by 10 publications

References 10 publications

Field Application of Mulberry Straw Arch in Ecological Bank Revetment

Field Application of Mulberry Straw Arch in Ecological Bank Revetment

Research on Pneumatic Control of a Pressurized Self-Elevating Mat for an Offshore Wind Power Installation Platform

Stochastic Uncertainty in a Dam-Break Experiment with Varying Gate Speeds

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