Stability Of Armor Units Research Articles

PentaPod: A new type of concrete armor for coastal protection

This paper explores PentaPod, an invention in concrete armor units developed to protect coastal areas from damage caused by waves and currents. Until now, there hasn't been an armor unit intentionally designed to enhance its stability through connections with neighboring units. PentaPod provides a novel perspective, suggesting that the stability of armor units can be significantly improved not only by having substantial weight and effective interlocking but also by securely connecting them to each other. With this in mind, PentaPod concrete armor can be installed in a random or regular manner without the need for fasteners. Alternatively, it can also be installed regularly in layers with fasteners. Compared to conventional concrete armor installations, the overall stability of structures is significantly improved with interconnected PentaPod, either partially or entirely. In this paper, the results of testing the Stability Coefficient (Kd) for two variations of armor, namely PentaCone and PentaOcta, tested in a Wave Tank are also presented. The objective of this testing is to ascertain the stability coefficient for both variations of armor when installed randomly or regularly without any tying involved. The PentaPod arrangement allows for the implementation of both Grey Protection (using concrete armor) and Green Protection (conservation of mangrove areas) simultaneously, showcasing its versatility and integrated approach to coastal protection.

STABILITY OF ARMOR UNITS COVERING RUBBLE MOUND OF COMPOSITE BREAKWATERS AGAINST A STEADY OVERFLOW OF TSUNAMI

This paper presents a simple and highly accurate stability estimation method for armor units covering breakwater rubble mounds against tsunami overflow. In this method, overflow depth is used to represent the external force. This enables an easier and more robust estimation of the required mass of the armor units than the conventional method based on flow velocity. This method takes into account the influence of the impingement position of the overflow jet and the influence of harbor-side water depth, both of which are important factors for armor stability. Numerical computation is also carried out aiming at the establishment of a stability analysis method for armor units. The validity of the computation method is confirmed by comparing the measured current field. The stability of armor units is investigated by computing the hydraulic force acting on each armor unit.

防波堤を越流する津波に対する港内側マウンド被覆材の安定性に関する研究

防波堤を越流する津波に対する港内側マウンド被覆材の安定性に関する研究

STABILITY OF WIDE TOE BERM BREAKWATER WITH VARYING SEABED SLOPE

ABSTRACT Stability of rubblemound breakwater as a whole depends primarily upon the stability of the individual armour units against the wave attack. The manner in which waves interact with the structure is governed not only by the form of the structure, but also by the seabed slope. In order to study the effect of seabed slope on the stability, hydraulic model tests were conducted on a breakwater section in a wave flume with different seabed slopes of 1: 120 and 1: 50. The tests were conducted with breaking and non-breaking waves with two different water levels and two wave periods. Model studies indicated that the stability of armour units decreases with steeper bed slopes. The results are useful for optimising the design of breakwaters. Simulation of seabed slope in the hydraulic model is crucial in finalising the design of rubblemound breakwater section.

Stability of Armour Units on Rubble Mound Breakwater Under Multi-Directional Waves

An extensive 3D model test program has been performed to study the effects of wave obliquity and multidirectionality on the stability of armour units on rubble mound breakwater. Four types of armour units — dolosse, Accropode, hollow-square and quarry stones were tested under five angles of wave attack (0°, 15°, 30°, 45° and 60°) for both long-crested waves and directional waves. Two wave steepnesses (sop = 0.05 and 0.03) and three directional spreading (s = 10, 40 and ∞) were chosen for the test. A method is proposed to take into account the effects of wave obliquity and multidirectionality on the armour unit stability.

STABILITY OF ARMOR UNITS (SEASUP CONCRETE BLOCK) OF DISCHARGE CHANNEL MOUND IN THE SURF ZONE

A series of hydraulic model experiments are conducted to investigate the stability of armor units using SEASUP concrete block for discharge channel mound in the surf zone. The effect of wave breakig on the stability of the block is noticeable. The stability of the block is influenced by the water velocity (Vmax, V1/10) on the mound.

Design and construction of caisson breakwaters — the Japanese experience

The history of breakwater construction in Japan is reviewed and present design methods of vertical breakwaters are discussed in terms of wave forces and breakwater stability. Current design techniques of vertical breakwaters in Japan are the culmination of many years of experiences and practical research in this field. The Goda formula, which accurately predicts the design wave forces under most conditions of vertical breakwaters, is an excellent aid in the design of the breakwaters. Under certain conditions, excessive impulsive forces due to the action of breaking waves are exerted on the upright section. Such conditions must be minimized in the design of vertical breakwaters, and the adoption of vertical breakwaters covered with wave dissipating concrete blocks or the wave dissipating caisson breakwaters offer potential solutions of this problem. The bearing capacity of rubble mound foundation and the stability of armor units are also discussed.

Discussion of “ Stability of Armor Units on Composite Slopes ” by Nobuhisa Kobayashi and Brian K. Jacobs (September, 1985, Vol. 111, No. 5)

Discussion of “ <i>Stability of Armor Units on Composite Slopes</i> ” by Nobuhisa Kobayashi and Brian K. Jacobs (September, 1985, Vol. 111, No. 5)

Closure to “ Stability of Armor Units on Composite Slopes ” by Nobuhisa Kobayashi and Brian K. Jacobs (September, 1985, Vol. 111, No. 5)

Closure to “ <i>Stability of Armor Units on Composite Slopes</i> ” by Nobuhisa Kobayashi and Brian K. Jacobs (September, 1985, Vol. 111, No. 5)

Stability of Armor Units on Composite Slopes

Riprap and sandbag model tests are conducted in a wave flume to investigate the effects of berm‐type slopes on the stability of armor units and wave runup as compared to uniform slopes. Measurements of wave runup, rundown, wave height, breaker type and the response of armor units under regular wave action are made for each test run. The uniform and composite slope test results are analyzed using a modified Saville's method which accounts for the overall effects of the slope configuration on the stability of armor units and wave runup. A simple analysis procedure based on the proposed method is developed for a preliminary design of a berm configuration. An example computation is made for a composite slope protected with riprap. The berm width, the berm slope and the water depth at the shallowest point of the berm are varied so as to determine the optimal berm configuration for increasing the stability of riprap under the assumed wave conditions.