Babloo Chaudhary

Effects of reinforcement on the performance of breakwater foundation subjected to earthquake loadings

This paper deals with reinforcing technique for foundation of breakwater which provides resiliency to breakwater against earthquakes. Gabions and sheet piles were used in foundation of breakwater as reinforcing measures against earthquake loadings. Shaking table tests were performed to evaluate the effectiveness of the technique under different earthquake loadings, and comparisons were made between conventional and the reinforced foundation. Numerical analyses were also performed to elucidate the mechanism of the reinforcement–soil–breakwater system during earthquakes. The results of this study reveal the advantages of the technique in reducing settlement and horizontal displacement of the breakwater during different earthquake loadings.

Countermeasures for breakwater foundation subjected to foreshocks and main shock of earthquake loading

ABSTRACT Coastal protective structures, such as composite breakwaters, are generally vulnerable to earthquake. It was observed that breakwaters damage mainly due to failure of their foundations. However, the seismically induced failure process of breakwater foundation has not been well understood. This study describes failure mechanism of breakwater foundation as well as a newly developed reinforcing model for breakwater foundation that can render resiliency to breakwater against earthquake-related disasters. Steel sheet piles and gabions were used as reinforcing materials for foundation. The experimental program consisted of a series of shaking table tests for conventional and reinforced foundation of breakwater. Numerical analyses were conducted using finite difference method, and it was observed that the numerical models were capable to elucidate the seismic behavior of soil–reinforcement–breakwater system. This paper presents an overview of the results of experimental and numerical studies of the seismic response of breakwater foundation. Overall, the results of these studies show the effectiveness of the reinforced foundation in mitigating the earthquake-induced damage to the breakwater. Moreover, numerical simulation was used for parametric study to determine the effect of different embedment depths of sheet piles on the performance of breakwater foundation subjected to seismic loading.

Effect of Backfill Reinforcement on Retaining Wall Under Dynamic Loading

This paper presents numerical analysis of a reinforced soil retaining wall under static and dynamic loading. Finite difference programme, FLAC, was used to analyze behaviour of the reinforced soil retaining wall. In the analysis, behavior of soil–wall interaction, soil-reinforcement interaction has been considered. Analyses were conducted using different backfill conditions and loading conditions. The lateral displacement and earth pressure were analysed in order to evaluate the effect of reinforcement on the retaining wall. Comparisons were made between unreinforced (conventional) and reinforced soil retaining wall. The results show that length of the reinforcing layer affects earth pressures as well as lateral displacement significantly. Incremental dynamic earth pressure was affected by length of reinforcing layer.

Behavior of Breakwater Foundation Reinforced with Steel Sheet Piles Under Seismic Loading

Waterfront structures such as breakwater, coastal dike, sea wall, etc., suffer serious damage from the earthquake and tsunami. The breakwaters are designed to protect coastline and seaport from the devastation effect of wave and current of tsunami by absorbing their wave energy and reducing overtopping. The port of Kamaishi (Iwate Prefecture, Japan) suffered heavy causalities due to the Great East Japan Earthquake in March 2011 mainly due to the damage of breakwater mound/foundation which was caused due to collapse of the breakwater. On the other hand, mitigation of compound disaster due to predicted future earthquakes such as Tokai earthquake, Nankai Earthquake, and Tonankai-Nankai Earthquake is a matter of great concern. The stability and safe performance of breakwater is very important for the protection of structures and population living near to coastline. It is, therefore, necessary to develop a new earthquake and tsunami resistant reinforcement technique for breakwater foundations which will make the breakwater resilient against the earthquake and tsunami forces. This paper deals with the development of an effective reinforcement technology for breakwater foundation which provides resiliency to the mound against earthquake. The technique involves use of steel sheet piles and gabion type mound (gravel wrapped up in steel wired mesh), which is effective in preventing breakwater subsidence and horizontal displacement. As a part of the study, a series of shaking table test in 1 g of gravitational field were performed and through the tests, the reinforcement effect by the steel sheet pile and gabion under earthquake loading and its influence on breakwater performance was made clear.

Mitigation of earthquake-induced damage of breakwater by geogrid-reinforced foundation

ABSTRACT A strong earthquake often precedes a tsunami, and a breakwater may settle during the earthquake. Such seismic subsidence of the breakwater may reduce its ability to block the tsunami, and the tsunami may easily enter coastal areas by overflowing it. This study deals with the instability of a breakwater due to an earthquake. In addition, to protect a breakwater from damage caused by an earthquake, a new concept of using geogrid for reinforcing the foundation of a breakwater is introduced. To determine the behavior of unreinforced foundation and to evaluate the effectiveness of the proposed reinforced foundation under different earthquake loadings, a series of shaking table tests were performed. It was observed that the earthquake generated excess pore water pressures and deformations of foundation ground were main reasons of failure of the breakwater. The reinforced foundation was found effective to reduce the earthquake-induced damage of the breakwater, and finally it makes the breakwater resilient against earthquake-induced forces. Numerical simulations were also performed to elucidate the mechanism of reinforcement–breakwater–soil–water system under different earthquake loadings.

Dynamic behaviour of saturated sandy soil reinforced with non-woven polypropylene fibre

This research presents results of shaking table tests which were carried out on the soil reinforcement with randomly distributed synthetic fibres. The main scope of the study is to investigate the reliability and performance of polypropylene fibres in improving liquefaction resistance of loose sand prone to liquefaction. Dynamic properties of reinforced sand such as shear modulus and damping ratio were obtained, analysed and compared to those of unreinforced sand. The results indicated that shear modulus and damping ratio are increased by adding fibrous materials as a reinforcement to the host sandy soil. However, no meaningful improvement was achieved by reducing pore water generated during shaking. Outcomes also demonstrated that liquefaction-induced settlement is slightly higher in reinforced soil when compared to unreinforced soil.