V Sundar

In this paper, the performance of caisson embedded in a soft marine clay has been brought out through the results obtained from tests carried out on model caissons subjected to both static and cyclic loading. The load-ground level deflection curves and the variations in lateral earth pressure with depth are presented and discussed for the cases of static, cyclic and post cyclic static lateral loading for the load eccentricity ratio (e/D) of 2 and caisson embedment ratios (L/D) of 2,3 and 4. Under cyclic loading with cyclic load ratios (CLR) up to 0.6, the lateral capacity of caisson is governed by static loading. With the increase in cyclic load ratio, there is in an increase in the lateral passive earth pressure. However, at higher cyclic load ratios, there is a significant increase in the lateral deflections. Based on the results of the investigation, it is suggested that the seawalls can be formed out of contiguous caissons installed in a line and these walls can be designed for cyclic load ratios up to 0.6 with suitable embedment ratios.

The measured wave elevation and the corresponding two horizontal velocity components of in-line and transverse directions at eight different locations across a bar in a groin field off the East Frisian Island off Norderney at the North Sea Coast have been analysed. The variation of the wave and the velocities spectra within the groin field is reported. The waves and their kinematics are seldom linear in nearshore waters. In this paper, the results obtained through an attempt to study the asymmetries in the wave elevation and the in-line velocity time histories are reported. The probability density of the asymmetries are drawn along with theoretical Rayleigh and Weibull distributions. The variation of the different asymmetry factors within the groin field is discussed. © 1994.

This study aims to explore the site-specific impact of coastal structures on the stability of the shoreline. For this study, the shoreline data were collected with higher-order accuracy along a few vulnerable stretches of the coast in the vicinity of hard structures such as Seawalls, Groyne, Breakwater, and Training walls along the southeast and southwest coasts of India. All the field collected shoreline data were analysed with statistical measures using DSAS (Digital Shoreline Analysis System) tool of ArcGIS software. The presence of shore connected coastal structures dictates the sedimentation process in its purlieu. The observed average rate of erosion and accretion in the adjoining coastlines are −5.7 m/yr and +4.92 m/yr, respectively. The field measurements from the present study would provide an effective base for the planning and implementation of coastal structures near the studied area, as well as to adopt a better methodology for coastal impact assessment. Most of the well-planned and executed hard engineering structures have yielded desirable results and benefit for the local coastal communities.

This chapter describes a coastal and marine data information system that can be used for Maritime Spatial Planning. The system takes advantage of Internet mapping and web services technology to publish data as maps. These maps are created dynamically and enable the visualization of a diverse and growing collection of environmental data. Capabilities of the system include (i) visualization of environmental parameters on 2D maps; (ii) visualization of location-specific depth profiles of selected parameters; (iii) time animation of grids of environmental parameters and (iv) preparation of digital elevation and cultural object data sets for 3D terrain visualization (Durairaju et al., 2003, 2010). The function and interaction between key components of the system are described to illustrate the working of the system. The use of a mature map publishing engine greatly eased the development of these capabilities into a web-based system.

The submerged semicircular breakwater (SBW) is mainly adopted to prevent beach erosion and to reduce the incident wave energy on its leeside, if it is used in front of a vertical breakwater. In addition, it facilitates the premature wave breaking, which in turn causes the reduction in wave energy. The dynamic pressures and forces exerted on the submerged SBW with 7%, 11%, and 17% of the exposed surface area with perforations on its seaside due to regular waves were measured. The hydrodynamic characteristics such as variations in the dimensionless pressures and forces, reflection and transmission coefficients on the semicircular caisson as a function of scattering parameter for three different water depths are presented and an optimum depth of submergence is arrived. The results on the above stated variables for seaside perforated SBWs are compared with the results of an impermeable SBW to study the effect of perforations. Copyright © 2010 by ASME.

The dynamics of multiple floating structures have been studied using the finite element method. The emphasis is on the hydrodynamic behaviour of multiple bodies under a multi-directional wave field. A two-dimensional numerical model has been adopted to evaluate hydrodynamic coefficients and forces in an oblique wave field. The responses in sway, heave and roll modes are reported. The linear filter technique is then used to extrapolate the responses under directional waves. The effect of mean wave direction and directional homogeneity on the hydrodynamic behaviour of the structure is studied. Based on the present study, it is found that the two-dimensional model is applicable to investigate the wave-structure interaction problems of the type herein considered. (C) 2000 Elsevier Science Ltd. All rights reserved.

Shorelines experience significant changes near a coastal structure and around the confluence of a river and the sea. Field investigation and site data collection by the latest technologies for the detailed data collection would pave the way for the interpretation of the morphological changes close to the real scenario, which is essential for an efficient and sustainable coastal protection planning and coastal zone management. This paper deals with shoreline on either side of the mouth of the Arasalar River draining into the Bay of Bengal with a year-long (March 2018 to February 2019) continuous shoreline assessment during which GAJA cyclone made its landfall on 16 November 2018 along the Karaikal coast of Union Territory of Puducherry located on the southeast coast of India. A pair of training walls effectively keeps the mouth from silting, thereby allowing free passage of vessels. This study aims to understand the seasonal variation coupled with the severe cyclonic impact on the southeast coast of India. Monthly spring shoreline and cross-shore profiles during low tide and high tide were collected, including post-cyclone field data. The results discuss the erosion and accretion pattern of the sediment processes adjacent to the training walls and cyclone effects.

The experimental investigation on dynamic pressure and run-up over a vertical faced seawall and a curved face seawall given in Coastal Engineering Manual suggested by US ARMY CORPS were placed over a bed slope of 1 in 30 and subjected to the action of Cnoidal waves. The results of both the models were compared and discussed. © 2010 World Scientific Publishing Co. Pte. Ltd.

A detailed three-dimensional laboratory investigation on hydrodynamic performance of an array of oscillating water column (OWC) devices, combined with offshore detached breakwater (ODBW) subjected to oblique wave incidence was studied. A Froude scale of 1:20 was chosen for integrating five similar devices of OWC to the ODBW (OWCBW) and a series of experiments was carried out in a shallow wave basin for angle of wave approaching between 90 0 and 70 0 with reference to the front face of the structure with an angular decrement of 10 0 . The hydrodynamic performance was studied in terms of front wall outside pressure, wave amplification, air pressure, capture width, and relative capture width. The convergence of water waves due to three-dimensional effects concentrates high amount of energy in front of the array of OWCs for normal wave incidence. It makes a system to absorb larger amount of wave power of about 1.12 times of the given input power at the natural frequency of the system. This confirms that the array of OWC devices, exhibits better performance than in isolation. The performance of the system reduces with angular decrement due to peak of the wave front reaches the line front of OWCBW in different time along with wave dissipation over the breakwater. The natural frequency of the system was found to be lying in the vicinity of d/L p of 0.12 and unaltered for different angles of wave incidence.

An Explicit Finite Element Method has been applied to simulate the 2004 Great Indian Ocean Tsunami (IOT). The Sperical Shallow Water Equations (SSWE) is used to model the oceanic flow. The domain comprising of Bay of Bengal, Arabian Sea and Indian Ocean has been considered for simulation with an initial disturbance resembling the type and location of the 2004 IOT. The Wave elevations and its deformations have been depicted in the results. The wave heights obtained from the numerical simulation have been compared with the signature data for the Tamil Nadu Coast. The Effect of coriolis force on tsunami has also been studied and reported in this paper.