Coastal Construction Research Articles

Comparison of resistance to damage of unalloyed carbon steels under the influence of hydrogen

One of the most commonly used construction material in industry is unalloyed steel S235 and S355. These types of steel are used for construction of ships, bridges, coastal construction, welded tanks, and in buildings. Due to the operating conditions, these types of steel may undergo hydrogen degradation in the process of manufacturing of welded structures or when operating the structures. This paper presents the results of study into resistance of selected types of non-alloy structural steels to hydrogen degradation. Tests were carried out to determine changes in mechanical properties in the static trials of stretching without hydrogen, and after saturation with hydrogen. Parallel fractographic and electrochemical studies were carried out. Hydrogen saturation was carried out at the time from 3. up to 24. hours in a solution of 0.1N H2SO4 with the addition of 2 mg/dm3 arsenic oxide (III) at an electric current density of 20 mA/cm2. The results of the tests have shown that the impact of hydrogen on the tested steels S235JR and S355J2 leads to a significant deterioration in their mechanical and electrochemical properties. At comparable concentrations of hydrogen, steel S235JR is less susceptible to hydrogen degradation and has greater corrosive resistance measured in 3% NaCl solution, in comparison with steel S355J2.

The assessment of waters ecological state of the Crimea coastal near high-rise construction zones

The relevance of our study is determined by the significant level of coastal sea waters pollution by sewage near high-rise construction zones, which determines the violation of the sanitary and hygienic of sea waters ‘characteristics and limits the possibilities for organizing recreational activities. The purpose of this study is to identify the ecological state of the marine aquatic area by the example of the Western Crimea near high-rise construction zones. The studies confirmed that the recreational and coastal area wastewater is intensely mixed with seawater, as a result, the pollution in the coastal strip of the sea in the area of deep water discharges sharply decrease. This happens because of water rapid rise to the surface and under the influence of the continuous movement of sea water huge masses with deep-water discharge, fresh wastewater is actively mixed with sea water. However, with no doubt, it is inadmissible to discharge sewage into the sea directly from the shore, but only at the estimated distance from the coast. The materials of the article can be useful for the management bodies and organizations involved in monitoring the quality of the coastal zone of the sea, teachers and students of higher educational institutions when assessing the ecological situation of the territories.

Liquefaction analysis of abrasion protection structure in Padang

The liquefaction potential of a soil deposit is an important aspect to consider the stability of structure due to the earthquake. The liquefaction may also contribute to the safety of coastal constructions. The assessment of liquefaction potential can be started by having the physical properties of sandy soil that include grain size and density. Those parameters had known to give effects to the liquefaction resistance. Those physical properties of sand soil associated with liquefaction resistance must be tested in the laboratory. A case study of a real construction design in Padang, Indonesia is discussed here. The liquefaction potential was assessed using the Density-Grain size methods. The suggested solution to treat those problems is then provided. The compaction treatment to reach a certain relative density before the construction on site may avoid the liquefaction potential and save the coastal structure.

The Benefit of Wind Distribution Analysis for Coastal Construction Design in East Java Province

To create a safe and durable coastal structures design, a comprehensive data including minimum, maximum, and significant sea wave’s height are needed. Normally, to obtain such massive data, engineers need to elaborate specialized consultant to carry out direct measurement on site, which typically consumes enormous financial resources and involves exceptionally rare experts. In such case, engineers can use a set of 10 to 20 years’ wind data as a substitution. The suggested duration is expected to ensure that the set of data has sufficient information, which includes extreme wind speed and its fluctuation along the respective years. Therefore, it is common to adopt available data at the nearest wind stations, such as airports and harbors, to estimate the wind features on site. This paper presents a normative wind speed distribution model based on 16 years’ wind data at a location obtained from National Oceanic and Atmospheric U.S. Department of Commerce (NOAA). The outcomes of the research show that the maximum sea wave height prediction in Sidoarjo Regency East Java with respect to analytical and graphical method are 0,465 m and 0,840 m, respectively. The results are considered satisfactorily reliable to be used as primary data to design coastal structures.

Implementation of porous material through eco-tech for deep cement–soil mixing

ABSTRACTIn this study, a mixture design test and case study were performed in a laboratory and on field, respectively, to evaluate the applicability of an eco-friendly porous media binder (CMD-SOIL) using desulfurized ash left behind in a power plant by waste. The deep cement-soil mixing method using desulfurization ash (CMD-SOIL) is effective as a new material that can be used to cope with the cement used in the conventional deep cement mixing method. In the laboratory-based mixture design tests, the uniaxial compression strength of CMD-SOIL was up to 1.14 times higher than that of slag cement when varying water content, mixing rate, and water/binder ratio. In addition, the CMD-SOIL shown strength of up to 1.22 times higher than that of oyster shell content and up to 1.36 times higher than that of a floating soil mixture. The case study showed that the uniaxial compression strength ratio (λ) of the improved porous media of the field to that of the laboratory (qu(field)/qu(lab)) was 0.77, similar to the general rate, in the design criterion. Therefore, the CMD-SOIL has sufficient strength and economical effect on the coastal construction, in which the shell layer is mixed with shellfish, or in the application of a construction technique for treating floating soils.

Responses of water environment to tidal flat reduction in Xiangshan Bay: Part I hydrodynamics

Xiangshan Bay consists of a deep tidal channel and three shallow inlets. A large-scale tidal flat has been utilized through coastal construction. To ascertain the accumulate influences of these engineering projects upon the tidal dynamics of the channel-inlets system, this study uses FVCOM to investigate the tides and flow asymmetries of the bay, and numerically simulate the long-term variations of tidal dynamics caused by the loss of tidal flats. It was found that the reduction of tidal flat areas from 1963 to 2010 slightly dampened M2 tidal amplitudes (0.1 m, ∼6%) and advanced its phases by reducing shoaling effects, while amplified M4 tidal amplitudes (0.09 m, ∼27%) and advanced its phases by reducing bottom friction, in the inner bay. Consequently, the ebb dominance was dampened indicated by reduced absolute value of elevation skewness (∼20%) in the bay. The tides and tidal asymmetry were impacted by the locations, areas and slopes of the tidal flats through changing tidal prism, shoaling effect and bottom friction, and consequently impacted tidal duration asymmetry in the bay. Tides and tidal asymmetry were more sensitive to the tidal flat at the head of the bay than the side bank. Reduced/increased tidal flat slopes around the Tie inlet dampened the ebb dominance. Tidal flat had a role in dissipating the M4 tide rather than generating it, while the advection only play a secondary role in generating the M4 tide. The full-length tidal flats reclamation would trigger the reverse of ebb to flood dominance in the bay. This study would be applicable for similar narrow bays worldwide.

In-water impact pile driving sound source spectra comparison and the quest for a “Generic Spectrum”

Noise generated from in-water impact pile driving for marine and coastal construction can impact marine mammals. Physiological effects to marine mammals include hearing impairments such as temporary and/or permanent threshold shifts. Because marine mammals’ auditory response to sound levels is frequency-dependent, environmental impact analysis from noise exposure needs to consider noise spectrum in addition to broadband received level. In this study, spectral characteristics of measured noise levels from impact driving of 30-inch steel piles at four locations in Alaska and Washington were compared. Results show for all impact pile driving, most acoustic energies were between 100 and 1,000 Hz. Spectral levels below 100 Hz varied among the locations. Above 1,000 Hz, spectral levels decayed at a rate of 15 dB/decade for the three Alaska sites, but at 30 dB/decade in Washington. Despite these general characteristics, however, there does not seem to be a “generic spectrum” for the 30-inch steel pile impact driving. The variations among the spectral characteristics are likely due to differences in substrate, hammer energy, and bathymetry in different locations.

Mechanical characteristics of undisturbed coral gravel soils: The intergranular void ratio as a common governing parameter

Coral gravel soils are composite soils comprised of large fragments of finger coral and fine particles from silt matrixes. When the amount of coral fragments is small, the mechanical behavior of the coral gravel soil is mainly governed by the silt matrixes, and when the amount of coral fragments is large, the mechanical behavior is mainly governed by the coral fragments. Undisturbed samples, called high-quality samples in the present study, were collected at large-scale coastal construction sites in Okinawa Prefecture and Kagoshima Prefecture, Japan. A series of triaxial CD-tests was conducted in the laboratory to evaluate the mechanical characteristics of coral gravel soils. The test results were examined from various viewpoints to find a common governing parameter for the mechanical behavior of coral gravel soils. It was anticipated that it would be difficult to interpret the mechanical behavior of the high-quality samples in a uniform manner because undisturbed coral gravel soils, in the form of natural sediments, are generally very heterogeneous. To provide a reference for the parametric interpretation of the test results showing the remarkable features of coral gravel soils, such as interlocking and particle crushing, the test data newly obtained for the high-quality samples were compared to the previous test results obtained for reconstituted mixtures having various volumetric percentages of coral fragments. It was found that an intergranular void ratio corresponding to 0.075mm, in which particles finer than a grain size of 0.075mm (i.e., particles of clay and silt) are regarded as voids, can be employed asa useful parameter in evaluating the shear strength of both reconstituted and undisturbed coral gravel soil samples.

The Evolution Analysis of Mechanical Properties of Marine Submerged Concrete Based on GRA

Deterioration of concrete in marine environment and the durability of coastal constructions have raised great concern throughout the world. This work mainly focuses on the compressive strength of concrete in marine submerged environment. Data in previous researches has been collected in this work, which can be used in a particular environment and specific types of concrete for different background, while making it difficult to analysis the influencing factors as a whole. In order to find a relative systematical solution to summarize the data, Grey Relational Analysis method is applied to analysis the mass data collected from previous literates at home and aboard. The purpose of this study is to make a sensitivity analysis of factors influencing the concrete compressive strength in submerged marine environment and guide engineering practice. The results turn out that the initial strength plays the most important role in the final strength after long-term immersion. In addition, the immersing age and cationic ions also affect the final strength of marine concrete. In all, general deterioration exhibits the tendency that upgrading at the very beginning and then descending later.

Disaster Resilience of Low-cost Houses: Case Study of Thua Thien Hue Province, Vietnam

This research documents the post-flood and typhoon conditions of low income housing in the Thua Thien Hue Province, Vietnam, an area prone to extreme flooding in Central Vietnam. The cost of rebuilding houses after a natural hazard has been always a burden for low income households and it often led to the elimination of essential construction practices for disaster resistance. While there has been remarkable improvement in relief and rehabilitation, poor people have been disproportionately vulnerable to extreme events due to their low adaptive capacity and suffered the same damages every year. The research documents existing conditions of low income houses in the Thua Thien Hue province and identifies leading causes of the building failure from the natural disasters. The quality of construction and repairs are assessed based on Coastal Construction Manual and by Federal Emergency Management Agency. In order to examine people's perception toward housing reinforcement as a coping strategy as well as to identify problems and issues associated with achieving stronger and safer housing, focus group and individual interviews were conducted with local residents from four different flood and typhoon-prone communities. The research found that many households in the affected areas now realize the importance of improving housing structures as a coping strategy to resist the impacts of floods and typhoons, however due to low income and a lack of professional instruction and technical guidance in the area, many households still reside in weak and fragile housing conditions that cannot withstand climate related risks. In particular, low-income households spend a considerable amount of their income on housing repair every year. Consultation and communication with professionals about building a resilient housing is lacking. Given that the major immediate recovery action taken by the local people tends to focus on repairing damaged houses, providing proper and applicable construction practices is crucial to improve the housing condition, but also to contribute to reduce poverty in Vietnam.

Coral trace metal of natural and anthropogenic influences in the northern South China Sea

The composition and concentrations of trace metals in coastal seawater have changed in parallel with variations in geochemical processes, climate and anthropogenic activities. To evaluate the response of trace metals in coastal seawater to climatic changes and human disturbances, we report annual-resolution trace element data for a Porites coral core covering ~100years of continuous growth from a fringing reef in Xiaodonghai Bay in the northern South China Sea. The results suggested that the trace metal contents in the coral skeleton demonstrated decadal to interdecadal fluctuations with several large or small peaks in certain years with remarkable environmental significances. All of the trace metals in coastal surface seawater, especially Cr and Pb (related to industrial or traffic emissions), were impacted by terrestrial inputs, except for Sr and U, which were impacted by the surface seawater temperature (SST). Moreover, Mn, Ni, Fe and Co were also contributed by weapons and military supplies during wars, and Cu, Cd and Zn were further impacted by upwelling associated with their biogeochemical cycles. Ba and rare earth element (REE) in coastal surface seawater were dominated by runoff and groundwater discharge associated with precipitation. This study provided the potential for some trace metals (e.g., REE, Ba, Cu, Cd, and Zn) in coral skeletons to be used as proxies of natural (e.g., upwelling and precipitation) and anthropogenic (e.g., war and coastal construction) variability of seawater chemistry to enable the reconstruction of environmental and climatic changes through time.

Understanding the potential risk to marine mammals from collision with tidal turbines

Many marine mammal populations worldwide are in decline due to stresses from climate change and interactions with anthropogenic activities such as fishing, coastal construction petroleum extraction, and commercial shipping. The advent of the marine renewable energy industry has raised questions, particularly for tidal turbines. However, it is technically very difficult to observe close interactions of marine mammals and underwater turbines, and the likelihood of viewing a rare event such as a collision, is very small. This research seeks to understand the potential risk to a marine mammal from the presence of a tidal turbine by examining the sequence of behavioral events that could lead to a potential collision with the turbine, and the likely consequences to the marine mammal if such a collision were to occur. We examine this potential risk within the context of the physical environment into which a turbine might be deployed, and the attributes of one tidal device, and investigate the biomechanical properties of a marine mammal that may allow the animal to resist injury from a tidal blade collision. The data examined in this research (likelihood of a marine mammal being in close proximity to a tidal turbine, biomechanics of marine mammal tissues, and engineering models) provide insight into the interaction.

Surfing Tourism Plan: Madeira Island Case Study

Surfing tourism provides a global business opportunity and forms part of the billionaire industry of adventure tourism. Surfing has successfully attracted participants willing to search for locations and unique adventure experiences, looking for surfing perfect conditions. It becomes essential to understand how surfers list and compare surfing destinations. In Portugal, surfing has been growing exponentially over the last decades not only as a sport, but also as a social and economic activity. However, surf spots have been damaged due to coastal constructions. This study aims to identify characteristics of Madeira´s surf spots and surf industry services. SOS – Salvem o Surf practical model was used, which is based on geography, geology and meteorology aspects, and support infrastructure and services. We also discuss recovering surf spots which lost part of their world class quality, due to not including surfing in coastal management in the past. We consider surf spots improvement for surf tourists and beginners surfers, with the use of Multi-Purpose Reefs. Our results also suggest that surfing provides successfully alternatives, limiting the phenomenon of seasonality. This confirms that Madeira Island possesses several surf spots, with diverse degrees of difficulty, allowing surfing from beginner to advanced levels. This study provides a better understanding of surf tourist’s choice patterns, which benefits both surfers and the tourism industry.

Responses of bottlenose dolphins and harbor porpoises to impact and vibration piling noise during harbor construction

AbstractThe development of risk assessments for the exposure of protected populations to noise from coastal construction is constrained by uncertainty over the nature and extent of marine mammal responses to man‐made noise. Stakeholder concern often focuses on the potential for local displacement caused by impact piling, where piles are hammered into the seabed. To mitigate this threat, use of vibration piling, where piles are shaken into place with a vibratory hammer, is often encouraged due to presumed impact reduction. However, data on comparative responses of cetaceans to these different noise sources are lacking. We studied the responses of bottlenose dolphins and harbor porpoises to both impact and vibration pile driving noise during harbor construction works in northeast Scotland, using passive acoustic monitoring devices to record cetacean activity and noise recorders to measure and predict received noise levels. Local abundance and patterns of occurrence of bottlenose dolphins were also compared with a five‐year baseline. The median peak‐to‐peak source level estimated for impact piling was 240 dB re 1 μPa (single‐pulse sound exposure level [SEL] 198 dB re 1 μPa2 s), and the r.m.s. source level for vibration piling was 192 dB re 1 μPa. Predicted received broadband SEL values 812 m from the piling site were markedly lower due to high propagation loss: 133.4 dB re 1 μPa2 s (impact) and 128.9 dB re 1 μPa2 s (vibration). Bottlenose dolphins and harbor porpoises were not excluded from sites in the vicinity of impact piling or vibration piling; nevertheless, some small effects were detected. Bottlenose dolphins spent a reduced period of time in the vicinity of construction works during both impact and vibration piling. The probability of occurrence of both cetacean species was also slightly less during periods of vibration piling. This work provides developers and managers with the first evidence of the comparative effects of vibration and impact piling on small cetaceans, enabling more informed risk assessments, policy frameworks, and mitigation plans. In particular, our results emphasize the need for better understanding of noise levels and behavioral responses to vibration piling before recommending its use to mitigate impact piling.

Numerical Evaluation of AASHTO Drag Force Coefficients of Water Flow Around Bridge Piers

Drag force is usually exerted on bridge piers due to running river water. This force is calculated empirically based on drag coefficients stated in design codes and specifications. Different values of drag coefficients have been reported in literature. For example, AASHTO LRFD Bridge Design Specifications uses a drag coefficient of 1.4 and 0.7 for square-ended and semicircular-nosed pier, respectively, while Coastal Construction Manual (FEMA P-55) recommends a value of two and 1.2 for square and round piles, respectively. In addition, many researchers have obtained other different values of drag coefficient under similar conditions (i.e., similar range of Reynolds number) reaching to 2.6 for square object. The present study investigates the drag coefficient of flow around square, semicircular-nosed, and 90 deg wedged-nosed and circular piers numerically using finite element method. Results showed that AASHTO values for drag force coefficient varied between very conservative to be under-reckoning. The study recommends that AASHTO drag coefficient values should be revised for different circumstances and under more severe conditions.

Determination of Significant Wave Height Offshore of the Federal Territory of Labuan (Malaysia) Using Generalized Pareto Distribution Method

ABSTRACT Far, S.S.; Wahab, A.K.A., and Harun, S.B., 2018. Determination of significant wave height offshore of the Federal Territory of Labuan (Malaysia) using generalized Pareto distribution method. Probabilistic evaluation of surface waves was undertaken to estimate extreme wave heights for several return periods to use them in coastal and offshore constructions in the Labuan region. Generalized Pareto distribution (GPD), which is the standard practice in mainstream extreme statistics, was developed in MATLAB programming. Several diagnostic plots were drawn to ensure the validity of the GPD model. Extreme wave heights were estimated for several return periods and the confidence intervals band was determined for the estimated extreme wave heights. The wave height data set used in the modeling was observed during a 41-year period from 1949 to 1989, in the South China Sea, inside the offshore area of the Federal Territory of Labuan, off the coast of Sabah, Malaysia. The results highlight the merits associa...

Hurricane damage assessment for residential construction considering the non-stationarity in hurricane intensity and frequency

Natural hazards such as hurricanes may cause extensive economic losses and social disruption for civil structures and infrastructures in coastal areas, implying the importance of understanding the construction performance subjected to hurricanes and assessing the hurricane damages properly. The intensity and frequency of hurricanes have been reported to change with time due to the potential impact of climate change. In this paper, a probability-based model of hurricane damage assessment for coastal constructions is proposed taking into account the non-stationarity in hurricane intensity and frequency. The non-homogeneous Poisson process is employed to model the non-stationarity in hurricane occurrence while the non-stationarity in hurricane intensity is reflected by the time-variant statistical parameters (e.g., mean value and/or standard deviation), with which the mean value and variation of the cumulative hurricane damage are evaluated explicitly. The Miami-Dade County, Florida, USA, is chosen to illustrate the hurricane damage assessment method proposed in this paper. The role of non-stationarity in hurricane intensity and occurrence rate due to climate change in hurricane damage is investigated using some representative changing patterns of hurricane parameters.

Environmental Reviews and Case Studies: Impacts on Maritime Cultural Resources: Assessing the Invisible

The management of developer-led pressures on the marine environment is archaeology's last frontier. Long inaccessible and invisible offshore, advances in technology have today propelled the sunken past into the consciousness of commercial archaeology. Arguably among no other form of heritage assets are archaeology and environment so complexly embedded. Lessons from the recent past have increasingly compelled developers to incorporate surveys of maritime seascapes into environmental impact assessments (coastal construction, sealane deepening, aggregate dredging, wind farms, and oil and gas pipeline and fiber-optic cable laying). Qualitative decisions about what to protect in situ, avoid, or excavate requires an objective understanding of significance assessment in relation to risk. The high profile of the United Nations Organization for Education, Science and Culture (UNESCO) Convention on the Protection of the Underwater Cultural Heritage exerts increasing pressures on governments worldwide to seek sustainable development. Demersal bottom fishing, World War II shipwreck hull oil leakage, and global warming are newly emerged risks that require expanded heritage recognition.

Preliminary Study on the Development of Concrete with Sea Sandas Fine Aggregate

Background/Objectives: In this study, the construction industries expect a serious shortage of sand in the near future due to over exploitation of river sand. This paper deals with the use of sea sand as substitute for conventional river sand. Methods/Statistical Analysis: M20 concrete mix was designed with sea sand as fine aggregate and the workability, strength in compression and split tension and water absorption characteristics are determined and compared with conventional concrete. Findings: The sea sand, as available, is inferior to conventional river sand but proper washing for two times make it feasible for making concrete. For M20 grade concrete, two times washed sea sand can be used as fine aggregate totally replacing river sand as the workability and strength characteristics reach within the limits of acceptable level. Sea sand utilization is cost effective in coastal line construction.

Considering the locals: coastal construction and destruction in times of climate change on Anjouan, Comoros

The current discussion of anticipated climate change impacts and future sea level rise is particularly relevant to small island states. An increase in natural hazards, such as floods and storm waves, is likely to have a devastating impact on small islands' coastlines, severely affecting targeted sustainable development. Coastal erosion, notably human‐induced erosion, has been an ongoing threat to small island biodiversity, resources, infrastructure, and settlements, as well as society at large. In the context of climate change, the problem of coastal erosion and the debate surrounding it is gaining momentum. Before attributing associated impacts to climate change, current human activities need to be analysed, focusing not only on geomorphological and climatological aspects, but also on political and traditional cultural frameworks. The objective of this paper is to demonstrate the importance of the social‐political‐ecological systems analysis for adaptation strategies, and thus for future sustainable development. Coastal use is based on human constructs of the coast, as well as local perceptions and values ascribed to the coast. We use the case study of Anjouan, Comoros to differentiate between constructive and destructive practices on the coast, from both a mental and technical perspective. Beach erosion is described as more than a resource problem that manifests itself locally rather than nationally. Divergent political scales of interest impact future development as much as local action. Local action is not least framed by mental contribution and attribution of coasts as places for living, recreation and resource use. The present case study demonstrates that mental constructs of coasts as valuable areas can, in some cases, lead to the protection and preservation of beaches by initiatives of collective action. At the same time, local communities see the negative impacts of sand mining as causes of coastal erosion and, therefore, it is difficult to mobilize them to adapt to climate change and sea level rise.