Search Results (20)

Geotextile bags are widely used in revetment engineering due to their simple fabrication and cost-effectiveness. However, prolonged exposure to natural environments can lead to aging and damage, compromising their performance. To enhance the durability of geotextile bags in practical applications, this study conducted microscopic examinations and strength tests, employing a slurry spraying method to form a protective surface layer. Adhesion tests and orthogonal experiments were performed to evaluate the impact of spraying parameters on performance. The optimal parameter combination was determined through range analysis, variance analysis, and projection pursuit regression (PPR) analysis, with the durability improvement verified by accelerated aging tests. Results demonstrated that sediment significantly reinforced the internal fibers and mechanical properties of the geotextile. Artificial slurry spraying effectively adhered to the geotextile surface, with clay slurry exhibiting the strongest adhesion. By integrating range analysis, variance analysis, and PPR analysis, the key influencing factors were identified as spraying thickness, geotextile thickness, and clay content. The optimal parameter combination was selected for accelerated aging tests and electron microscopy observation, revealing that the spraying treatment significantly improved the geotextile’s strength retention rate, delayed performance degradation under UV and high-temperature conditions, and protected the fiber structure. These findings provide valuable insights in terms of enhancing the durability of geotextile bags. Full article

Coastal erosion is a critical environmental challenge in the Upper Gulf of Thailand, driven by both natural processes and human activities. This study analyzes 35 years (1988–2023) of shoreline changes using geoinformatics, machine learning algorithms (Random Forest, Support Vector Machine, Maximum Likelihood, Minimum Distance), and the Digital Shoreline Analysis System (DSAS). The results show that the Random Forest algorithm, utilizing spectral bands and indices (NDVI, NDWI, MNDWI, SAVI), achieved the highest classification accuracy (98.17%) and a Kappa coefficient of 0.9432, enabling reliable delineation of land and water boundaries. The extracted annual shorelines were validated with high accuracy, yielding RMSE values of 13.59 m (2018) and 8.90 m (2023). The DSAS analysis identified significant spatial and temporal variations in shoreline erosion and accretion. Between 1988 and 2006, the most intense erosion occurred in regions 4 and 5, influenced by sea-level rise, strong monsoonal currents, and human activities. However, from 2006 to 2018, erosion rates declined significantly, attributed to coastal protection structures and mangrove restoration. The period 2018–2023 exhibited a combination of erosion and accretion, reflecting dynamic sediment transport processes and the impact of coastal management measures. Over time, erosion rates declined due to the implementation of protective structures (e.g., bamboo fences, rock revetments) and the natural expansion of mangrove forests. However, localized erosion remains persistent in low-lying, vulnerable areas, exacerbated by tidal forces, rising sea levels, and seasonal monsoons. Anthropogenic activities, including urban development, mangrove deforestation, and aquaculture expansion, continue to destabilize shorelines. The findings underscore the importance of sustainable coastal management strategies, such as mangrove restoration, soft engineering coastal protection, and integrated land-use planning. This study demonstrates the effectiveness of combining machine learning and geoinformatics for shoreline monitoring and provides valuable insights for coastal erosion mitigation and enhancing coastal resilience in the Upper Gulf of Thailand. Full article

Pre-tensioned H-type prestressed concrete revetment piles are a newly developed product dedicated to the protection of river, lake, and sea bank embankments, and their cross-section is H-shaped. In this study, a field test of H-type pile soil’s squeezing effect is carried out based on the second phase project of the HujiaShen Line. Pore water pressure, soil displacement, and other parameters of the H-type pile-driving process are monitored in real time. The test results show the following: (1) The influence range of the excess pore water pressure caused by the soil squeezing effect in the horizontal direction is about 14–15D, and in the vertical direction, the pore water pressure within a depth range of about 7D below the pile bottom increases rapidly. Its dissipation rate is fast at first and then slows down, and it completely dissipates 20 days after piling. (2) The excess pore water pressure caused by the soil squeezing effect does not decrease linearly in the radial direction. The soil around the construction pile can be divided into four areas: A, B, C, and D. Among them, A and B belong to the plastic zone, and C and D belong to the elastic zone. (3) The horizontal displacement of the soil occurs within the depth range of 5D from the surface of the pile to the bottom of the pile at the piling location, and the radial influence range is about 8–12D. From a vertical perspective, the main horizontal displacement of the soil occurs in the long section of the pile driven into the soil, showing a “U”-shaped distribution. (4) The dividing point between the vertical displacement uplift and the settlement of the soil appears within the range of 2–3 m from the construction pile, that is, between 5 and 7D. Settlement occurs after the piling is completed, and the settlement rate is fast at first and then slows down. The final settlement of the soil is stable on the 20th day. This research and experiment provide a design reference for the engineering application of pre-tensioned H-type prestressed concrete bank protection piles. Full article

Amidst the backdrop of growing great power competition, heightened United States presence via military bases has manifested in the Arctic. However, the then design and implementation have hampered the resilience of these bases in a region warming at nearly four times the rate of the rest of the globe. Two-thirds of the United States’ 79 military bases in the Arctic remain underprepared against permafrost thaw and rising sea levels despite rampant calls for sustainable strategies. Damages emanating from climate-related failures will continue to cost the U.S. billions of dollars and render crucial infrastructure unusable. The objective of this study is to present a comprehensive literature review of the extent of Arctic warming and its significance for U.S. bases, the negative implications of military infrastructure deterioration, and methods to adapt both existing and forthcoming bases to a rapidly warming atmosphere. Eighty published papers that directly or indirectly referenced U.S. military bases or climate-oriented engineering in the aforementioned contexts were identified and analyzed over a 20-year period from 2004 to 2024. The literature review concludes that warming concerns were often not taken into much account by civil engineers during initial base construction, an oversight that now jeopardizes runways, docks, and highways. Other nations that have a sizeable footprint in the Arctic Circle, such as Canada and Russia, have demonstrated progress by utilizing pile-driven substructures, thawing permafrost before construction, and ventilated crawlspaces. Alternative solutions, such as cooling permafrost via thermosiphons or refrigeration systems, employing spatially oriented foundations composed of specific materials, and preventative measures such as floodwalls and revetments, have also shown considerable promise in simulations and practice. A table illustrating a holistic literature summary of sustainable strategies to current conditions and climate change at U.S. Military Bases in the Arctic region is also developed. Modeling successful engineering concepts and incorporating existing innovations into military infrastructure should be at the forefront of the United States’ sustainable policy. Full article

With emphasis on constructing low-carbon cities, the renovation of the riverbank highlights energy conservation and carbon reduction. However, methods and standards for quantifying carbon emissions during ecological river channel construction are currently lacking. There is a scientific gap in research into carbon footprint assessment and reduction potential in ecological revetment technologies in water networks of China. This study attempts to clarify the carbon emission factors of different ecological revetment technologies and explore the carbon reduction potential during the construction stage of ecological rivers from the river revetment design, construction process and materials. The results show that in the carbon emission factors of six ecological revetment technologies, building materials have the largest adjusting potential for carbon reduction. The concrete material is responsible for 55.37–95.86% of carbon emissions in six ecological river technologies, with an average proportion of 69.96%. Accordingly, the concrete material emerges as the primary contributor to carbon emissions in ecological river engineering, followed by gasoline truck transportation and earthwork excavation. Moreover, the carbon emissions from ecological frame structures were the largest, followed by those of block structures, gabion structures, planted concrete and interlocking blocks and the wooden stake structure has the smallest carbon footprint. The choice of ecological revetment technologies is not only related to the realisation of regional water conservancy functions, but it also affects the carbon emissions of water conservancy projects. Engineers and decision-makers should pay great attention to the optimal design of the project, selection of low-carbon materials, energy saving and emission reduction in the construction process. This research not only provides guidance for design units in selecting appropriate river revetment technologies but also offers a theoretical foundation and data support for construction units to optimise their construction process management. Full article

Coastal dikes have been built for millennia to protect inhabited lands from exceptional high tides and storm events. Currently, many European countries are developing specific programs to integrate the construction of new dikes (or the raising of existing ones) into the built environment to face sea level rising. Technical difficulties in succeeding in this operation are questioning the paradigm of protection for the long term, pointing out the need for alternative strategies of adaptation that are not yet fully explored. This paper elaborates on innovative models to deal with coastal flooding, presenting the results of an interdisciplinary research and design process for the case-study of Southend-on-Sea (UK). Detailed numerical simulations are used to develop a spatial strategy to accommodate water during extreme events, introducing different prototypes of dike designs that include seawalls, enhanced roughness through rock and stepped revetments, as well as vegetation. The overall goal is to push forward the traditional approach of planning water protection infrastructure within the solely field of civil engineering. It elaborates on the integration of the disciplines of spatial design and engineering and presents novel advances in terms of spatial design for the revetment of overtopping dikes. Full article

Precast concrete block slope protection is widely used due to its advantages of easy detection and laying, ease of organization, and the limited time required for construction. In order to prevent the soil or gravel bedding of precast concrete from being subjected to wind and wave pressures, the joints between precast concrete blocks are usually filled with mortar. However, the existing standards do not specify the width or material of the joints. Furthermore, excessively wide mortar joints or shrinkage of the mortar can result in loss, a hollowed-out cushion, and damage to the slope, thus compromising the quality of slope protection engineering. To establish standards for controlling the quality of slope protection seams, this paper designed and conducted a physical model test of precast concrete block revetment seams. By embedding pore water pressure sensors in the cushion layer, changes in the pore water pressure were observed under varying conditions, including different water pore pressure sensor locations, water levels in front of the embankment, and different joint widths. Based on the test results, design standards for joint widths and recommendations for the treatment of joint mortar materials were proposed. After adding different amounts of a calcium oxide–calcium sulfoaluminate composite expansion agent (HME) into a joint mortar material, the paper also carried out a shear test on the contact surface between the joint mortar and the slope protection concrete after adding varying amounts of a calcium oxide-calcium sulfoaluminate composite expansion agent (HME) to the joint mortar material. Following a microporous structure test, recommendations for joint mortar construction treatment were proposed. The results indicate that the pore water pressure of the precast concrete slope protection cushion is closely related to the position of the cushion, the water level in front of the embankment, and the width of the paving seam. When the masonry seam width increased from 0.5 mm to 1 mm and from 1 mm to 1.5 mm, the variation ranges of the pore water pressure were 40–80% and 6–20%, respectively, with the latter being significantly lower than the former. Therefore, in practical engineering, joint treatment should take into account the impact of the cushion position, the water level in front of the dike, and the joint mortar width. Mortar shedding within the range of wave climbing height should be addressed promptly, and joint width should be controlled to below 1 cm as much as possible to effectively prevent damage to the cushion surface. The addition of an expansion agent can improve the bond strength of the concrete and mortar to a certain extent. The study found that an 8% content of the expansion agent resulted in the best mortar bond strength and the densest microstructure. These research findings can serve as a basis for the development of quality control standards for precast concrete slope protection. Full article

There are currently at least five aircraft runways built on the reclaimed coral sand foundations in the South China Sea (SCS). The seismic dynamics and stability of the revetment breakwaters and nearby aircraft runways built on reclaimed lands with coral sand in the SCS deserve attention. Taking the reclamation engineering in the SCS as the background, this study performed several centrifuge shaking table tests (N = 50 g) to explore the seismic dynamics and stability of a revetment breakwater and a nearby aircraft runway built on a reclaimed coral sand foundation. It is revealed that the revetment breakwater, aircraft runway, and their coral sand foundation have intensively responded to the excitation of seismic waves. The pore water pressure accumulates in the coral sand foundation; however, the accumulation amplitude is not significant. As a result, only soil softening, rather than liquefaction, has occurred in the coral sand foundation. The final residual subsidence of the revetment breakwater and aircraft runways are both about 0.5 mm, indicating that they are finally in a stable state. Through comparative study, it is found that the pore water pressure in the loose coral sand foundation is much easier to accumulate, and the corresponding acceleration amplification effect is also more significant. It means that a loose coral sand foundation is more detrimental to the seismic stability of the revetment breakwaters and airport runways. Full article

Aimed at improving the production efficiency of tetrahedron-like pervious frames for the river revetment, self-compacting steel fiber reinforced concrete (SFRC) was applied to strengthen the tensile resistance of concrete to remove conventional steel bars used as reinforcement. The workability and mechanical properties of self-compacting SFRC were experimentally studied with the volume fraction of steel fiber changed from 0.4% to 1.2%, and the rational volume fraction of 0.8% was determined for producing the pervious frames. Based on the flow-induced orientation of the steel fibers in the fresh mix, the casting process of self-compacting SFRC was optimal from one inclined rod to other two inclined rods and the horizontal rods of the pervious frame. The loading capacities of pervious frames during lifting and stacking were respectively detected by the simulation tests on the testing machine, which ensure the safety of pervious frames lifted six layers together and stacked for nineteen layers. By testing groups of pervious frames throwed in and then salvaged from the river, the quality of pervious frames without any damage was observed. Finally, the pervious frames were successfully applied in an engineering project for the river revetment. Full article

Still-water ponds in urban parks are often eutrophic; hence, these ponds are typically at risk of algal blooms, which have a negative impact on landscapes and visitor experiences. Instead of adopting the current mainstream methods of ex situ ecological remediation with flowing water bodies, such as the construction of a circulating filtration system or an artificial wetland system around the pond, this research adopted in situ ecological remediation in still-water ponds to suppress algal blooms. The plan was implemented through a small-scale engineering design and plant configuration inside the pond. Using six still-water ponds in Beijing Yu Park as experimental sites, different mini-engineering designs and plant configurations were implemented at different ponds to perform comparative experiments, and the water quality of each pond was monitored for three consecutive years. By summarizing the variation in key water quality indices for each pond, we found that a mini-engineering design of “multilevel” pond revetments and lakebeds combined with a “multilayer” aquatic macrophyte configuration of floating-leaved plants, emergent plants, and submerged plants could effectively inhibit algal blooms. Thus, an effective ecological self-purification model and corresponding landscape design principles for still-water ponds in urban parks were proposed. Full article

The development of coastal regions combined with rising sea levels is leading to an increasing risk of coastal flooding caused by wave overtopping of natural beaches and engineered coastal structures. Previous measurements of wave overtopping have been obtained for static coastal structures using fixed current meters and depth sensors or tanks. These are unsuitable for dynamically stable coastal protection structures however, because the geometry of these structures is expected to evolve under wave action. This study investigates the potential to use elevated 2D laser scanners (Lidar) to remotely sense the flow volumes overtopping the time-varying crest of a porous dynamic cobble berm revetment. Two different analysis methods were used to estimate the wave-by-wave overtopping volumes from measurements of the time-varying free surface elevation with good agreement. The results suggest that the commonly used EurOtop parameterisation can be used to estimate overtopping discharge to an acceptable precision. An advantage of the remote sensing approach reported here is that it enables the spatial distribution of overtopping discharge and infiltration rate to be measured. It was found that the overtopping discharge on a porous dynamic revetment decays rapidly landward of the structure crest, and that this has implications for safety and structure design. Full article

The present paper addresses the litho-dynamic and morpho-dynamic processes in the coastal zone of Babie Doły (KM 93.6–93.9), Poland. As a background, the history of coastal engineering measures in this area is described. The impact of post-war structures on the seashore is analysed on the basis of historical maps, supported by results of the sediment transport modelling. Shore regression is caused by the so-called downstream erosion behind the headland with remains of rock palisade structures. The possible consequences for the seashore resulting from the removal of the analysed revetment are discussed. The paper also presents recommendations to the relevant authorities for the future. Full article

This study uses the cognitive factor of “visual harmony” to assess the visual quality of stream engineering in a mountainous region. Images of engineering structures such as revetments and submerged dams in the mountain streams of Taiwan were collected. Three image groups with different structures invaded by vegetation were used for a questionnaire survey, which yielded 154 valid samples. We used statistical analysis to develop a model of visual harmony H with respect to the percentage of visible greenery G_R, that is, the perceived curve of vegetation change. A comparison of our data with the literature determined the upper and lower bound curves of the relationship between H and G_R. We found that the physical elements of “softscape” and “hardscape”—namely, percentage of visible water W_R, visible structure I_R, and visible natural material on the structure N_R—affected this relationship. Results show that H is equivalent to visual preference P, and both can be improved by better green visibility (increasing G_R and G_R < 50%), avoiding low water visibility (W_R < 10%), or increasing the amount of visible natural material (N_R > 0.9). High visibility of the structures (I_R > 0.3) may decrease H and P. We ultimately propose a visual harmony or preference model concerning a combined physical indicator that comprises G_R, W_R, I_R and N_R. Results of this study could be helpful to improve or access the aesthetics of stream engineering design. Full article

In the past several years, a series of artificial islands have been constructed on the top of coral reefs by China in the South China Sea by way of reclamation. A large number of revetment breakwater also has been built along the margin of these artificial islands. The stability of these revetment breakwater is the precondition for the normal service performance of these reclaimed coral sand islands. In this study, taking the reclamation engineering in the South China Sea as the background, a series of wave flume physical model tests (geometrical similarity scale is set to 1:10) are performed to investigate the dynamics and the stability of the revetment breakwater and its reclaimed coral sand foundation under the impact of regular wave. Experimental results show that the revetment breakwater has a maximum final settlement of 6 mm if built on loose coral sand foundation. Furthermore, there is indeed excess pore pressure generated in the reclaimed coral foundation with a maximum magnitude of 1.5 kPa. It is found that the excess pore pressure has not caused liquefaction in the coral sand foundation due to the fact that the accumulation of excess pore pressure only occurred in the first 10 cycles of wave loading. Finally, it is concluded that the revetment breakwater and its reclaimed coral sand foundation basically are stable under regular wave impacting. However, excessive water overtopping would be a potential threat for the vegetation behind the breakwater, as well as for the desalinated underground water of the reclaimed lands. Full article

Recently, the coastal zone in Vietnam has experienced more intensive sea attacks due to severe typhoons, climate change, and humsection an activities. Sea level rise has been recorded all along the coast. Moreover, sand exploitation and engineering measures have significantly changed local reliefs and led to apparent sea water level change on the coast of Nam Dinh province. Coastal erosion and sea dike failures have become a serious problem in the region. The site investigation of nearshore topography shows the recent changes to the coast. Hydrodynamic models show that changes of relief and increased wave attacks on dikes. The main reason for sea dike instability is soil erosion due to wave topping; meanwhile, the dikes are stable in terms of sliding. The coast should be reinforced with properly constructed revetments, wave topping preventive measures, and nearshore sand exploitation should be halted. Full article