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The impact of gold mining activities: understanding the dynamics of cyanide in river ecosystems in Ecuador

Environmental Science and Pollution Research 2024年第56期31卷 64509-64523页

作者： Arellano-Yasaca, Diana Victoria Chu, Chen-Yeon Hoang, Thanh-Van Program for Infrastructure Planning and Engineering Feng Chia University Taichung40724 Taiwan Program for Civil Engineering Water Resources Engineering and Infrastructure Planning Feng Chia University Taichung40724 Taiwan Institute of Green Products Feng Chia University Taichung40724 Taiwan

Understanding the behavior of cyanide in rivers is of utmost importance as it has a direct impact on the health of people who depend on these water sources. Cyanide contamination from gold mining activities poses a significant environmental threat to river ecosystems, particularly in southern Ecuador. This study aimed to investigate the behavior of cyanide when it enters contact with other metals in these rivers. Simulations were conducted to determine the speciation of cyanide, mercury, arsenic, lead, and manganese in a study area, taking into account the water temperature and pH at four locations. The findings revealed that CN−and HCN(aq) species were present in the research area. Additionally, mercury-cyanide (Hg(CN)2(aq), Hg(CN)3−), and manganese-cyanide (MnCN+) complexes were identified 3 km downriver from the site where the mining activity is higher. These metal-cyanide complexes tend to dissociate quickly under weak acidic conditions, making them hazardous to the environment. This research is crucial, not only for the environment but also for human health, as it allows to predict toxicity risks for people supplied with this water source, emphasizing the potential harm to human health. This study highlights the importance of stringent regulations and effective monitoring practices to mitigate cyanide contamination and safeguard environmental and occupational health. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.

关键词： River pollution

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NUMERICAL ANALYSIS OF SHAPE AND DEPTH FACTORS OF PERFECTLY ROUGH OR SMOOTH SHALLOW FOOTINGS ON AN INHOMOGENEOUS SINGLE LAYER OR INTERFACE OF TWO-LAYERED COHESIVE SOILS

Journal of GeoEngineering

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Journal of Geoengineering 2023年第2期18卷 59-69页

作者： Chi, Chao-Ming Lin, Zheng-Shan Department of Civil Engineering Feng Chia University Xitun Dist Taichung Taiwan Program for Infrastructure Planning and Engineering Feng Chia University Xitun Dist Taichung Taiwan

This study utilizes an explicit finite difference program to investigate the effect of circular shape, embedment depth, and footing roughness to the bearing capacity of large shallow foundations placed on an inhomogeneous cohesive single layer soil deposit or set on the interface of a two-layered cohesive soil system. Because the dimensions of offshore foundations are in general larger than those of onshore footings, the inhomogeneous and layered soil effect to the bearing capacity would be more significant. Moreover, many large foundations are usually circular metal footings, such as spudcan footings of jack-up barges, so the considerations of shape and roughness effect are necessary. In this study, the soil is modelled by a perfectly plastic material with Tresca yield criterion and the associated flow rule. When a kinematically admissible velocity field which satisfies the constraints imposed by compatibility, velocity boundary and the flow rule is determined, the numerically collapse load can be obtained. The results from numerical simulations indicate that the bearing capacity is associated with the pattern of soil plastic flow and affected by the foundation shape, footing roughness, embedment ratio, soil strength ratio, and inhomogeneity factor. According to the numerical simulation results, several regression equations are recommended for the circular shape factor and depth factor with footing roughness consideration, so engineers can utilize those to fast calculate the bearing capacity of a footing on an inhomogeneous single layer soil deposit or a two-layered cohesive soil system. The results also indicate that even though the embedment depth benefits the bearing capacity, the effectiveness of stronger top soil layer is more significant because the associated soil plastic flow range enlarges. © 2023, Journal of Geoengineering. All Rights Reserved.

关键词： Soils

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Streets, density, and the superblock: neighborhood planning units and street connectivity in Abu Dhabi

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Journal of Urbanism 2023年第2期16卷 168-195页

作者： Alawadi, Khaled Hong Nguyen, Ngoc Alrubaei, Eiman Scoppa, Martin Department of Civil Infrastructure and Environmental Engineering Sustainable Critical Infrastructure Program Khalifa University Abu Dhabi United Arab Emirates Faculty of Architecture The University of Danang-University of Science and Technology Danang Viet Nam Sustainable Critical Infrastructure Program Department of Civil Infrastructure and Environmental Engineering Khalifa University Abu Dhabi United Arab Emirates Architecture Engineering Department College of Engineering United Arab Emirates University Alain United Arab Emirates

This article studies the efficiency of street networks of Neighborhood Planning Units. Pedestrian Route Directness quantified the NPUs’ efficiency. The sample includes ten Abu Dhabi NPUs built during two periods: pre-1990 and post-1990. Two scenarios are assessed. First, as-built streets are evaluated based on the PRD test. Second, PRD values of NPUs with different plot densities are compared. Results show that plot density does not affect efficiency. A good network design produces high efficiency regardless of its plot density. The effects of streets on efficiency were further revealed by Betweenness. Combining PRD and Betweenness yields important principles of network design. This method can be applied to assess the connectivity of streets in different contexts. Future research should focus on: How do alleys contribute to the efficiency of NPUs? How do street configurations influence the behavior of movement? And how should NPUs be evaluated as local street systems with global implications?. © 2021 Informa UK Limited, trading as Taylor & Francis Group.

关键词： betweenness density neighborhood planning units pedestrian route directness Street connectivity

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Mechanical Performance Improvement by Carbon Dioxide Curing of Cement Concrete Incorporating Oil Shale Residue 1st

Mechanical Performance Improvement by Carbon Dioxide Curing ...

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1st International Conference on Emerging Smart Cities, ICESC 2022

作者： Syuhada, Syahidus Al Salaheen, Marsail Alaloul, Wesam Salah Alzubi, Khalid Mhmoud Civil Engineering Study Program Department of Infrastructure Technology and Planning Institut Teknologi Sumatera Sumatera Indonesia Department of Civil and Environmental Engineering Universiti Teknologi PETRONAS Seri Iskandar Malaysia Department of Civil and Environmental Engineering Al-Husun University College Irbid Jordan

ISBN: (纸本)9789819911103

The influence of carbon dioxide (CO2) curing on the compressive strength of oil shale ash (OSA) concrete as partial cement replacement was investigated. 15 cm cubes with a 30% replacement percentage were tested after seven days of conventional curing and carbonation curing at 4 bar CO2 pressure. Research results demonstrate that CO2 curing influences the compressive strength of concrete significantly. There is a linear relationship between CO2 pressure and the duration of curing, as well as the compressive strength of OSA-based concrete. A sample of ordinary Portland cement was used as the control sample. The replacement of 30% cement by OSA increased the 7-day compressive strength from 48.5 to 55.5 MPa for plain cement samples and from 36.5 to 42.3 MPa for ash-based samples. From a technical standpoint, OSA-based concrete carbonation curing is still too immature for widespread application. Nonetheless, it is continuously developing in response to greenhouse gas reduction and paving the path for a more sustainable construction materials business. © 2024, Institute of Technology PETRONAS Sdn Bhd.

关键词： Carbon dioxide

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Bearing Capacity Factor Characteristics of Footings on Double-layered Cohesive Soils

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Journal of Marine Science and Technology (Taiwan) 2023年第4期31卷 403-419页

作者： Chi, Chao-Ming Lin, Zheng-Shan Kuo, Yu-Shu Dept. of Civil Engineering Feng Chia University Taichung407802 Taiwan Program for Infrastructure Planning and Engineering Feng Chia University Taichung407 Taiwan Dept. of Hydraulic and Ocean Engineering National Cheng Kung University Tainan701 Taiwan

In this study, the bearing capacity of a surface foundation resting on a double-layered cohesive soil profile was investigated by applying a rotational mechanism and finite-difference numerical simulations. The bearing capacity factor behaviors of a surface footing on double-layered cohesive soils can be classified and illustrated using a characteristic chart. Depending on the soil strata strength ratio and normalized layer thickness, the soil-foundation system can be in the squeezing, factor-increasing, factor-decreasing, or constant factor zones. The results indicated that the trend of the curves in the characteristic chart computed from the asymmetric failure mechanism was in accordance with that of the symmetric failure mechanism of the numerical simulation. Based on the strength conditions of the upper and lower soil layers, the soil plastic flow zone may enlarge, shrink, or even become constrained. For the analysis of the critical soil strength ratio that causes punching shear failure, the results from the SNAME method were less conservative. Moreover, the footing roughness effect was significant in the weaker upper soil case and may have contributed to a 25 % higher bearing capacity. © 2023 National Taiwan Ocean University.

关键词： Digital elevation model

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Navigating Legal Frameworks for National Resilience: A Comparative Analysis of Key Disaster Management Laws in Thailand and Japan 4

Navigating Legal Frameworks for National Resilience: A Compa...

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4th International Symposium on Instrumentation, Control, Artificial Intelligence, and Robotics, ICA-SYMP 2025

作者： Laosunthara, Ampan Thongthip, Ratchaneekorn Krutphong, Kodchakorn School of Environment and Society Institute of Science Tokyo Tokyo Japan Disaster Preparedness Mitigation and Management Department of Civil & Infrastructure Engineering Pathumthani Thailand Environmental Engineering and Disaster Management Program Mahidol University Kanchanaburi Thailand

ISBN: (纸本)9798331505400

This study compares the disaster management laws of Thailand and Japan. The research reveals significant differences in legislative approaches, reflecting each country's unique historical, and governance contexts. Japan's law demonstrates a more comprehensive approach to the disaster management cycle and stakeholder involvement, with integrated financial provisions. Thailand's law emphasizes organizational aspects. Both prioritize response measures but show potential gaps in addressing preparedness and mitigation phases. The study identifies areas for further investigation, including financial measures, and international cooperation approaches. This comparative analysis offers valuable insights into both countries' ongoing development of disaster management systems and highlights potential areas for mutual learning and improvement in disaster risk reduction strategies. Creating resilience in the society through the core of the government working and stakeholders' given authorities. © 2025 IEEE.

关键词： Disaster prevention

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Controlled diesel-mixed soils for roadway embankments: laboratory and ultrasonic characterization

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Arabian Journal of Geosciences 2023年第5期16卷 1-12页

作者： AbdelSalam, Sherif S. Hasan, Ahmed M. M. Civil and Infrastructure Engineering and Management Program School of Engineering and Applied Science Nile University Giza Egypt

Soils contaminated with hydrocarbons is a repetitive site condition that may occur at locations adjacent to underground fuel tanks and other facilities. The main purpose of this study is to characterize and assess possibilities of reusing contaminated soil in useful applications such as roadway embankments. Accordingly, controlled amounts of diesel were mixed with clays and sands using percentages ranging from 0 to 13.5%. Unconfined compression, direct shear, California bearing ratio, and other tests were conducted on the diesel-mixed soil, along with the ultrasonic test. The ultrasonic test provided measures for the pulse wave velocity and received frequency, which was correlated with other soil parameters such as elastic modulus, resilient modulus, and California bearing ratio. From the main outcomes, it was found that small amounts of diesel can help improved soil shear strength. For instance, adding 5% diesel increased the soil cohesion by 63% and the unconfined compressive strength from 0.14 to 0.21 N/mm2. In sands, the California bearing ratio increased by almost double by adding 5% diesel, which is essential for roadway embankments especially in remote locations. Damping coefficient of soil was determined at different levels of diesel using the ultrasonic wave decay envelops. The ultrasonic waves were analyzed using fast Fourier transform to determine useful correlations between the wave frequency and the diesel content starting from 0 to 13.5%, and it was realized that an uncomplicated ultrasonic test can be acceptably used to assess static and dynamic properties of clean as well as contaminated soils.

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Fiber reinforced polymers for historical bridges upgrading: a fatigue life assessment

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Journal of Building Pathology and Rehabilitation 2023年第1期8卷 1-11页

作者： Garcez, Mônica Regina Meneghetti, Leila Cristina Post-Graduate Program in Civil Engineering: Construction and Infrastructure Federal University of Rio Grande do Sul Porto Alegre Brazil Department of Structural and Geotechnical Engineering University of São Paulo São Paulo Brazil

Upgrading historical structures is one of the most interesting applications of fiber reinforced polymers in construction. Historical bridges are frequently post-strengthened to increase load carrying capacity of structural elements, aiming to bear heavier commercial traffic. Fatigue life becomes crucial since the lack of available fatigue models leads to superficial analysis considering the same S–N curves for different strengthening systems and steel stress ranges. This paper uses an extensive database with experimental data from the literature to adjust linear regression models to characterize the large scatter between the results of fatigue tests from different sources. Distinct fatigue models have been developed considering three categories: externally bonded reinforcement with strips/sheets and new surface-mounted reinforcement. The different declivities found for the adjusted fatigue life models accurately represent the fatigue behavior of the post-strengthened structural elements with the assessed systems and techniques. The results support design decisions to avoid future unnecessary interventions. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Fatigue life Fiber reinforced polymers Historical bridges Linear regression analysis

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Flood Management Strategies in Indonesia: A Lesson Learned from Pepe River, Central Java 5th

Flood Management Strategies in Indonesia: A Lesson Learned f...

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5th International Conference on Rehabilitation and Maintenance in civil engineering, ICRMCE 2021

作者： Prastica, Rian Mantasa Salve Wijayanti, Amalia Civil Engineering Department Gadjah Mada University Yogyakarta55281 Indonesia Water Infrastructure Construction Technology Study Program Public Works Polytechnic Semarang50275 Indonesia

ISBN: (纸本)9789811693472

Floods occur every year and threaten communities worldwide. Indonesia is among the countries faced with this problem and still struggling to seek practical solutions to date. Further, as the country’s centers of trade, business, and technology, the island of Java cannot even perform better in dealing with floods. To further understand possible damage and losses, this research investigated structural mitigation measures as part of flood management in the Pepe River, notably river channelization to increase hydraulic efficiency. For the analysis, it used HEC-RAS to observe the river capacity. Existing conditions revealed that the river could not accommodate the predicted floods based on the return periods derived from the synthetic unit hydrograph of Nakayasu. However, after running the mitigation scenario wherein hydraulic modification was applied, flood risk could be reduced by lowering the river water level. Based on the results, it can be concluded that Indonesia needs to pay more attention to other aspects: ecology, green infrastructure, and water governance, to achieve more effective flood mitigation measures because structural mitigation only provides a temporary solution. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Rivers

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Structural performance of reinforced concrete beams subjected to combined effects of corrosion and cyclic loading

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Journal of Building Pathology and Rehabilitation 2023年第1期8卷 1-10页

作者： Stein, Kássio Joe Graeff, Ângela Gaio Garcez, Mônica Regina Civil Engineering Post-Graduation Program: Construction and Infrastructure Federal University of Rio Grande do Sul Av. Osvaldo Aranha 99 7th floor room 706 RS Porto Alegre 90035-190 Brazil

The deleterious effects of steel rebar corrosion in bridges and viaducts can be potentialized by the cyclic loading to which such structures are naturally exposed. While cyclic loading may lead to progressive bond deterioration and concrete cover cracking, corroded steel rebars may accelerate the fatigue damage accumulation in reinforced concrete elements. Thus, the combined effects of corrosion and fatigue are still more damaging than the disassociated degradation processes. Under this perspective, the experimental program presented in this paper evaluates the synergy between corrosion and fatigue through the load-bearing capacity, vertical displacements at midspan, failure mode, cracking, and fatigue life of corroded reinforced concrete beams submitted to cyclic loading. Corroded reinforced concrete beams (120 × 200 × 1500mm, 2φ12.5 mm, φ 6.3 mm each 100 mm at midspan and 60 mm at shear span) were submitted to 2 million loading cycles (5 Hz) and tested up to failure under a four-point bending scheme. The steel rebar corrosion was accelerated by immersion corrosion testing up to 3–5% (low level) and 8–11% (high level) mass loss. The isolated effects of fatigue and low-level corrosion (3–5%) did not influence the load-bearing capacity and ductility of the reinforced concrete beams, unlike beams submitted to high corrosion levels. The fatigue loading did not influence the load-bearing capacity and ductility of the reinforced concrete beams submitted to low corrosion levels but increased the crack opening, reduced the ultimate load by about 10%, and reduced the ductility of the beams submitted to high corrosion levels. The failure mode changed from ductile to brittle in reinforced concrete beams submitted to high corrosion levels. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Corrosion Cyclic loading Fatigue Reinforced concrete Structural performance

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