Search Results (9)

High-speed railways are critical infrastructure in many countries, but their construction generates substantial spoil, particularly in mountainous regions dominated by tunnels and slopes, necessitating the establishment and monitoring of spoil disposal areas. Inadequate monitoring of spoil disposal areas can lead to significant environmental issues, including soil erosion and geological hazards such as landslides and debris flows, while also hindering the recycling and reuse of construction spoil, thereby impeding the achievement of circular economy and sustainable development goals for high-speed railways. Although the potential of geographic information systems, remote sensing, and global positioning systems in waste monitoring is increasingly recognized, there remains a critical research gap in their application to spoil disposal areas monitoring within high-speed railway projects. This study proposes an innovative framework integrating geographic information systems, remote sensing, and global positioning systems for monitoring spoil disposal areas during high-speed railway construction across three key scenarios: identification of disturbance boundaries (scenario 1), extraction of soil and water conservation measures (scenario 2), and estimation of spoil volume changes (scenario 3). In scenario 1, disturbance boundaries were identified using Gaofen-1 satellite data through processes such as imagery fusion, unsupervised classification, and spatial analysis. In scenario 2, unmanned aerial vehicle data were employed to extract soil and water conservation measures via visual interpretation and overlay analysis. In scenario 3, Sentinel-1 data were used to analyze elevation changes through the differential interferometric synthetic aperture radar method, followed by the estimation of spoil volume changes. The effectiveness of this integrated framework was validated through a case study. The results demonstrate that the framework can accurately delineate disturbance boundaries, efficiently extract soil and water conservation measures, and estimate dynamic changes in spoil volume with an acceptable error margin (15.5%). These findings highlight the framework’s capability to enhance monitoring accuracy and efficiency. By integrating multi-source data, this framework provides robust support for sustainable resource management, reduces the environmental impact, and advances circular economy practices. This study contributes to the efficient utilization of construction spoil and the sustainable development of high-speed railway projects. Full article

To enhance the adhesion between tuff and asphalt, this study investigates the efficacy of alkalinization treatment technology using a molecular self-assembly layer derived from the silane-coupling agent γ-aminopropyltriethoxysilane (APTES). APTES hydrolysis solutions at varying concentrations were prepared to assess their impact on the adhesive strength of the aggregate–asphalt interface and water damage resistance. Using surface energy theory, the interface adhesion work of tuff was analyzed, while SEM and EDS were employed to examine changes in surface morphology and composition after treatment. The results demonstrate that an APTES:water:ethanol mass ratio of 5:45:50, along with a curing temperature of 200 °C, significantly improves the bonding strength between tuff and asphalt. The silanol groups on APTES react with hydroxyl groups on the tuff surface to form siloxane bonds (Si-O-Si), anchoring APTES to the tuff. This study elucidates the self-assembly mechanisms of APTES on tuff aggregates and demonstrates the consequent enhancement of interfacial adhesion, providing valuable insights for the application of tuff as tunnel spoil in road engineering. Full article

A majority of metro projects have been constructed to reduce urban traffic congestion and to improve the convenience of public transportation, but these projects also produced a significant amount of engineering slag and mud. The shield construction method could improve the efficiency and safety; this technique has been frequently used in tunnel excavation projects. However, the spoil produced during the shield construction is challenging to deal with. In literature, though there has been an increasing number of studies on the technologies of utilizing shield spoil, the on-site utilization of shield spoil is still a subject of little research. This study introduced an implementation framework for the on-site utilization of shield spoil based on successful case experiences. It aims to assist project managers in efficiently implementing on-site resource utilization projects and to address the gaps in the relevant field. A case study was conducted in the Shenzhen Metro Line 13 North Extension Project; this study collected data through six semi-structured interviews and field research, analyzed the data, and constructed a framework using thematic analysis and focus group discussions. The three components of the implementation framework are project planning, project construction, and project closing, and each section describes what must be accomplished during that phase. Additionally, three recommendations—(1) combining intelligent technology to optimize the existing equipment, (2) utilizing lean technology in project execution, (3) establishing strategic partnerships with construction waste recycling enterprises—are also made for the development of the shield spoil utilization project. This study uses the Shenzhen Metro Line 13 North Extension Project as a model to theoretically underpin future research on shielding spoil on-site during resource utilization projects and to achieve the repeatable promotion of shield spoil utilization technology in Shenzhen. Full article

Backfilling a giant karst cave with grouted engineering spoil as a new countermeasure for tunnels through giant karsts cave is studied in this paper. The numerical models of sections with different distribution characteristics of karst cave and tunnels are established for studying the deformation of surrounding rock and mechanical response of tunnel lining with and without grouting, respectively. The results illustrate that the countermeasure scheme is feasible. In order to ensure that the countermeasure can perform as expected effect, the inadequate grouting sections are recognized and verified using field grouting records and single-hole grouting quantity analysis. Finally, the application effect of the countermeasure scheme is evaluated by field monitoring of horizontal convergence. The result shows that the grouting can reduce the deformation of surrounding rock at the side wall and bottom of tunnel by 70–80% and reduce the stress redistribution range of surrounding rock. However, due to the great differences between the limestone and engineering spoil, the grouting cannot change the share of distribution of load between corresponding region surrounding rock, the max principle stress of tunnel lining is almost identical with and without grouting. The grouting reinforced engineering spoil backfill the giant karst cave can meet the requirement of excavation stability. The inadequate grouting sections caused by groundwater and through crack are identified effectively, and are verified by coring observation method. The horizontal convergence of the tunnel is less than 30 mm, and the stable state can be reached within 20 days, which demonstrate that the remarkable engineering results is achieved. The countermeasure of giant karst cave can provide a useful reference for similar project. Full article

Per- and polyfluorinated alkyl substance (PFAS) contamination has been found in the construction spoil of many major projects, and there is growing concern about the health and environmental implications of these “forever” chemicals. In a context where construction and tunneling have experienced substantial growth, Australia and other countries are still developing their PFAS management. This study used convergent interviews to surface the key common issues that are associated with the management of PFAS contamination in the construction industry. The construction industry appears stuck in their ways and extremely financially driven. Regulation is not working because of poor enforcement and policing from the Environmental Protection Agency (EPA). The EPA could look to employ individuals with more construction industry experience in order to become a strong regulator in the industry, as well as to streamlining decision-making processes, while maintaining quality. To speed up changes in the management of PFASs within the construction industry, large organizations could be targeted by the relevant sustainability rating scheme, and there could be further use of the alliance models to research, develop, and implement PFAS treatment methods. Full article

Mechanized excavation of tunnels with Earth Pressure Balance-Tunnel Boring Machines requires the use of foaming agents. The latter contain the anionic surfactant sodium lauryl ether sulphate (SLES) as the main compound. The re-use as a by-product of excavated soil containing foaming agents (spoil material) can pose a risk for soil and particularly for aquatic ecosystems if they are close to the spoil material final destination site. This work reports the chemical results (SLES residual concentrations) and ecotoxicological effects (battery of five tests) of 28 day-mesocosm studies performed at a tunnelling construction site. The soil mesocosms were set up with two different lithologies, which contained four different foaming agent products at the highest amounts used for excavation. The decrease in SLES concentrations and the ecotoxicological tests were performed in soil and its water extract (elutriate) at different times (0, 7, 14, 28 d). Elutriates were prepared in order to simulate a possible SLES leaching from soil to water. The results showed a decrease in SLES over time and different ecotoxicological responses depending not only on the initial amount of each product, but also on the soil lithology and organism tested (aquatic or terrestrial). This study showed how only site-specific ecotoxicological evaluations can ensure a safe management of the spoil material, making possible the re-use of soil and avoiding production of waste. Full article

Clinker production is very energy-intensive and responsible for releasing climate-relevant carbon dioxide (CO₂) into the atmosphere, and the exploitation of aggregate for concrete results in a reduction in natural resources. This contrasts with infrastructure development, surging urbanization, and the demand for construction materials with increasing requirements in terms of durability and strength. A possible answer to this is eco-efficient, high-performance concrete. This article illustrates basic material investigations to both, using eco-friendly cement and recycled aggregate from tunneling to produce structural concrete and inner shell concrete, showing high impermeability and durability. By replacing energy- and CO₂-intensive cement types by slag-pozzolanic cement (CEM V) and using recycled aggregate, a significant contribution to environmental sustainability can be provided while still meeting the material requirements to achieve a service lifetime for the tunnel structure of up to 200 years. Results of this research show that alternative cements (CEM V), as well as processed tunnel spoil, indicate good applicability in terms of their properties. Despite the substitution of conventional clinker and conventional aggregate, the concrete shows good workability and promising durability in conjunction with adequate concrete strengths. Full article

A wide use of foaming agents as lubricants is required in mechanized tunneling. Their main component, the anionic surfactant sodium lauryl ether sulphate (SLES), can remain in residual concentrations in soil debris, influencing their potential reuse as by-product. This study aimed at evaluating the environmental fate and effects of a foaming product used for conditioning soils collected from real excavation sites, in the presence/absence of an anti-clogging polymer, both containing SLES. Soil microcosm experiments were set-up and incubated for 28 days. Over time, soils and their water extracts (elutriates) were collected to perform both ecotoxicological tests (Vibrio fischeri, Lepidium sativum, Eisenia foetida, Hetereocypris incongruens, Danio rerio) and SLES analysis. The results showed that, just after conditioning, SLES did not exert any hazardous effect on the organisms tested except for the bacterium V. fischeri, which was the most sensitive to its presence. However, from day seven the toxic effect on the bacterium was never observed thanks to the SLES decrease in the elutriates (<2 mg/L). SLES degraded in soils (half-lives from 9 to 25 days) with higher disappearance rates corresponding to higher values of microbial abundances. This study highlights the importance of site-specific studies for assessing the environmental reuse of spoil materials. Full article

In the construction industry, especially in tunneling or large-scale earthworks projects, huge quantities of excavation material are generated as a by-product. Although at first glance such material is undesirable, in many cases this material, if suitably treated and processed, can be recycled and reused on the construction site and does not necessarily need to be removed and deposited as waste at a landfill. In the simplest case, the material can be used as filling material with the least demanding requirements with regard to rock quality. Material of better quality often can be recycled as aggregate and be used as a substitute for conventional mineral aggregates. This approach generates numerous benefits regarding the costs for material procurement, storage and transport. In addition, reduction in environmental impact and demand for landfill volume can be achieved. The challenge lies in the fact that excavation material is not a standard aggregate in terms of geometric, physical and chemical characteristics and is subject to quality deviations during tunnel driving, mainly depending on the varying geology and applied excavation method. Therefore, preliminary research and experimental testing as well as specific evaluation and continuous examination of the rock quality during tunnel driving is necessary as well as ongoing adjustment of the rock processing plant to finally accomplish a high-quality level of recycled aggregates. This article illustrates the material investigations and treatment processes for the specific example of the Brenner Base Tunnel, the longest underground railway line in the world that is currently under construction. There, material recycling has already been successfully implemented. Full article