Investigation of new confined concrete-filled aluminum tube piles: Experimental and numerical approaches

This research aims to introduce and test a Confined Concrete-Filled Aluminum Tube Pile (CCFAT) as an innovative composite pile that embodies a distinctive amalgamation of favourable material characteristics. Experimental tests were carried out to achieve this goal by analysing the vertical and lateral responses of various configurations and slenderness ratios (Lm/D) (ranging from 10 to 20) of CCFAT piles. As a reference group, two traditional piles were also manufactured and tested under identical conditions for comparison purposes. Additionally, the finite element approach was applied to validate the experimental results. The findings indicated that CCFAT piles have either higher or at least equivalent ultimate vertical capacity to that of reference piles. Additionally, the results proved the superior ultimate lateral capacity of the CCFAT piles compared to the reference ones. The results also showed a constant maximum bending moment dept in the CCFAT piles with a Lm/D ratio of 10, with a slight increase observed for CCFAT with a Lm/D ratio of 20 under lateral loading, which could be attributed to the rigidity of the CCAFT piles. Moreover, the outcomes of the finite element analysis indicated that both ultimate vertical and lateral capacities improve with the increase in the number of piles. The sensitivity analysis showed that the dilatancy angle plays the most important role in determining the vertical capacity of the piles, while the lateral capacity was significantly determined by the internal friction angle. Finally, fitted charts were produced and validated in this study to help researchers estimate the ultimate vertical and lateral capacities of CCFAT piles depending on the stiffness of the pile groups

Eco‑friendly remediation of tetracycline antibiotic from polluted water using waste‑derived surface re‑engineered silica sand

A new green reactive adsorbent (calcium ferric oxide silica sand (CFO-SS)) made from wastepaper sludge ash and ferric ions was synthesised and shown to remove tetracycline antibiotics (TC) from contaminated water effectively. The synthesised sand was dried at 95 °C, and a series of batch and fixed bed experiments were performed to determine the optimum operating conditions. Results showed that the adsorption capacity of the CFO-SS increases with the concentration gradient between the solid and liquid phases. 0.3 g of the new adsorbent was proven sufficient to remove more than 90% of the TC at a pollutant dose of 50 mg/L in 50 mL of simulated groundwater with an agitation speed of 200 rpm for 3 h. The adsorption isotherm followed the Langmuir isotherm model, with a loading capacity of 21.96 mg/g at pH 7, while the Pseudo second-order model best described the absorption kinetics. The adsorption mechanisms proposed included electrostatic interaction, intraparticle diffusion, hydrogen bonding, and cation-π interactions. Characterisation investigations revealed that the newly precipitated oxides on silica sand play an essential role in TC adsorption support. In fixed-bed experiments, it was discovered that reducing the flow rate and inflow concentration of TC and increasing the sorbent mass significantly extended the lifetime of the produced sorbent in the packed column. The measured breakthrough curves were best fit with the Adams-Bohart and the Clark models, as they provided the highest square root number (R2) values. Finally, considering the efficacy of CFO-SS in TC adsorption performance, it can be noted that the novel synthesised reactive material is an efficient and environmentally friendly material for TC removal, and it presents a potential solution to resolving the challenge of TC-rich groundwater

A comprehensive review for groundwater contamination and remediation: occurrence, migration and adsorption modeling

Provision of safe water for people is a human right; historically, a major number of people depend on groundwater as a source of water for their needs, such as agriculture, industrial or human activities. Water resources have recently been affected by organic and/or inorganic contaminants as a result of population growth and increased anthropogenic activity, soil leaching, and pollution. Water resource remediation has become a serious environmental concern since it has a direct impact on many aspects of people’s lives. For decades, the pump-and-treat method has been considered the predominant treatment process for the remediation of contaminated groundwater with organic and inorganic contaminants. On the other side, this technique missed sustainability and the new concept of using renewable energy. Permeable reactive barriers (PRBs) have been implemented as an alternative to conventional pump-and-treat systems for remediating polluted groundwater because of their effectiveness and ease of implementation. In this paper, a review of the importance of groundwater, contamination, the biological, physical besides the chemical remediation techniques have been discussed. In this review, the principles of the permeable reactive barrier’s use as a remediation technique have been introduced along with commonly used reactive materials and the recent applications of the permeable reactive barrier in the remediation of different contaminants, such as heavy metals, chlorinated solvents and pesticides. This paper also discusses the characteristic of reactive media and contaminants uptake mechanisms. Finally, remediation isotherms, the breakthrough curves and kinetic sorption models are also being presented. It has been found that groundwater could be contaminated by different pollutants and must be remediated to fit the human, agricultural and industrial needs. PRB technique is an efficient treatment process that is an inexpensive alternative for the pump and treat procedure and represent a promising technique to treat groundwater pollution

Dynamic calibration of slab track models for railway applications using full-scale testing

Research and development of technology for railways has found new impetus as society continues to search for cost effective and sustainable means of transport. This tasks engineers with using the state-of-the-art science and engineering for rolling stock development and advanced technologies for building high performance, reliable and cost-effective rail infrastructures. The main goal of this work is to develop detailed and validated three-dimensional slab track models using a finite element formulation, which include all components of the infrastructure. For this purpose, the parameters of the computational models are identified by performing full-scale tests of the fastening system and of the slab track, including all its material layers. The computational model proposed here is calibrated using this approach and a good agreement is obtained between experimental and numerical results. This work opens good perspectives to use this reliable track model to study the interaction with railway vehicles in realistic operation scenarios in order to assess the dynamic behaviour of the trains and to predict the long-term performance of the infrastructure and of its components

FULL FACE TUNNEL EXCAVATION IN SOILS

In this paper the different methods and implications of full-face tunnel excavation in soils are analysed through numerical FEA (Finite Element Analysis) software and compared with construction monitoring data, empirical predictions and previous analysis from studied literature. A 2D plane strain analysis of a section of the Milan metro-line 5 was conducted under free field conditions using PLAXIS software to display its impact on ground settlements and deformation around the tunnel face. The results found that the FEA model produced an accurate prediction of the settlement troughs, impact of the grouting pressure, and construction of the second tunnel tube on the final induced settlements. Empirical prediction equations were also used to fit Gaussian curves against the numerical curves which produced an accurate alignment of trough width to the numerical prediction

A Systematic Review of the Geotechnical and Structural Behaviors of Fiber-Reinforced Polymer Composite Piles

Composite piles have emerged as a popular alternative to conventional piling materials for deep foundations and have gained significant traction as a specific type of pile due to their potential to mitigate durability issues often associated with standard piling materials. A new type of composite piles can improve structural behavior and extend service life. This research uses an inclusive review methodology to evaluate the geotechnical and structural behaviors of fiber-reinforced polymer (FRP) composite piles. Scopus was utilized to address the relevant keywords and state-of-the-art documents, and VSOviewer software was adopted to spot recurring patterns in the data using scientometric maps. Low-stiffness composite materials are a concern, according to the research work. Thus, researchers are working on confined concrete-filled FRP piles to improve the structural and geotechnical properties used in various load-bearing conditions. However, more research is required to comprehensively understand the behaviors of the studied types of composite piles. Indeed, there is a need for large-scale lab and field studies to determine how axial and lateral loads influence composite piles. This could help create guidelines for constructing the reviewed types of composite piles