Tunnel Research Articles

16 years of operation of a road tunnel in swelling rock – results of special measures

16 years of operation of a road tunnel in swelling rock – results of special measures

Application of seismic methods for determining the depth of the rock mass damage zone around the excavation profile by blasting

Research and determination of the blasting damage zone around the profile of tunnels or underground structures is a platform that would serve to confirm or correct blasting parameters and underground assemblies, that is, geotechnical and main tunnel projects. From the obtained research, the stability of the excavation profile, as well as the safety risk for equipment and personnel on the construction site, would be better understood. Considering the importance of the size of the damage zone of the rock mass in terms of its influence on stability, the amount of primary support elements required to achieve the stability of the excavated space, and the additional costs of stabilization of the excavation and the safety of people and equipment, the aforementioned problem was investigated and processed for specific cases and for the rock mass characteristic for the location in question. From the described research, the change in the elastic characteristics of the rock mass and the depth of the damage zone around the tunnel excavation profile were measured and calculated.

Safety assessment of the construction of double track tunnels underneah exsiting railway tunnels

The ground disturbance caused by the tunnel construction will inevitably have an impact on the upper part of the constructed tunnel structure, and the railroad tunnel requires a very high level of control over the structural settlement deformation. For the problem of double-hole tunnel under the built tunnel, this paper takes Chongqing Mingyue Mountain Tunnel under the built Shanghai-Rong Railway Paihua Cave tunnel and Zheng-Yu Railway tunnel as the engineering background, and starts from the mechanism of ground loss caused by tunnel excavation, firstly, the settlement at the height of the existing tunnel strata is obtained through theoretical analysis, and the new Mingyue Mountain Tunnel under the Shanghai-Rong Railway tunnel is determined to be a more dangerous section. Further simulate and calculate the dynamic excavation process of the new double-hole tunnel underpass, and study the settlement deformation law of the Mingyue Mountain Tunnel underpassing the Hurong Railway Tunnel. According to the requirements of railroad tunnel for settlement deformation control, the new tunnel is determined to be constructed by step method to ensure the safety of railroad tunnel. The shortcomings of the theoretical calculation are analyzed to illustrate the important role of numerical simulation in the evaluation of tunnel underpass projects.

Działalność Międzyresortowej Komisji ds. Najwyższych Dopuszczalnych Stężeń i Natężeń Czynników Szkodliwych dla Zdrowia w Środowisku Pracy w 2023 r.

In the sixth phase of the national programme “Governmental Programme for Improvement of Safety and Working Conditions” in 2023, three meetings of the Interdepartmental Commission for Maximum Admissible Concentrations and Intensities for Agents Harmful to Health in the Working Environment were considered, during which: eight documentations of the occupational exposure limit values, a position regarding the extension of the transitional period for the OEL for nitrogen oxide by 3 years for the underground mining and tunnel construction sector, the position of the Cobalt Institute, the Group Expert of Chemical and Dust Agents regarding the proposal of the ECHA Risk Assessment Committee (RAC) for OEL values for cobalt and its inorganic compounds (as Co) and the position of the regarding the exemption for nickel and lead compounds included in the annex to the Regulation of MAC and MAI of 2018. The Interdepartmental Commission for MAC and MAI adopted and submitted to the minister responsible for labour three proposals to amend the list of MAC and MAI in the following scope: introduction of occupational concentration values for five new chemical substances, leaving the current MAC value for the inhalable fraction of glyphosate (herbicide), extension by 3 years of the transitional period for the permissible concentration of nitrogen oxide in the underground mining and tunnel construction sector, i.e. until August 21, 2026, removal of exclusions regarding nickel and lead compounds included in the annex to the regulation on NDS and NDN of 2018 (implementation of Directive 2022/431/EU). The results of the Commission’s activities in 2023 were presented in three notes, communication No. XVI, a popular science publication, at the 23rd PTHP Symposium, and in a brochure entitled “Harmful factors in the work environment - limit values for carcinogenic/mutagenic, reprotoxic substances” as well as regular occupational health and safety training and in postgraduate studies.

Optimization Study of Water Interval Charge Structure Based on the Evaluation of Rock Damage Effect in Smooth Blasting

In tunnel smooth blasting, optimizing the water interval charging structure of peripheral holes is of great significance in improving the effect of smooth blasting and reducing the unit consumption of explosives. Addressing the issue of a single traditional evaluation standard, this paper proposes a composite index evaluation method for rock blasting damage in different zones, and the best charging structure is optimized according to the evaluation results. Taking Liyue Road Tunnel Light Smooth Blasting Project in Chongqing as the Research Background, the numeric models were established with ten kinds of charge structures, the charge structures and explosive quantity were optimized according to the evaluation results, and then the field tests were conducted. The results show that when the length of the water medium at the bottom of the hole is 20 cm, the damage range of the retained rock mass can be controlled while ensuring rock fragmentation. If the length of the water medium at the orifice and in the center of the hole is more than 30 cm, it will affect the superposition effect of the blast stress wave, resulting in under-excavation; in the preferred charge structure, the ratio of the length of the upper and lower explosives reaches 1:3, and the ratio of the length of the water medium is 2:2:1, which achieves a better rock-breaking effect in the field test.

Detection of air- and water-filled cavities beneath concrete plate using electromagnetic and acoustic waves

Underground excavation and tunneling may result in cavities filled with air or water. This study aims to detect cavities beneath underground concrete walls or tunnel linings and assess their risks by estimating the cavity thickness and width using electromagnetic and acoustic waves. In this study, air- and water-filled cavities are simulated, and nondestructive testing methods such as ground penetrating radar (GPR), time domain reflectometry (TDR), and microphones are used to investigate the thickness and width of a cavity beneath a reinforced concrete plate. The results show that GPR signals converted from temporal to spatial scales, combined with TDR measurements, can be used to accurately examine the cavity thickness. However, the examination of the cavity width based on GPR signals remains challenging because of the strong parabolic patterns caused by steel bars. Therefore, this study employs flexibility, which is the ratio of the particle velocity of the structure to the load signal according to the frequency. The flexibility of the concrete plate calculated using microphone signals increases in the cavity section for both air- and water-filled cavities because the flexural vibration mode prevails at the cavity–concrete plate interface. The characteristics of the microphone signals analyzed in the context of flexibility enabled the prediction of the cavity width beneath the concrete plate in both air- and water-filled cavities. GPR and TDR signatures combined with microphone signals can be used for the detection and risk assessment of cavities beneath underground structures when subjected to variations in the groundwater level.

Application and configuration analysis of electric muck transfer equipment in plateau railway tunnel: a case study in southwest China

The burgeoning development of railway construction in plateau regions of southwest China necessitates innovative and environmentally sustainable approaches, particularly in the realm of tunnel construction, where the transfer of muck poses significant operational and environmental challenges. This research, pivoting around the application and configuration of electric muck transfer equipment in plateau railway tunnels, seeks to dissect the potentialities and impediments of transitioning from conventional diesel-powered machinery to electric alternatives, with a spotlight on mitigating environmental impacts and enhancing operational efficiency. Through an analytical lens, the study employs a case study methodology, leveraging data and insights from existing electric equipment models and their applications, provided by major manufacturers in China, to weave a comprehensive narrative around the practicalities, specifications, and challenges embedded in the adoption of electric machinery in plateau environments. The findings unveil a nuanced landscape, where the environmental and operational advantages of electric equipment are juxtaposed against a backdrop of technological, financial, and infrastructural hurdles, thereby crafting a complex tapestry of opportunities and challenges. The research further extrapolates policy recommendations and practical guidelines, advocating for a harmonized amalgamation of governmental policies, technological advancements, and strategic planning to navigate through the identified challenges and optimize the integration of electric equipment in tunnel construction practices. Envisaging future research pathways, the study underscores the criticality of perpetuating technological innovations, policy adaptations, and interdisciplinary research to further refine and enhance the application of electric muck transfer equipment in plateau railway tunnel projects, thereby contributing to the broader narrative of sustainable construction practices in challenging terrains.

Numerical Simulation Study of Midas-Based Tunnel Section Structural Forces and Deformations

The burial depth significantly influences the structural forces and deformations of tunnel sections, playing a crucial role in the safe operation of tunnels. This study focuses on the structural design and deformation analysis in underground tunnel engineering. Utilizing Midas modeling techniques, tunnel models were designed for experimentation to comprehensively explore the impact of tunnel burial depth and key design parameters on structural deformations and safety.(1) The research reveals that design parameters such as tunnel diameter are the dominant factors affecting deformation, lining pressure, and structural displacement.(2) With an increase in tunnel diameter, substantial deformation occurs, and the lining pressure distribution evolves from a "fan-shaped" pattern to a "peach-shaped" pattern. The bottom structure transitions from uplift to slight settlement. (3) The study results provide a rational range of parameter values for tunnel design. Simulation outcomes highlight areas with higher deformation, offering insights for proposing corresponding remedial measures.

The pioneer of intelligent and sustainable construction in tunnel shotcrete applications: a comprehensive experimental and numerical study on a self-sensing and self-heating green cement-based composite

In this study, a self-sensing and self-heating natural fibre-reinforced cementitious composite for the shotcrete technique was developed using Kenaf fibres. For this purpose, a series of Kenaf fibre concentrations were subjected to initial chemical treatment, followed by integration into the cement-based composite containing hybrid carbon nanotubes (CNT) and graphene nanoplatelets (GNP). The investigation encompassed an examination of mechanical, microstructural, sensing, and joule heating performances of the environmentally friendly shotcrete mixture, with subsequent comparisons drawn against a counterpart blend featuring a conventionally synthesized polypropylene (PP) fibre. Following the experimental phase, a comprehensive 3D nonlinear finite difference (3D NLFD) model of an urban twin road tunnel, completed with all relevant components, was meticulously formulated using the FLAC3D (fast lagrangian analysis of continua in 3 dimensions) code. This model was subjected to rigorous validation procedures. The performances of this green shotcrete mixture as the lining of the inner shell of the tunnel were assessed comparatively using this 3D numerical model under static and dynamic loading. The twin tunnel was subjected to a harmonic seismic load as a dynamic load with a duration of 15 s. The laboratory findings showed a reduction in the composite sensing and heating potentials in both cases of Kenaf and PP fibre reinforcement. Incorporating a specific quantity of fibre yields a substantial enhancement in both the mechanical characteristics and microstructural attributes of the composite. An analysis of digital image correlation demonstrated that Kenaf fibres were highly effective in controlling cracks in cement-based composites. Furthermore, based on the static and dynamic 3DNLFD analysis, this green cement-based composite demonstrated its potential for shotcrete applications as the lining of the inner shell of the tunnel. This study opens an appropriate perspective on the extensive and competent contribution of natural fibres for multifunctional sustainable, reliable and affordable cement-based composite developments for today’s world.

Experimental study on the performance of synergistic ventilation system combining shaft with mechanical ventilation in extra-long road tunnels

Ventilation shafts are widely equipped in extra-long road tunnels. Due to the plug-holing phenomenon, it may be impossible to improve smoke extraction performance solely by increasing extraction velocity in a traditional ventilation shaft. Taking reference from practices in mine ventilation shafts, a novel mechanical board-coupled ventilation shaft (MBCS) was introduced. A total of 120 experiments in a 1:20 reduced-scale tunnel model were conducted to validate the effectiveness of the novel shaft. The effects of shaft height, board location, and extraction velocity were investigated, and the interaction dynamic mechanism of synergistic smoke extraction between fan-driven and shaft-driven was revealed. The results indicate that the novel MBCS can achieve better smoke extraction performance as the extraction velocity increases. Besides, compared to the traditional MBCS in our previous study, the smoke extraction efficiency of the novel MBCS improves by 19.8 %, the heat extraction performance improves by 75.7 %. Moreover, based on theoretical and dimensional analysis, a model to analyze the dynamic mechanism of synergistic smoke extraction was established, which may provide positive insights for smoke control and extraction design both in extra-long road tunnels and mine ventilation shafts.

Coupled thermodynamic and thermomechanical modelling for compressed air energy storage in underground mine tunnels

Compressed air energy storage (CAES) in underground mine tunnels using the technique of lined rock cavern (LRC) provides a promising solution to large-scale energy storage. A coupled thermodynamic and thermomechanical modelling for CAES in mine tunnels was implemented. Thermodynamic analysis of air during CAES operation was carried out. Difference in temperature and pressure evolution when considering real air thermophysical properties and varying heat transfer properties, as opposed to a simplified thermodynamic model, was revealed. Elastic plane strain (EPS) analysis was implemented to evaluate the influences of initial stress of the lining structure, quality grades of surrounding rock, thermal effect and the cyclic nature of loadings on mechanical behaviour. 3D elastoplastic damage (3DEPD) analysis considering steel reinforced concrete (SRC) lining was implemented to evaluate the damaged mechanical behaviour. Divergences between EPS analysis and 3DEPD analysis were unveiled. It is suggested that, when it comes to tunnel stability, simplifying the thermodynamic model is of least concern, instead, the initial stress of the lining structure is of critical importance and 3DEPD analysis considering SRC lining shall replace EPS analysis. The insights of this study will provide important guidance for the designing and feasibility study of LRC in mine tunnels for application of CAES.

Full-scale experimental, numerical, and theoretical research on the spatio-temporal evolution of the flow structure in longitudinal and semi-transversal ventilated tunnels

This paper presents full-scale experimental, numerical, and theoretical research on the spatial and temporal structure of airflow for different modes of ventilation system operation in a road tunnel. The tunnel under investigation is equipped with a semi-transverse ventilation system. There are 19 pairs of axial jet fans in each tunnel tube and 164 air supply vents on both sides of a tube located just above the road surface. A set of seven stand poles with mounted vane anemometers were arranged along the tunnel tube axis. Different configurations of axial jet fans and air supply vents were employed, and changes in airflow velocity were recorded. Since the main objective of the study is to achieve a deeper understanding of the examined phenomena, a numerical model of the flows in the tunnel was built, and the acquired data was used to validate it. Some theoretical considerations are provided and also validated. All of this together reveals a very uneven distribution of longitudinal air velocity along the tunnel axis. Then, time constants when switching the fans on and off are determined. It is shown that the time needed to achieve a stable flow after the fans are turned on is in the order of five minutes, and the decay time after the fans are turned off is much longer; it takes about 15 min to calm down the flow. Next, it is determined that the transverse air supply significantly changes the airflow structure: the average longitudinal air velocity at the inlet portal was up to 25% lower than without it, while values at the outlet portal were similar. Finally, it is indicated that axial fans that operate in the suction mode are similarly efficient to those in the pumping mode.

Predicting structure performance of urban critical infrastructure: an augmented attention-based LSTM model

PurposeAccurate prediction of the structural condition of urban critical infrastructure is crucial for predictive maintenance. However, the existing prediction methods lack precision due to limitations in utilizing heterogeneous sensing data and domain knowledge as well as insufficient generalizability resulting from limited data samples. This paper integrates implicit and qualitative expert knowledge into quantifiable values in tunnel condition assessment and proposes a tunnel structure prediction algorithm that augments a state-of-the-art attention-based long short-term memory (LSTM) model with expert rating knowledge to achieve robust prediction results to reasonably allocate maintenance resources.Design/methodology/approachThrough formalizing domain experts' knowledge into quantitative tunnel condition index (TCI) with analytic hierarchy process (AHP), a fusion approach using sequence smoothing and sliding time window techniques is applied to the TCI and time-series sensing data. By incorporating both sensing data and expert ratings, an attention-based LSTM model is developed to improve prediction accuracy and reduce the uncertainty of structural influencing factors.FindingsThe empirical experiment in Dalian Road Tunnel in Shanghai, China showcases the effectiveness of the proposed method, which can comprehensively evaluate the tunnel structure condition and significantly improve prediction performance.Originality/valueThis study proposes a novel structure condition prediction algorithm that augments a state-of-the-art attention-based LSTM model with expert rating knowledge for robust prediction of structure condition of complex projects.

Analysis of large-scale fires in Makkah’s King Khaled Road tunnel using non-gray radiation models

The present study validated a fire dynamic simulation approach for reducing costs and losses in tunnel fire tests. It analyzed various radiation models, including gray, non-gray, and non-gray sooting models. The central processing unit (CPU) run time of the last model was very long, and the model is of little value in practice. The non-gray model was found to be the most accurate and efficient. This model was used to study fire behavior in the King Khaled Road tunnel in Makkah. This was done because the tunnel is small, there aren't many ways to get out, and it's hard to get firefighting teams to a place like Makkah during the Hajj season when there are a lot of people. Results showed that gas temperature, radiation, CO and CO2 concentrations, and air velocity increased with heat release rate, oxygen concentration, and soot yield. The air velocity was overpredicted during the simulations, having consequences for most of the other quantities, and this led to a cooler gas temperature, higher oxygen levels, and lower CO and CO2 concentrations. In addition, it is established that gas temperature and radiation increased when the ambient temperature increased, and oxygen concentration and air velocity were mostly unaffected by changing ambient temperature.

Fire-Retarding Asphalt Pavement for Urban Road Tunnels: A State-of-the-Art Review and Beyond

AbstractWith the rapid urbanization and development of metropolises, urban road tunnels have been constructed at an increasing rate, significantly alleviating urban traffic pressure, and improving urban resilience. Fire hazards have become a major threat to modern road tunnels due to the growing popularity of electric vehicles and high-density transportation of goods, particularly flammable materials. Asphalt pavements, as an essential component of road tunnels, may release harmful effluences and smoke under high temperatures, exacerbating the fire and adding risk to life safety. It is hence critical to investigate fire-retarding asphalt materials and their potential use in urban road tunnels pavements. This paper provides a comprehensive review of fire-retarding asphalt pavements for urban road tunnel pavements. The review covers tunnel fire generation mechanisms, evaluation methods, flame retardants for asphalt pavements, and recent developments in flame retardant technologies. By investigating these aspects, this paper aims to better understand the flammability of asphalt mixtures and asphalt pavements in urban road tunnels, promote the research of flame-retardant technology, and ultimately reduce the damage and loss caused by asphalt road tunnel fire accidents. Additionally, this study identifies the limitations of current research and provides an outlook for future research to contribute to the resilience of urban road tunnel structures and the longer service life of asphalt pavement in semi-closed road tunnels.

CFD-based AHP-TOPSIS decision-making model for gas explosion overpressure mitigation measures in underground utility tunnels

Gas explosion is a highly destructive form of disaster, and it seriously threatens the safety of structures and personnel. The reduction and mitigation measures of gas explosions have been extensively investigated, such as blast walls, safety gaps, and inert gases. Among these numerous measures, how to select the most economical, feasible, and effective measure to reduce the consequences of gas explosions is one of the most important problems faced by decision-makers. Therefore, a CFD-based analytic hierarchy process–Technique for Order Preference by Similarity to an Ideal Solution (AHP-TOPSIS) decision-making model was developed in this study. It combines the subjective experiences of decision-makers with the objective results of CFD numerical simulations, which makes the selected measure more reasonable and effective. The selection of mitigation measures for gas explosion overpressures in the UUT was taken as an example to verify the effectiveness of the proposed decision-making model. Three effective measures proposed in this study (i.e., yve = 10 m, D = 300 μm, yve = 10 m – D = 400 μm) were evaluated using the CFD software Flame Acceleration Simulator (FLACS) and used as target decision measures for the model. The results of the CFD-based AHP-TOPSIS decision-making model show that the measure of yve = 10 m – D = 400 μm is the most appropriate mitigation measure for gas explosion overpressures in the UUT under the evaluation index system, including feasibility, effectiveness, and economy. The results will support the selection of the appropriate overpressure mitigation measure of gas explosions and the blast-resistant design of UUTs.

Effect of unpowered ventilation caps and shaft parameters on fire smoke spread in the natural ventilation tunnel with shafts

Shaft-type natural ventilation offer a sustainable and cost-effective alternative to mechanical systems for the mitigation of smoke hazards. This study investigated the behavior of smoke with the application of unpowered ventilation caps in 1/15 scale shallow-buried urban road tunnels with shafts, and analyzed parameters such as the shaft axis wheelbase, shaft width, shaft width-to-height ratio, and heat release rate (HRR). The results show that the dimensionless HRR as an independent relationship with the dimensionless ceiling temperature rise in both the presence and absence of the unpowered ventilation cap. According to the experimental results, dimensionless length of smoke backlayering increases significantly with the increase of the HRR. In addition, the smoke backlayering length is positively correlated with the shaft width, and the backlayering length decreases and then increases with increases of the axis wheelbase. Moreover, the chimney effect is facilitated with the shaft height increase, which enhances exhaust effect, and the backlayering length decreases with the increase in the shaft height when the aspect ratio is greater than 0.5. Once the critical shaft width-to-height ratio is reached, the change in the shaft height no longer has an effect on the backlayering length. Finally, a dimensionless backlayering length calculation model based on the shaft parameters with different shaft exhaust effects is developed by combining the discriminant factors. The findings have crucial implications for fire prevention and safety management, and provide a valuable reference for future studies and engineering applications.

Real-time semantic segmentation for underground mine tunnel

Semantic segmentation is the underlying technology for many intelligent applications in underground mines. Unlike the ordinary scenario, the lighting of underground mines varies drastically, and there is heavy dust and mist, which results in poor image quality and greatly hinders the application of image semantic segmentation in underground mines. Because there is currently no datasets for underground mine tunnels available, a dataset named Underground Mine Tunnel Semantic Segmentation Dataset (UMTSSD) have to be constructed to support our research. UMTSSD consists of 3461 meticulously annotated images and 17 annotated categories. A real-time semantic segmentation algorithm named Fast Adaptive Deep Dual-resolution Network (FA-DDRNet) which uses Deep Dual-resolution Network (DDRNet) as the backbone is proposed for underground mines. To enhance the semantic segmentation accuracy in underground environment, FA-DDRNet introduces two modules: Fast Adaptive Input Normalization Module (FAINM) and Scale-wise Residual Cascade Module (SRCM). FAINM can autonomously and quickly adjust normal lighting images, weak lighting images, and overexposed images to improve the robustness of semantic segmentation algorithms. SRCM is integrated into the backbone to swiftly fuse multi-scale features in a cascade fashion, resulting in enhanced detection of objects with diverse shapes in underground environment. Finally, our method achieves exceptional performance with a superior inference speed compared to other semantic segmentation algorithms in UMTSSD. The method can realize running in real-time on low computational power embedded devices, which is well adapted to underground environment.

Evaluation of the current technologies used for the physical security and safety of selected railway tunnel portals as a case study in the Czech Republic

The security and safety of the railway tunnels require technical measures, information processes, and trained experts. Proper implementation and integration of these elements is crucial to protect lives, property, and the operation of the rail network. The purpose of this study is to identify and describe technological security and safety measures at the portals of selected railway tunnels greater than 1000 m in the conditions of the Czech Republic and their subsequent evaluation. The method of semi-structured interviews with experts with experience in the implementation of security and safety measures was used for the elaboration. SWOT analysis was used to assess the safety level of selected railway tunnels. The evaluation was carried out based on multi-criteria decision making and pairwise evaluation on the principle of Fuller’s triangle. The technical solutions of two currently known technological solutions in the case study for accident elimination based on lidar detection supplemented by cameras are characterized by fundamental differences. The solution in the Ejpovice tunnel focuses on the detection of objects in the immediate vicinity of the portal or already entered it. The solution in the Březenský tunnel focuses on a larger detection zone extending tens of meters in front of the tunnel portal and is divided into two parts with different logic, the pre-alarm and the alarm itself. Integration of individual elements into a proactive and automated system that uses modern AI-based analytical algorithms and respects the process and technology specifics of the railway environment is important for the safety and security of the railway tunnel.

A multidisciplinary engineering-based approach for tunnelling strengthening with a new fibre reinforced shotcrete technology

This paper describes the relevant research activities that are being carried out on the development of a novel shotcrete technology capable of applying, autonomously and in real time, fibre reinforced shotcrete (FRS) with tailored properties regarding the optimum structural strengthening of railway tunnels (RT). This technique allows to apply fibre reinforced concrete (FRC) of strain softening (SSFRC) and strain hardening (SHFRC) according to a multi-level advanced numerical simulation that considers the relevant nonlinear features of these FRC, as well as their interaction with the surrounding soil, for an intended strengthening performance of the RT. Building information modelling (BIM) is used for assisting on the development of data files of the involved design software, integrating geometric assessment of a RT, damages from inspection and diagnosis, and the characteristics of the FRS strengthening solution. A dedicated computational tool was developed to design FRC with target properties. The preliminary experimental results on the evaluation of the relevant mechanical properties of the FRS are presented and discussed, as well as the experimental tests on the bond between FRS and current substrates found in RT. Representative numerical simulations were performed to demonstrate the structural performance of the proposed FRS-based strengthening technique. Computational tools capable of assuring, in real time, the aimed thickness of the layers forming the FRS strengthening shell were also developed. The first generation of a mechanical device for controlling the amount of fibres to be added, in real time, to the FRS mixture was conceived, built and tested. A mechanism is also being developed to improve the fibre distribution during its introduction through the mechanical device to avoid fibre balling. This work describes the relevant achievements already attained, as introduces the planned future initiatives in the scope of this project.