Tunnel System Research Articles

Shaking table test on anti-seismic characteristics of NPR anchor cable support system for tunnel crossing faults

Shaking table test on anti-seismic characteristics of NPR anchor cable support system for tunnel crossing faults

Performance of various water-based fire suppression systems in tunnels with longitudinal ventilation

Low pressure, medium pressure and high pressure water-based fire suppression systems were tested in a medium scale tunnel (scale 1:3). The primary objective was to investigate which of these systems are most effective in the suppression or control of different types of tunnel fires. The default low, medium and high pressure systems refer to full scale water flow rates of 10 mm/min, 6.8 mm/min and 3.7 mm/min, respectively. Some other water densities were also tested to investigate the effects, as well as different ventilation velocities and activation criteria. Several series of fire tests were conducted for different fire scenarios. The fire scenarios considered included idle wood pallet fires, loosely packed wood crib fires, loosely packed wood and plastic crib fires, and pool fires, with or without a top cover on the fuel load. Comparisons of the three default systems based on the three parameters: heat release rate, energy released and possibility of fire spread, show that the performance of the default low pressure system is usually the most effective based on the parameters studied. The default high pressure system usually yields results less effective in comparison to the default low pressure system. The performance of the default medium pressure system usually lies in between them. The high pressure system behaves very differently in comparison to the others, in terms of tunnel ventilation velocity, water density, operating pressure, and the presence of the top cover.

Tunnel fire safety management and systems thinking: Adapting engineering practice through regulations and education

Society is changing ever faster, and tunnels are complex systems where performance is affected by many different stakeholders. These conditions suggest that safety management needs to be proactive and based on a systems perspective that acknowledges socio-technical theories. Although systems thinking principles are foundational in overarching European regulations and goals, system principles generally don't affect tunnel fire safety design principles or engineering practice. In the countries investigated in this study, tunnel fire safety management (TFSM) builds on experience-based and risk management-based principles that are optimized independently system by system. This is usually done with limited consideration of how these systems are interconnected and affect the overall tunnel system. The purpose of this paper is to investigate how systems thinking could support existing engineering practice. The work presented in this article is the outcome of a collaboration between fire safety researchers and practitioners from five countries and three continents. Through three workshops, current TFSM principles have been compiled and discussed. It is suggested that tunnel safety regulations be redesigned to strengthen the ability of engineers to work in design teams using systems thinking principles.

Analysis of water pressure distribution and optimization of waterproof-drainage system for tunnels in water-rich region

Analysis of water pressure distribution and optimization of waterproof-drainage system for tunnels in water-rich region

Frost protection mechanism based on rubber airbag interlayered composite lining system for cold-region tunnels

To solve the problem of freezing damage in cold-region tunnels, this study proposed a rubber airbag interlayered composite lining system, and tested its performance of buffering, pressure adjustment, waterproofing, and heat preservation by simulating a low-temperature environment in an artificial freezing chamber. The experiment results show that the frost-heaving force exerted on the lining can always be lower than 1.69 kPa by constantly adjusting the airbag pressure, and the maximum frost-heaving force can reach 28.25 kPa without the airbag. In addition, the airbag also has good waterproof performance. Finally, the airbag can significantly improve the temperature field of the surrounding rock and reduce the freezing depth (6.75 cm < 17.25 cm). The insulation effect of the airbag is positively correlated with its thickness and negatively correlated with the thermal conductivity of the filling gas. The insulation effect of CO2 is better than that of air. The rubber airbag interlayered composite lining system provides a new scheme for freezing damage control in cold-region tunnels.

Development of an artificial intelligence based occupational noise induced hearing loss early warning system for mine workers.

Occupational Noise Induced Hearing Loss (ONIHL) is one of the most prevalent conditions among mine workers globally. This reality is due to mine workers being exposed to noise produced by heavy machinery, rock drilling, blasting, and so on. This condition can be compounded by the fact that mine workers often work in confined workspaces for extended periods of time, where little to no attenuation of noise occurs. The objective of this research work is to present a preliminary study of the development of a hearing loss, early monitoring system for mine workers. The system consists of a smart watch and smart hearing muff equipped with sound sensors which collect noise intensity levels and the frequency of exposure. The collected information is transferred to a database where machine learning algorithms namely the logistic regression, support vector machines, decision tree and Random Forest Classifier are used to classify and cluster it into levels of priority. Feedback is then sent from the database to a mine worker smart watch based on priority level. In cases where the priority level is extreme, indicating high levels of noise, the smart watch vibrates to alert the miner. The developed system was tested in a mock mine environment consisting of a 67 metres tunnel located in the basement of a building whose roof top represents the "surface" of a mine. The mock-mine shape, size of the tunnel, steel-support infrastructure, and ventilation system are analogous to deep hard-rock mine. The wireless channel propagation of the mock-mine is statistically characterized in 2.4-2.5 GHz frequency band. Actual underground mine material was used to build the mock mine to ensure it mimics a real mine as close as possible. The system was tested by 50 participants both male and female ranging from ages of 18 to 60 years. Preliminary results of the system show decision tree had the highest accuracy compared to the other algorithms used. It has an average testing accuracy of 91.25% and average training accuracy of 99.79%. The system also showed a good response level in terms of detection of noise input levels of exposure, transmission of the information to the data base and communication of recommendations to the miner. The developed system is still undergoing further refinements and testing prior to being tested in an actual mine.

Towards field deployment of MAVs in adaptive exploration of GPS-denied subterranean environments

Exploration and safe navigation in previously unknown GPS-denied obstructed areas are major challenges for autonomous robots when deployed in subterranean environments. In response, this work establishes an Exploration-Planning framework developed for the real-world deployment of Micro Aerial Vehicles (MAVs) in subterranean exploration missions. The fundamental task for an autonomous MAV to navigate in an unknown area, is to decide where to look while navigating such that the MAV will acquire more information about the surrounding. The work presented in this article focuses around 3D exploration of large-scale caves or multi-branched tunnel like structures, while still prioritizing the Look-Ahead and Move-Forward approach for fast navigation in previously unknown areas. In order to achieve such exploration behaviour, the proposed work utilizes a two-layer navigation approach. The first layer deals with computing traversable frontiers to generate the look ahead poses in the constrained field of view, aligned with the MAV’s heading vector that leads to rapid continuous exploration. The proposed frontier distribution based switching goal selection approach allows the MAV to explore various terrains, while still regulating the MAV’s heading vector. The second layer of the proposed scheme deals with global cost based navigation of the MAV to the potential junction in a multi-branched tunnel system leading to a continuous exploration of partially seen areas. The proposed framework is a combination of a novel frontier goal selection approach, risk-aware expandable grid based path planning, nonlinear model predictive control and artificial potential fields based on local reactive navigation, obstacle avoidance, and control for the autonomous deployment of MAVs in extreme environments.

Numerical Study on the Efficiency of the Point Smoke Exhaust System in V-shaped Urban Underground Road Tunnel

In order to study the exhaust effect of the point smoke exhaust system in V-shaped urban underground tunnel with different structures, effects of the slope differences on both sides of the slope changing point and the operating mode of the exhaust vent on the smoke spread distance, temperature at the height of 2 m above the road and the ceiling temperature were studied by the numerical method. The research results show that for the symmetric V-shaped tunnel, smoke can be controlled in the required range, but for asymmetric V-shaped tunnel with the slope difference on both sides, smoke cannot be easily controlled, ventilation supply is needed to improve the smoke exhaust efficiency. Point smoke exhaust system cannot effectively reduce the maximum temperature of the ceiling above the fire. When the fire source power is large, for the symmetrical V-shaped tunnel with a small slope, some fire prevention measures must be taken to protect the ceiling partition. For the asymmetric V-shaped tunnel, two exhaust vents opened on the small slope side and four opened on the large slope side are suggested for the occupant safe evacuation in tunnel.

Deep Learning Network for Remote Monitoring of Thermal Exchange Tunnels

Monitoring and predicting ground settlement throughout tunnel construction is critical to ensuring the safe and accurate use of urban tunnel systems. The accurate and efficient diagnosis of such settlement can decrease hazards while improving the safety and dependability of these initiatives. However, typical tunnel inspection procedures are time-consuming, costly, and heavily reliant on human subjectivity. The trained model's accuracy was evaluated by comparing its findings across extended operating durations using the same and different thermal operational patterns as those utilized for training. Deep learning, one of the most powerful Artificial Intelligence approaches, is required for the tunnel's settlement predicting challenge. Nevertheless, deep neural networks frequently want huge quantities of training data. In the method we used, CNN-LSTM models were trained on datasets of various sizes and attributes. The results suggest that both of the proposed models may achieve a little inaccuracy under specific situations.

RETRACTED: Subway structure health monitoring system based on internet of things

The present study advances the metro structure monitoring system, which has been hindered by technological constraints limiting the comprehensive and precise collection of vital data from shield tunnels. We introduce a metro tunnel health advisory system that leverages a compressed sensory reconstruction algorithm and wavelet transform to integrate and alert the 3D model of metro tunnels. Additionally, we propose a novel wavelet packet spectrum multi-threshold noise reduction method, based on the categorization of the wavelet packet spectrum and a threshold criterion for signal noise reduction. Our findings reveal that the threshold UL enables precise determination of the structure's damage state. Moreover, the BIM-based IoT metro health monitoring system has been effectively deployed in Wuhan Metro Line 3's monitoring project, proving the technique's capability to accurately trace the full progression of structural damage. This approach offers fresh insights for designing primary content, selecting transmission schemes, analyzing early warnings, and visualizing the health monitoring system of operational tunnels.

Tolerance to fluctuating currents in farmed Atlantic salmon: a novel method to simulate offshore wave effects in the laboratory

To ensure acceptable animal welfare in emerging offshore Atlantic salmon aquaculture, it is crucial to understand the biological limits of the fish. Much work has been done on the effects of water currents, but few studies exist on waves, owing to logistical limitations. The purpose of this study was therefore to establish a method to replicate wave-like fluctuating water currents in the laboratory and quantify tolerance limits in salmon. To accomplish this, a swim tunnel system was modified so that current speeds could be programmed to automatically alternate between minimum and peak speeds of a desired magnitude and interval. The critical swimming speed (Ucrit) was subsequently measured in salmon of &amp;#126;800 g as a baseline from which standardized tests of fluctuating currents could be prescribed. Fluctuating current trials were then performed using minimum speeds of 20% Ucrit and peak speeds of 80, 100, 120, and 140% Ucrit, and cycles of 0.5, 1, and 2 min. Fish were tested for 4 h or until they fatigued. All fish at 80 and 100% Ucrit endured 4 h of fluctuating currents. However, at 120% Ucrit, only 17% completed the test, and at 140% Ucrit, all fish became fatigued within 1.5 h, thus defining acute limits to fluctuating peak speeds. Wave interval did not affect fatigue times significantly. In conclusion, a novel method is introduced here to assess tolerances to various wave-like environments, showing that salmon can endure &amp;#126;20% higher peak speeds in dynamic fluctuating currents when compared to known swimming capacities at constant speeds.

NEOICHNOLOGY OF TROPICAL AND ARID SCORPIONS: ENVIRONMENTAL IMPACTS ON BURROW CONSTRUCTION AND FORM

ABSTRACT Scorpions are intermediate predators in numerous terrestrial environments, and many are temporarily to permanently fossorial. As a result, they play key roles in terrestrial food webs, in soil development, and as ecosystem engineers. However, scorpions have a poorly described ichnofossil record likely due to an inadequate understanding of their trace morphology. Critical to correcting this is assessing the variability of burrows constructed by phylogenetically, geographically, and environmentally distinct scorpions. Five extant scorpions, Heterometrus spinifer, Pandinus imperator, Pandipalpus viatoris, Hadrurus arizonensis, and Paravaejovis spinigerus were studied through neoichnological experiments under varying substrate conditions. Burrow casts produced were described and compared across species and different substrate conditions. Tropical scorpions excavated sediment and carried it away from the burrow to produce open, straight-to-sinuous, subvertical tunnels to branching tunnel systems with single to multiple entrances and often chambers. Arid scorpions excavated with rapid leg movements to throw sediment behind the body to produce single to linked networks of U-shaped burrows as well as subvertical tunnels to tunnel networks with single to multiple entrances and rarely chambers. Changes in sediment composition and moisture tended to reduce burrow production but did not significantly alter burrow morphology. All scorpion burrows, regardless of species, bore a moderate-to-high similarity despite differences in excavation styles and architecture suggesting that scorpions produce burrows of consistent form regardless of phylogenetic or environmental distance. The result of these studies provides key ichnotaxobases of scorpion burrows which can be used to identify them in the fossil record and improve interpretations of ancient terrestrial ecosystems.

Comparison of baiting strategies in common vole management.

Worldwide, pest rodents can cause extensive damage to agriculture, forestry, food storage, and infrastructure and pose a risk to public health and livestock due to the spread of zoonotic pathogens. In Europe, the most common pest rodent species is the common vole (Microtus arvalis). Management during periodic outbreaks largely relies on rodenticidal bait with zinc phosphide. Efficient baiting with rodenticides or possibly anti-fertility products in the future require baiting methods that allow a sufficient proportion of the population to consume an effective dose of bait. We used a bait with the quantitative marker ethyl-iophenoxic acid (Et-IPA) to evaluate baiting strategies in enclosure experiments. This wheat-based bait with Et-IPA was placed in bait boxes or directly into the tunnel system entrances in different seasons and common vole abundances. Voles were live-trapped, individually marked and blood samples were collected to relate Et-IPA blood residues to bait uptake. The percentage of animals consuming bait was not heavily affected by the baiting strategy but voles had higher Et-IPA blood residues if tunnel baiting was used in autumn and if bait boxes were used in winter. Non-reproductive as well as lighter animals tended to have higher Et-IPA blood residues than reproductive individuals, whereas sex had no effect. Population density had a negative effect on the probability of residues present as well as on Et-IPA blood concentration. The results of this study might help to improve baiting techniques to manage overabundant rodent pest species regardless of the compounds to be delivered. © 2024 Julius Kühn-Institut. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Design of Wind Speed Measurement System in Wind Tunnel Based on Pitot Tube

In the current era, the development of science in all aspects continues to change. The use of wind at this time is necessary for the efficiency of the energy used. The wind speed research method for this study utilizes experimental laboratory methods, specifically employing a Pitot tube measuring instrument to collect wind speed data. From the wind speed data obtained using a frequency of 25–50 Hz, there is only a slight difference between readings from a testometer with a pitot tube and only at frequencies of 39 Hz and 43 Hz, which have a visible difference. The graph indicates that the research was successful by comparing the readings on the testometer.

Comprehensive analysis of renewable hybrid energy systems in highway tunnels

In order to explore the feasibility of a renewable hybrid energy system in highway tunnels, a scenario-coupled construction method for a highway tunnel renewable hybrid energy system is proposed. Based on this method, a tunnel on a highway in southern China serves as an example, and a renewable hybrid energy system for the highway tunnel is constructed. Using HOMER, the hybrid energy system is simulated, optimized, and analyzed, studying the characteristics of the operation of the highway tunnel hybrid renewable energy system in an off-grid mode. The optimal configuration for the hybrid energy system is proposed. The research results indicate the feasibility of constructing a highway tunnel renewable hybrid energy system by utilizing natural resources within the road area (solar energy, wind energy). The hybrid renewable energy system for this tunnel can provide 1112392 kWh of electrical energy annually, with the lowest energy cost being $0.17/kW. Furthermore, the hybrid energy system can reduce greenhouse gas emissions, contributing to the sustainable development of the environment.

Risk-based optimization of emergency response systems for accidental gas leakage in utility tunnels

Focusing on the effective configuration of emergency response systems in utility tunnels, this study proposes an innovative approach to optimize existing emergency response systems based on a consequence rapid prediction model and genetic algorithm. In the proposed approach, the interactions between different emergency response components are considered to perform a rapid gas dispersion prediction. Furthermore, the predicted gas concentration distribution is employed to estimate the quantitative explosion risks by combining the equivalent cloud method and the Baker-Strehlow model. Finally, the cumulative and cascading risk index are proposed and combined for systematic optimization by using a genetic algorithm. A case study is performed to demonstrate the feasibility of the proposed approach. The results indicate that the optimized emergency response systems effectively reduce both the cumulative and cascading risk level. This study provides technical support for emergency response system design and helps to improve the safety-risk-control capabilities of utility tunnels.

Enhancing the performance of open geothermal tunnelwater systems by heat absorbers

The symbiotic use of underground infrastructure among the improvement of transport routes and the generation of geothermal power, is increasingly gaining momentum. Geothermal systems can be divided into open and closed systems, which differ from each other by the circumstance that closed systems have a closed circuit and open systems do not. For the application of geothermally closed tunnel systems, elegant solutions have been developed, while geothermally open tunnel systems are still dictated by the characteristics of the water entering the tunnel. In order to address this issue, concepts for tunnels under design as well as existing tunnels, were developed. The concepts allow the temperature of the inflowing water to be risen, and thereby increasing the geothermal power. The presented approach is based on the channeling of cold tunnel water inflows through absorber sections in areas of high overburden to supply them with additional energy before diverting them back into the drainage system. In order to obtain indications on the effectiveness as well as on the sensitivity of the components and influencing parameters, numerical models were created and subsequently compared, since no empirical data are available. The results show that it is possible to enhance the geothermal performance, but with decreasing efficiency over time.

Comprehensive data set of in situ hydraulic stimulation experiments for geothermal purposes at the Äspö Hard Rock Laboratory (Sweden)

Abstract. In this article, a high-resolution acoustic emission sensor, accelerometer, and broadband seismometer array data set is made available and described in detail from in situ experiments performed at Äspö Hard Rock Laboratory in May and June 2015. The main goal of the hydraulic stimulation tests in a horizontal borehole at 410 m depth in naturally fractured granitic rock mass is to demonstrate the technical feasibility of generating multi-stage heat exchangers in a controlled way superiorly to former massive stimulations applied in enhanced geothermal projects. A set of six, sub-parallel hydraulic fractures is propagated from an injection borehole drilled parallel to minimum horizontal in situ stress and is monitored by an extensive complementary sensor array implemented in three inclined monitoring boreholes and the nearby tunnel system. Three different fluid injection protocols are tested: constant water injection, progressive cyclic injection, and cyclic injection with a hydraulic hammer operating at 5 Hz frequency to stimulate a crystalline rock volume of size 30 m × 30 m × 30 m at depth. We collected geological data from core and borehole logs, fracture inspection data from an impression packer, and acoustic emission hypocenter tracking and tilt data, as well as quantified the permeability enhancement process. The data and interpretation provided through this publication are important steps in both upscaling laboratory tests and downscaling field tests in granitic rock in the framework of enhanced geothermal system research. Data described in this paper can be accessed at GFZ Data Services under https://doi.org/10.5880/GFZ.2.6.2023.004 (Zang et al., 2023).

Vibration Response Analysis of a Tethered Unmanned Aerial Vehicle System under Transient Wind Field

The transient wind is one of the dangerous conditions encountered by tethered UAVs operating at the ocean, making the cable and the UAV generate complex nonlinear vibration responses threatening normal operation, even safe flight. There is a lack of research on the nonlinear vibration of the tethered UAV in a transient wind field environment. This study analyzes the vibration response of a tethered quadrotor UAV under a transient wind field, which helps to boost the tethered UAV applications, providing engineering suggestions to design these systems. Considering both cable and UAV motions, the coupled dynamic equations of the tethered UAV system are established based on the Hamilton principle. The variation law of the cable vibration amplitudes with wind field and position is analyzed through a one-minus-cosine gust profile to describe the transient wind field, which can evaluate the dynamic behavior of systems in the actual flight. Moreover, the positions of maximum vibration amplitude in tangential and normal directions are found to be approximately 9/10 and 9/20 from the lower end of the cable. Furthermore, the tethered UAV system vibrations are investigated under different structural parameters. The results indicate that the UAV can maintain a stable single-period motion by increasing the length or elastic modulus or selecting the appropriate diameters of the cable. Finally, an experiment is implemented on the vibration response of the tethered UAV system in a wind tunnel. The theoretical result is compatible with the experimental one, demonstrating the theoretical method’s accuracy.

Interception performance of intake structures with a flow diversion barrier under supercritical flow conditions

Intake structures are commonly used in drainage systems to redirect surface rainfall runoff into underground tunnels. The Hong Kong West Drainage Tunnel (HKWDT) system is designed to capture stormwater from steep upland catchments during periods of heavy rainfall, concurrently maintaining a minimal environmental flow downstream during dry weather. However, during heavy rainfall events, excess rainfall water is often directed into the drainage system, presenting a significant challenge to the urban drainage system. Undistorted Froude scale physical models and computational fluid dynamics (CFD) models are developed to investigate the flow performance. In this study, effects of various design parameters on water diversion performance are examined across a wide range of inflow conditions. Steeper channel bottom slopes leading to a larger proportion of water being directed downstream. Extending the length of the bottom rack effectively reduces adhering flow. Introducing a transverse barrier generates a hydraulic jump, which increases flow diversion into the LFC. With higher barrier heights, the hydraulic jump becomes stronger, facilitating greater water diversion into the downstream sewage system. The results indicate potential solutions to these challenges and provide valuable insights into optimizing flow diversion performance in intake structures, particularly in areas characterized by steep terrains and varying flow conditions.