Tunnel System Research Articles

Influence of a Landslide on a Tunnel in Loess-Bedrock Ground

By combining model testing and numerical simulation, this paper focuses on the influence of landslides on tunnels in loess-bedrock strata by using the perfect landslide–tunnel system (LTS). A mechanical test and simulation (MTS) system was used to provide thrust for loading and unloading the trailing edge of the slope. A Particle Image Velocimetry (PIV) and 32 cluster strain gauges were adopted to monitor the deformation of the tunnel structure and landslide soil, and the sliding surface, respectively. By means of a numerical simulation, the deformation characteristics of a tunnel crossing loess-bedrock strata are comprehensively described. The influence of a cyclic load on the mechanical behavior and displacement of the tunnel and sliding surface is discussed in detail. The experimental results show that the thrust required for the first landslide is the largest, during multiple loading and unloading. With the increase in loading and unloading time, the sliding thrust gradually decreases and eventually remains stable. The landslide presents a progressive failure mode. There is a stress concentration in the upper part of the tunnel, which causes the secondary sliding phenomenon. The deformation of the sliding surface mainly occurs in the upper soil of the tunnel. The deformation direction of the tunnel is consistent with the sliding direction, and the deformation of the sliding surface mainly occurs in the soil above the tunnel. When disturbed by an external force, the tunnel deforms downward, and, when unloaded, the tunnel has a small rebound deformation. However, with the increase in loading–unloading times, the rebound deformation of the tunnel gradually decreases, and the permanent deformation gradually accumulates until the tunnel fails. The research results can provide reference for the construction and protection of tunnel engineering in loess regions, and have reference value for the control of tunnels crossing landslides.

Root cropping by pocket gophers

Pocket gophers (Geomys spp.) are solitary, root-eating fossorial rodents native to North and Central American grasslands and are presumed to acquire most of their food through excavation of tunnels maintained as part of tunnel systems up to 160 m long1,2. Given that burrowing is 360-3,400 times more energetically costly than surface walking, pocket gophers have high energy requirements3. Roots are scarce at the depths of their tunnels in the sandy soil of our study site (20-64 cm), but here we describe a novel food source for southeastern pocket gophers (Geomys pinetis, hereafter gophers): roots that grow into their tunnels. These roots could supply an average of 21% but up to 62% of their daily basal energetic needs.

Динаміка просторового розподілу, рийна діяльність та кормозапасання у сліпака східного (Spalax microphthalmus)

Original data on the burrowing and foraging activities of the greater blind mole rat (Spalax microphthalmus), which is distributed in the east of Ukraine, are generalised. The population density of this species depends directly on the amount of available food resources at the respective sites. The strategy of food storage forms according to the amount and type of available plant resources and depending on the preservation of natural habitat of mole rats. Their appearance in gardens and homesteads is related to anthropogenic changes of the environment at the dwelling sites of mole rats. The seasonal dynamics of their burrowing activity is well pronounced and includes the creation of a branching system of tunnels in the period of active vegetation of plants as well as the relocation or resettlement of animals in various habitats during the year, their lifetime, and population cycle. The length of tunnels, structure of burrows, and the structure of branched underground galleries are regulated by the density and spatial distribution of food resources. Based on the results of our study, specific features of the activity of the greater blind mole rat during various seasons of the years are described, including their active relocation both underground and on the surface, their burrowing at different horizons, the use of a great variety of food and the volumes of their storage for periods when the vegetation of plants ceases. Features of biotopic distribution and food storage of the greater blind mole rat are described in general and in relation to the species’ expansion into anthropogenically transformed parts of its range, including areas nearby to human settlements. The distribution of storage chambers is analysed, of both temporal chambers near the surface and deep-lying chambers, the ratio of which is about 3 : 1. The storage chambers often contain garden vegetables, although it is related not only to the preferences of mole rats, which are obvious too, but also to the fact that information about the storage chambers (especially deep-lying ones) is usually reported by people combating the mole rats for the stolen harvest. The average volume of low-lying chambers is 5–10 kg (1.0–1.5 buckets), whereas the average volume of deep-lying chambers is 20–30 kg. Data on the content of storage chambers revealed both in homesteads and natural or nearly natural sites are generalised.

온도구배터널 내 재배온도 차이에 의한 찻잎의 생육시기, 아미노산 및 카테킨 함량 비교

The growth time and quality of tea leaf was differed temperature during development and growth for tea plants. The study was to compare growth time, amino acid, theanine and catechin contents by difference of cultivation temperature during development and growth for Camellia sinensis var. sinensis cv. ‘Kemsull; and ‘Yabukita’ from the first harvesting season to the third harvesting season in the temperature gradient tunnel system(TGTS). The sprouting time and growth time of tea leaf in the inner region was earlier compared with the middle and the outer regions at the first harvest season and it was not differed by cultivation temperature at the second and third harvesting seasons in the TGTS. The growth and development period (from 1 bud 1 leaf to 1 bud 5 leaves) at the inner region was earlier from 3 to 17 days compared to the middle and outer regions at the first harvesting season. However, there was no difference of cultivation temperature at the second and third harvesting seasons. Also, the difference of the amino acid and theanine contents was greater by cultivation temperature (inner, middle and outer regions) at the first harvesting season than the second and third harvesting seasons. The catechin content was higher than the second harvesting seasons > the third harvesting season > the first harvesting season, and there was few difference between (-)-epigallocatechin–3- gallate(EGCG) and (-) epicatechin-3- gallate(ECG) contents in cultivars and cultivation temperature in the TGTS. The growth and development time, amino acid and theanine contents were very different at the low time about 20∼22℃ (the first harvesting season) of means cultivation temperature compared with above about 20∼22℃ of means cultivation temperature (the second and third harvesting seasons). Therefore, growth and development time, amino acid and theanine contents for tea leaf may be affected by below and above 20∼22℃ of means cultivation temperature.

Wind tunnel test of gust load alleviation for a large-scale full aircraft model

Wind tunnel test is an important way to test the performance of Gust Load Alleviation (GLA). At present, some component-level wind tunnel tests have been carried out in big aviation countries, but there is a lack of full aircraft model GLA tests. In this study, a set of large-scale GLA test system in low-speed wind tunnel is developed, which includes a gust generator, a five-degree-of-freedom suspension system, a full elastic aircraft model with control system, and gust load measuring devices. Two control schemes based on closed-loop feedback control and open-loop feed forward control are respectively designed and verified by the full-model GLA tests in the wind tunnel. The experimental results show that the designed gust generator can generate a stable wideband, wide-area gust wind field; the suspension support system can sustain static and dynamic stability during wind tunnel test, and enables the model moving in the horizontal, vertical, pitching, rolling and yawing directions. The results show that the closed-loop feedback control can obtain good control performance of reducing the peak values of elastic vibration response induced by gust excitation, but has little effect on suppressing the rigid body motion excited by low-frequency gust, while the open-loop feed forward control presents superior performance in alleviating the high-frequency elastic vibration as well as the low-frequency rigid body motion with more than 40% overall reduction rate.

Spatial Learning and Memory in the Naked Mole-Rat: Evolutionary Adaptations to a Subterranean Niche

Evolutionary adaptation to a subterranean habitat consisting of extensive underground tunnel systems would presumably require adept spatial learning and memory, however, such capabilities have not been characterized to date in naked mole-rats (Heterocephalus glaber) which, like other members of Bathyergidae, are subterranean rodents. The goal of this study was to develop a method for effectively assessing spatial learning and memory by modifying a Hebb-Williams maze for use with these subterranean rodents. Established behavioral tests to assess spatial learning and memory have primarily focused on, and have been optimized for, more typical laboratory rodent species such as mice and rats. In the current study, we utilized species-appropriate motivators, analyzed learning curves associated with maze performance, and tested memory retention in naked mole-rats. Using a modified Hebb-Williams maze, naked mole-rats underwent 3 days of training, consisting of five trials per day wherein they could freely explore the maze in search of the reward chamber. Memory retention was then tested 1 day, 1 week, and 1 month following the last day of training. Performance was analyzed based on latency to the reward chamber, errors made, and distance traveled to reach the reward chamber. Overall, this study established a behavioral paradigm for assessing maze navigation, spatial learning, and spatial memory in subterranean rodents, including optimization of rewards and environmental motivators.

Validation of a Two-Phase CFD Air/Mist Film Cooling Model With Experimental Details—Part I: Development of an Experimental Test Facility

Abstract Film cooling is a cooling technique widely used in high-performance gas turbines to protect the turbine airfoils from being damaged by hot flue gases. Motivated by the need to further improve the turbine hot section cooling performance, a mist/air film cooling scheme is investigated. A small amount of tiny water droplets with an average diameter of about 7 µm (mist) is injected into the cooling air to enhance the cooling performance. One key feature in understanding mist cooling is the ability to capture droplet information. In order to thoroughly investigate a two-phase flow, experimental and computational studies are needed. Designing an experimental setup for a two-phase flow experiment is challenging, therefore, the authors will dedicate this paper as Part I to discuss all the challenges faced in order to create a successful experimental facility for air/mist film cooling while Part II will discuss how to conduct a high-fidelity computational model for air/mist film cooling accompanied with a validation study by including detailed experimental conditions. This paper presents the experimental facility and instrumentation of an air/mist film cooling study with both heat transfer and droplet measurements. A wind tunnel system and test facilities are built. A phase doppler particle analyzer (PDPA) system is employed to measure the two-phase flow characteristics, including droplet size, droplet dynamics, velocity, and turbulence. An infrared camera and thermocouples are both used for temperature measurements. An extensive uncertainty analysis is performed to assist in identifying large uncertainty sources and planning for an experimental procedure. It was found during the experiment design process that resolving the mist agglomeration problem is the key in successfully generating a well-controlled mist/air mixture and reducing experimental uncertainties. The test apparatus has proven to serve the purpose well to investigate mist/air film cooling with both heat transfer and droplet measurements. Selected experimental data are presented.

Influence of asymmetric blockage of the drainage system of a deep-buried tunnel on water gushing

Influence of asymmetric blockage of the drainage system of a deep-buried tunnel on water gushing

Aerodynamic Metrologists Guide to Dynamic Force Measurement

Static aerodynamic force measurement is generally of interest in both low- and high-speed ground test facilities, but dynamic force measurement is typically associated with higher-speed facilities. This work will show that dynamic force measurement is relevant to all aerodynamic metrologists because wind tunnel system dynamics can change the force transducer’s dynamic sensitivity resulting in differences between the static and dynamic sensitivity. In addition, the field of dynamic force measurement will be introduced using realistic wind tunnel scenarios, wherein the wind tunnel system dynamics contribute to increased uncertainty in what would otherwise be considered a static force measurement. A design approach focused on estimating the dynamic response is presented to achieve measurement objectives through the use of static force measurement techniques where possible. To that end, a reduced-order model is developed to characterize the dynamic response of the system, which can serve as a predictive tool in the design process. Then, strategies for characterizing wind tunnel system dynamics to determine acceptable bandwidths wherein the static measurements may be sufficient are discussed. In the event that systems have undesirable dynamic characteristics, which cannot be avoided in the design process, two dynamic compensation techniques to correct the measured signals are discussed.

A new sustainable energy based freeze proof method for drainage system in cold-region tunnels: A case study of Tianshan Shengli Tunnel

In order to solve frost damage problems in cold-region tunnels, a new sustainable energy based freeze proof method for tunnel drainage system is proposed. The method is applied to Tianshan Shengli Tunnel, China as a case study to show the concept and details of tunnel drainage system ground heat exchangers (GHEs) including calculation of active heating length and maximum heating load, design of heat extraction in cross tunnel, the segmented design method. Long-term performance of tunnel drainage system GHEs is also fully discussed. Multi-field simulations are performed to achieve corresponding thermal responses of the tunnel drainage system GHEs. Results show that anti-freezing measures provide an initial heating length 900 m of the drainage system at the entrance of Tianshan Shengli Tunnel during full life cycle. When the tunnel drainage system GHEs are employed, the heating length can be reduced to 600 m. Maximum total heating load of the tunnel drainage system in heating period is 84.40 kW. The calculation method of segmented heating load is suggested for precise prevention and control of frost damage in cold-region tunnels, owing to varying tunnel air temperature with the distance from the tunnel entrance. The use of boiler heating in winter will enhance the compensation between operation and recovery period and provides good long-term performance. This study provides a potential reference for antifreeze design of cold-region tunnels utilizing geothermal energy.

Effectiveness of cluster-based inductive ventilation system in railway tunnels: Case study using full-scale experiment and fire dynamic simulation

A calculation method considering ventilation resistance was proposed for designing a cluster-based inductive ventilation system for a real passenger-dedicated railway tunnel. In the system, jet fans were installed only at the two portals, instead of being arranged along the tunnel. A 20 MW train fire was simulated in Fire Dynamics Simulator (FDS) 6.6 to reproduce the designed fire, and the tunnel ventilation was validated using full-scale ventilation experiments. The simulation results showed that the growth of the ventilation velocities was periodically fluctuating. At a height of 2 m above the rail surface, the temperatures always remained below 60 °C, and the visibilities upstream of the fire were not affected by the smoke. It can be concluded that the designed ventilation scheme can effectively inhibit smoke backflow, and both the cluster-based inductive ventilation system and calculation method are feasible.

Tunnel support practice in small hydropower tunnels in the Himalayas through observational approach

With the high mountains, steep terrain and fast flowing river, the Himalayan region has a great opportunity and potential for hydropower development. In Nepal, many hydropower projects have been constructed and many are under construction among which majority of the project are small to medium scale project. For such project, medium size tunnel provides an economic and safe route for water convergence. Squeezing and collapse have been observed in most of the hydropower tunnels, which have resulted in support failure, as the tunnel passes through weak rock mass under high in-situ stress during construction. Due to insufficient tunnel closure measurements, field-based observation has been conducted to study the installed support at different tunnels in the Himalayas. The observational approach is used for analysis and recommendations have been made for designing a stable and safe support system for tunnels. Through an analysis of a case study from Nepal, comparison has been made on the design and practiced support systems, and description of supports used in various case histories from Nepal have been provided.

3D Monitoring & its Significance in Tunneling: Special Emphasis on Tunnel T-74R of USBRL Project, India

Nowadays, Tunnels are the major transportation network throughout the world. The importance of tunnel and its associated system also increases as the demand of Tunnel construction increases day by day. It has its significant importance in water conveyance networks as well as communication networks. As it is spreading fast over the world, the assessments of deformations are becoming an important part of tunneling system. The paper deals with the 3D monitoring system for the safety perspective and to make proper judgement about the condition of tunnels related to the information obtained in the measuring equipments. It also enables to react under various rock setting with the precise and reliable monitoring results. As we observed in the T-74R tunnel, where deformation of the tunnel’s support system is a natural occurrence, the T-74R’s main support system was also affected. The groundmass is prone to deformation due to its poor state and proximity to the principal thrust. The finding of the T-74R tunnel utilising 3D monitoring devices is important. They have provided the information about actual ground behaviour conditions.

Cover Picture: Geomechanics and Tunnelling 3/2022

AbstractThe A26 Linz Motorway is one of the most important projects to improve traffic situation in Linz as well as in the surrounding area of the Upper Austrian state capital. The first section has been under construction since the beginning of 2019 and consists of an approximately 300 m long suspension bridge over the Danube, which will be anchored in the rocky slopes above the Danube, as well as the two underground motorway interchanges Danube North and South with a total tunnel system of approximately 3200 m in length with driving or main tubes and ramps. (Source: DSI Underground)

Flood Control Strategy Chandoli Reservoir Using Tunnel Construction Approach a Case Study of Warna River in Kolhapur

Abstract: Floods are the most frequent and damaging of all types of natural disasters and annually affect the lives of millions all over the globe. Against this background, enhanced climate variability and climate change are expected to increase the frequency and intensity of floods. There are growing demands for deep tunnels to mitigate severe rural flooding by providing a large tunnelling capacity for excess storm runoff. This study aims to assess the flooding mitigation effect of a deep tunnel system proposed in the old downtown of Kolhapur, India. By providing a sufficient tunnel of a particular type of size, we can reduce the flood force on the downstream side for minimizing the negative impacts of floods, often making the difference between life and death Keywords: Flood, River, Tunnel, Dam, Diversion, Rainfall

Seismic early warning systems for the transport cascade under the “SHIPKA” pass

The report presents an early warning system against earthquakes of the conceptual design of the tunnels under the “Shipka” Pass. Bulgaria gives many victims on the roads - those killed in traffic crashes and accidents. In the case of tunnel facilities in seismic areas, chain accidents in tunnel pipes are particularly dangerous. Early warning systems for tunnels make it possible to immediately stop traffic by the traffic police or automatically, to include additional ventilation equipment and turn on the additional reserve lighting installations.

Research and Application of a Prefabricated Spatial Reticulated Shell Support System for Large Cross-Section Tunnel in a Complex Urban Environment

To solve the technical problems of slow construction progress, low mechanization and high risk of shallow buried large cross-section tunnels in a complex urban environment, a series of spatial reticulated shell (SRS) support structures are developed in this paper. Moreover, the equipment of a multifunctional operation trolley is developed to install the SRS arch, and the construction technology system of the prefabricated SRS structure is proposed for a large cross-section tunnel. Therefore, the deformation characteristics of the end-plate joint component and jointless component are clarified by laboratory experiments. The construction mechanics’ simulation of the SRS arch is performed to obtain the tunnel deformation and structure stress based on the tunnel project of Panyu Square Station of Guangzhou Metro. A field application of the prefabricated SRS arch is carried out to realize the mechanized construction operation. The obtained results reveal that the end-plate joint component has better ductility, and its ultimate bearing capacity is basically consistent with the jointless component. The SRS arch can effectively control the deformation of the surrounding rock, improve the stress state of the structure, and reduce the plastic zone of shotcrete by numerical simulations. The overall stress of the SRS arch by field measurement represents the characteristics of “bigger on the upside and smaller on the downside” and “uneven symmetry”. Additionally, the successful application of the prefabricated SRS arch provides a scientific reference for mechanized construction of large cross-section tunnels.

Study of Electronic and Transport Properties in Double-Barrier Resonant Tunneling Systems.

Resonant tunneling devices are still under study today due to their multiple applications in optoelectronics or logic circuits. In this work, we review an out-of-equilibrium GaAs/AlGaAs double-barrier resonant tunneling diode system, including the effect of donor density and external potentials in a self-consistent way. The calculation method uses the finite-element approach and the Landauer formalism. Quasi-stationary states, transmission probability, current density, cut-off frequency, and conductance are discussed considering variations in the donor density and the width of the central well. For all arrangements, the appearance of negative differential resistance (NDR) is evident, which is a fundamental characteristic of practical applications in devices. Finally, a comparison of the simulation with an experimental double-barrier system based on InGaAs with AlAs barriers reported in the literature has been obtained, evidencing the position and magnitude of the resonance peak in the current correctly.

INFLUENCE OF MIDDLE EAST ARMED CONFLICTS INTO BATTLEFIELD CHANGES

Wars conducted in the Middle East after the WWII significantly affected the course of military strategy, and combat tactics, and military technology. Presented paper describes circumstances of local wars and military conflicts in the Middle East and their influence on development of warfare art and technology. The wars with Israel which were lost by the Arabic countries in 20th century affected development of military strategy and tactics of using the armoured weapons and air forces. They contributed significantly to development of the intelligence, and antiaircraft combat assets, and antitank weapons. In consecutive wars the Arabic countries were not able to coordinate military operations, what gave possibility for the Israel army to successively defeat armies of particular countries. Military conflicts between Israel and Hamas and Hezbollah, and suffered losses, caused the development of new revolutionary combat assets such as combat vehicles active self-defence systems (Trophy), or antimissile/antiaircraft systems (Irone Dome). Unmanned aerial vehicles (UAV), drones, and precise weapons were widely used. Reconnaissance and military intelligence affected significantly the results of military operations. Palestinian and Lebanese organisations counterweighed the advantages of Israelian army by systems of fortifications, tunnels, and hidden fire positions. Israelian army implemented combat vehicles in urban area fights. They proved to be efficient what denied opinions about uselessness of armoured weapons at urban fights, or even the tanks in the 21st century. The war in Syria indicated the efficient use of combined combat tactics, conventional military operations, and guerrilla and terrorist methods and actions.The high morale represented by Hezbollah and ISIS fighters proved to be an essential component of military operations. Risking own life at fighting the enemies made great impression on them, and disorganised the defence, and provided dazzling successes in the battlefield. Aviation played important role in all operations fighting the forces of Arabic countries, Hamas, Hezbollah, or Islamic State (IS).

Muscle Hypertrophy in a Newly Developed Resistance Exercise Model for Rats.

Clinical evidence suggests that resistance exercise exerts health benefit. The mechanisms underlying such health benefits is largely explored in experimental animals. Available experimental models have several shortcomings such as the need for noxious stimuli that could affect the physiological readouts. In this study, we describe a simple-to-use experimental model of resistance exercise. In this resistance exercise, rats pull pre-determined weights using a tunnel and pulley system. We show that resistance-exercised rats developed a larger pulling strength when compared to those seen in either control rats or in rats subjected to traditional treadmill exercise. Histological examination revealed that resistance exercise led to a larger fiber cross-sectional area in the plantaris muscle, but not in the gastrocnemius or the soleus muscles. Similarly, the percentage of type-II muscle fibers in the plantaris was increased in resistance exercised rats when compared to those seen in plantaris muscles of either control or treadmill-exercised rat groups. Furthermore, this resistance exercise led to a significant increase in the expression levels of the phosphorylated protein kinase B; a marker of muscle hypertrophy in the plantaris muscle. Such effects were not seen in treadmill-trained rats. In conclusion, we developed an experimental model that can be amenable for experimental exploration of the mechanisms underlying the beneficial effects of resistance exercise. We further provide evidence that this resistance exercise model enhanced muscle strength and muscle hypertrophy.