Full-scale Tunnel Research Articles

Feasibility Study on Transportation Techniques Employing Air-Bearing System for Pre-Assembled Waste Package at Drift Tunnel of HLW Repository

Full-scale tests were performed to evaluate the technical feasibility of a transport system with air-bearings at the underground HLW disposal tunnel for pre-assembled heavy disposal packages, which consist of a waste package and buffer material. Transport conditions in the disposal tunnel, such as roughness and unevenness of the curved surface, make it difficult to achieve smooth movement using the commercial airbearing transport system. In order to evaluate the applicability of the air-bearing transport system to such conditions, tests using a full-scale test device (modified package) and simulated tunnel surface were conducted. Based on the tests, the applicability of this transport system to a disposal tunnel was confirmed.

WS2-2 スズキ低騒音実車風洞の紹介(1)(自動車に関連する実験計測・数値計算に関するワークショップ,ワークショップ)

WS2-2 スズキ低騒音実車風洞の紹介(1)(自動車に関連する実験計測・数値計算に関するワークショップ,ワークショップ)

Pulsations during large-scale fire tests in the Runehamar tunnel

Four large-scale fire tests have been carried out with heavy goods vehicle (HGV) cargos in the Runehamar tunnel in Norway. During two of the fire tests, large pulsations of the gas flow inside the tunnel were observed. These pulsations were registered only when the measured HRR was higher than 125–135 MW. Two different periods of pulsations were registered, short periods of approximately 4 s and longer periods of approximately 18 s. In the article, the pulsations are presented and explanations are given, using a frequency response analysis based on an impedance approach. Using this approach, the authors were able to find the intrinsic resonances of the system, which were close to the periods of 4 and 18 s found in the experiments. Several factors can affect the pulsations, but the calculations show that the oscillation periods are properties of the system. The analyses show further that at certain frequencies (close to those found during the tests), a small disturbance in the flow can create large amplitudes in the pressure. It is proposed that this phenomenon should be studied in conjunction with future full scale tunnel tests.

Wind Tunnel Boundary Corrections for a Full Scale 1903 Wright Flyer Replica

A panel code is developed in order to assess and correct wind-tunnel boundary interferences during a test of a full-scale reproduction of the 1903 Wright Flyer in the Langley Full-Scale Tunnel (LFST). The LFST is a very large, low-speed wind tunnel with a 3 4-open test section. The principal concerns relating to boundary corrections are the relatively large size of the replica relative to the test-section dimensions, coupled with the lack of modern correction techniques for aeronautical testing in open-jet test sections. The Flyer is represented either by simple lifting surfaces, with the accuracy of the representation validated by direct calculations using the panel code CMARC, or by an array of simple horseshoe vortex singularities. Vortex ring panels are used in the boundary correction code. The solution starts by solving the flow in a closed test section in order to obtain the flow properties on the boundaries. An iterative method, based on the one-step method employed in adaptive wall wind-tunnel work, is then used to adapt the boundary geometry to a constant-pressure condition. Finally the boundary interference is obtained by calculating the velocities induced in the test region by the boundary singularities. Results are presented for different test-section boundary configurations: fully closed, fully open, and 3 4 open. Corrections are compared to calculations using the classical method of images.

Numerical Investigation of Flow and Dust Concentration Distributions in the Work Area of a Mountain Tunnel Currently under Construction

Flow patterns, dust concentration profile, and particle motion in a mountain tunnel under construction were calculated numerically for a full-scale tunnel to evaluate the effectiveness of the planned ventilation system. The influence of ventilation air flow rate, the configuration of air tubes, and an obstacle near the working face were investigated. The trajectories of different size particles were calculated at different wall conditions for deposition. A vortex flow was found to form between the air inlet and the working face for all ventilation types examined. The average dust concentration at a height of 1.5 m, corresponding to the average breathing height of a worker, did not consistently decrease with an increased air flow rate in an injection-suction type system. An optimal air flow rate for minimizing the dust concentration may exist. A vortex flow developed around an obstacle near the working face, leading to an increase in dust concentration between the obstacle and the working face. The concentration of dust near the working face was extremely high and was too spatially variable to be accurately described by the average dust concentration in the area between the working face and the air inlet. The fraction of particles removed through the air outlet was dependent on the ventilation pattern, and also decreased with increasing particle size due to immediate deposition of coarse particles on the tunnel floor.

Evaluation of the Wright 1902 Glider Using Full-Scale Wind-Tunnel Data

A reproduction of the Wright 1901 Glider, built by The Wright Experience TM in Warrenton, Virginia, was wind tunnel tested at the Langley Full Scale Tunnel through a range of conditions similar to what was experienced 100 years ago. The testing included a range of dynamic pressures that encompassed the stall and maximum gliding speeds, angles of attack up to 20 ∘ , and sideslip angles of up to 15 ∘ . The results of the test were used to determine not only lift, drag and moment coefficients, but also control power from the actuation of the canard and wing warping controls. A glide ratio measurement of 3.9:1 was recorded and compared to the observations of the Wrights. Simulations of longitudinal and lateral dynamics showed that the aircraft was controllable, although adverse yaw from wing warping caused the aircraft to turn opposite of the commanded roll. Longitudinal stability was found to be a function of angle of attack and the condition of the wing covering, resulting in static margins that varied greatly.

Numerical approach for design of tunnel concrete lining considering effect of fiber reinforcements

Concrete lining is usually installed onto shotcrete and steel support in the road tunnels constructed by NATM for the purpose of improvement of the safety factor for unknown phenomena, interior finishing, prevention of water leakage and so on. In a road tunnel with two lanes in Japan, unreinforced concrete lining with a thickness of 30 cm are generally installed regardless of ground condition. These specifications such as thickness, material have not been determined by the calculation, but on the basis of the previous experience. However, recently the occurrence of many cracks on tunnel lining has been found in some road tunnels, and falling of concrete flakes off tunnel lining has become a serious social issue. The prevention of occurrence of cracks on tunnel lining is urgently necessary. One of the solutions to these problems lies in designing tunnel lining theoretically considering the load-carrying capacity of concrete lining and load acting on lining. In the first part of this paper, model experiments using full-scale tunnel concrete lining specimens as shown in Fig. 1 were carried out to clarify the mechanism of collapse of tunnel lining under various kinds of load conditions and the effect of fiber reinforcements. In the second, in order to establish the numerical analysis method that is able to estimate the load-carrying capacity of the tunnel lining and the effect of fiber reinforcements, numerical analysis using FEM considering the development of cracks were carried out and the results were compared with experimental results. Finally, the load-carrying capacity of concrete lining under assumed load conditions and the condition where fiber reinforcements is effective were investigated by FEM analysis through case studies using an actual tunnel figures. The main conclusions obtained from the study are as follows: (1) The structural load-carrying capacity is governed by the sectional failure due to the compressive failure at two more sections and the steel fiber-reinforced concrete (SFRC) has little effect of improving the structural load-carrying capacity under the load condition that the axial force is dominant comparing with that of bending moment. The structural load-carrying capacity is governed by the development of cracks to a certain extent and the SFRC has the effect of improving the structural load-carrying capacity under the loading condition that the bending moment is dominant. (2) FEM analysis considering the occurrence and development of cracks is effective in estimating the load-carrying capacity of tunnel concrete lining and the effect of steel fiber reinforcements. (3) The high-strength concrete rather than the SFRC has the effect of improving the load-carrying capacity of the concrete lining in the case where the tunnel lining is constrained by the soil mass and distributed load act on the whole concrete lining. (A). Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.

Vortex-induced vibrations of the Second Severn Crossing cable-stayed bridge: full-scale and wind tunnel measurements

Vortex-induced vibrations of the Second Severn Crossing cable-stayed bridge: full-scale and wind tunnel measurements

On the determination of the aerodynamic coefficients of highway tunnels

The determination of the aerodynamic coefficients of highway tunnels is crucial to set up an accurate theoretical model of tunnel ventilation. Their appropriate values vary with situations, such as traffic conditions, auxiliary facilities in tunnel, jet fan performance, and so on, and accordingly shall be determined in real situations. More importantly, their inherent situation-dependent characteristics shall be reflected in the model by using relevant aerodynamics and traffic data obtained by in situ measurement, instead of just employing the data obtained from reduced-scale experiments done in laboratory or the data obtained from handbooks. In this paper, we propose an optimization approach that can simultaneously determine the four major aerodynamic coefficients of road tunnels: the friction coefficient of tunnel wall, the averaged drag coefficients of small-sized and large-size vehicles, and the pressure-rise coefficient of jet fans. The approach is based on the data of the dynamic traffic as well as of the traffic-induced wind speed measured in the 1.8-km-long highway tunnel—Fu-De Tunnel located in the suburb of Taipei City. Since the measurement is made in a full-scale tunnel operating under various realistic traffic situations and Fu-De Tunnel is typical in the modern design, we believe that the coefficient values determined in this paper can be used directly in other modern highway tunnels and shall be more appropriate than those determined by other traditional ways.

Smoke Propagation in Road Tunnels

In tunnel fires, the most immediate threat to life is not the direct exposure to fire, but smoke inhalation. Efficient control of smoke propagation, therefore, is one of the most important issues in designing tunnel ventilation and a full understanding of the characteristics of smoke propagation in tunnels is a necessity in order to proceed with a successful design. In the present article, we review the progress of research on smoke propagation in tunnels, wherein the tests in full-scale tunnels, the nature of fire, the computational fluid dynamic-field model approach (CFD-FMA), and the Froude number preservation approach (FNPA) are discussed. The gravity current approach (GCA) is also developed to predict the smoke propagation behavior in tunnels and a CFD-FMA example is given from which the features of smoke propagation can be closely examined. The analytical results from FNPA indicate that, in the upstream of fire, the critical ventilation velocity is generally proportional to the one-third power of the heat release rate (HRR); some modifications to this power law are necessary for special cases. In the downstream of fire, the GCA results show that smoke propagates along the tunnel with a constant speed, which is essentially linearly proportional to the ventilation velocity. The numerical results from CFD-FMA determine a safety domain in terms of the ventilation velocity and the HRR of fire. In view of rapidly increasing computational power, the CFD-FMA is becoming a major approach in studying smoke propagation in tunnels, while the GCA and FNPA are useful in engineering design. This review article includes 60 references.

New method for true-triaxial rock testing

Sub-surface structures provide attractive alternatives for storage of explosives and other military hardware. These facilities are commonly constructed at shallow depths where rocks have undergone extensive weathering and the geologic system contains joints and discontinuities. For underground munitions storage structures, risk and performance assessment studies have to be conducted to qualify the site and establish the “clear zone” in case of accidental detonation. At high loading densities, accidental detonation of a munitions storage facility can lead to rupturing of the overburden cover and creation of a hazardous fragment environment. The degree and extent of the “clear zone” is controlled by the overall characteristics of the geologic and engineered systems. Rock joint spacing is considered to be important in prediction of the hazardous range of blast-induced fragments and associated impact energy. A full scale tunnel explosion test was conducted in 1988 in the desert of California. The tunnel was constructed in a weathered, jointed, igneous rock mass with several, well defined discontinuities. The information from the overall characteristics of this tunnel was used to construct five scaled model tunnels, with simulated joints and discontinuities, under physical modeling at 1-g. The loading densities used in two of the model tests were equivalent to that of the full scale event. For the other three tests, loading densities were changed in order to determine the effects of the explosive weight on the jointed rockmass response. The tests reported in this paper are unique in terms of size and simulation method. Five large test beds were constructed in trenches filled with model material simulating the full scale jointed rockmass with through-going discontinuities at 20:1 scale. Geometric and strength related properties were scaled, whereas the density scale factors were maintained at unity. The model materials were formulated in such a way that similitude conditions between the properties of the full scale rock mass were maintained. Test beds were constructed by step-by-step casting of the model materials into the excavated trenches. Impedance characteristics of the model materials were matched with those of the host-ground for realistic simulation of the ground shock propagation. This paper provides a brief discussion on the tests performed and elaborates on the applicability and the economics of the physical modeling for studies related to explosives-underground-structures interaction.

Impact of joints and discontinuities on the blast-response of responding tunnels studied under physical modeling at 1-g

Sub-surface structures provide attractive alternatives for storage of explosives and other military hardware. These facilities are commonly constructed at shallow depths where rocks have undergone extensive weathering and the geologic system contains joints and discontinuities. For underground munitions storage structures, risk and performance assessment studies have to be conducted to qualify the site and establish the “clear zone” in case of accidental detonation. At high loading densities, accidental detonation of a munitions storage facility can lead to rupturing of the overburden cover and creation of a hazardous fragment environment. The degree and extent of the “clear zone” is controlled by the overall characteristics of the geologic and engineered systems. Rock joint spacing is considered to be important in prediction of the hazardous range of blast-induced fragments and associated impact energy. A full scale tunnel explosion test was conducted in 1988 in the desert of California. The tunnel was constructed in a weathered, jointed, igneous rock mass with several, well defined discontinuities. The information from the overall characteristics of this tunnel was used to construct five scaled model tunnels, with simulated joints and discontinuities, under physical modeling at 1-g. The loading densities used in two of the model tests were equivalent to that of the full scale event. For the other three tests, loading densities were changed in order to determine the effects of the explosive weight on the jointed rockmass response. The tests reported in this paper are unique in terms of size and simulation method. Five large test beds were constructed in trenches filled with model material simulating the full scale jointed rockmass with through-going discontinuities at 20:1 scale. Geometric and strength related properties were scaled, whereas the density scale factors were maintained at unity. The model materials were formulated in such a way that similitude conditions between the properties of the full scale rock mass were maintained. Test beds were constructed by step-by-step casting of the model materials into the excavated trenches. Impedance characteristics of the model materials were matched with those of the host-ground for realistic simulation of the ground shock propagation. This paper provides a brief discussion on the tests performed and elaborates on the applicability and the economics of the physical modeling for studies related to explosives-underground-structures interaction.

Full scale testing of steel arch tunnel supports

The results of a testing program comprising five full scale tunnel steel arch supports are reported. The arches, made from RSJ, were tested by jacking the arch legs against blocking points located along the crown of the arch. The number as well as the positions of the blocking points were varied in an effort to simulate various roof loading conditions and constraints. A nonlinear finite element modelling technique was applied to simulate the tested arch supports. Comparison of the ultimate strengths obtained from numerical predictions and experimental results show good agreement. It is found from both the experimental and the numerical modelling work carried out that increasing the number of blocking points causes a substantial gain in the load carrying capacity of the arch support.

Transient Three-Dimensional Fire-Induced Air Flow in a Full Scale Ventilated Tunnel

Abstract A modified three-dimensional version of the turbulence k—∊ model is applied to simulate the transient fire-induced air flow and smoke movement in a full scale ventilated tunnel. The mode! adopts the general curvilinear coordinate system to preserve the actual geometry of the tunnel. A modified elliptic grid generation method is introduced to specify all of the boundaries in terms of grid distribution, grid size and angle of intersection. The effects of the buoyancy and mean streamline curvature on turbulence are accounted for in the model. The smoke concentration is expressed in terms of smoke obscuration and is calculated by a conservation equation. The QUICK discretization scheme is used. The predictions are shown to be in reasonable agreement with reported experiment data. Application of the mixed convection parameter Gr∗/Re5/2 H has been extended and this is confirmed by the observed temperature stratification of the heated air flow in the full scale tunnel.

Automatic collection of operational data in underground construction

A tunnel operations analýser (TOA) is a new, high-technology instrument for use in underground work. By remotely sensing the acoustic emissions from operating machines and processes in a tunnel or shaft, and by applying sophisticated computer processing to them, individual process cycles and other detailed information can be collected. Detailed analyses and dissections of the work in progress can be made, and a variety of action-oriented management reports produced. The process is fully automatic. Results of applying this device to three full-scale tunnel projects are presented; the hardware and software that the instrument comprises are discussed in detail; and the process by which this device can be used to reduce tunnel costs substantially are presented. The authors conclude that this type of technology has great potential in tunnelling and other underground work. Un analyseur d'opérations tunneliéres (TOA) est un nouveau instrument de haute technologie á usage sous terre. En déterminant les émissions acoustiques á distance des machines en marche et des opérations en cours dans un tunnel ou dans un puit, et en appliquant un passage sophistiqué á l'ordinateur, des cycles d'opération ainsi que d'autre informations détaillées peuvent être assemblés. Des analyses détaillées et des dissections du travail en cours peuvent être faites, et une collection de rapports pour la direction générale des travaux peut être produite. Le procédé est complétement automatique. Les résultats de l'utilisation de cet appareil á trois projets entiers sont présentés, la machinerie et le logiciel que cet instrument prend en compte sont discutés en détail, et les moyens d'utilisation de cet instrument pour une réduction importante du coût d'un tunnel sont présentés. Les auteurs concluent que ce genre de technologie a un grand potentiel pour les tunnels et autres travaux sous-terrains.

Telecommunications cable combustion characteristics in tunnels.

In order to study telecommunications cable combustion characteristics, a 100m long, ventilated full-scale tunnel was constructed to facilitate measurement of the temperatures inside the tunnel and those of its wall as well the velocities of two-layer countercurrents. Experimental results showed that the temperature distribution along the length of the tunnel was linear on logarithmic temperature. More than 80% of the dissipated calories obtained from the results were seen to be absorbed into the tunnel wall, and over 10% of the dissipated calories escaped as a gas flow out of the tunnel.It was further found that a great volume of ethylene gas, which was generated from polyethylene cable sheath by heat decomposition, was included in the flow of the fire products. This gas did not burn because air-inflow from the tunnel fan was observed to be limited. Measured temperatures inside the tunnel indicated that polyethylene ignition point temperatures were never exceeded beyond about 40m downstream of the burned end of the cables. A 40m long fire-proof cable compartment design was evaluated and found to be effective in stopping the fire spread along an unenclosed upstream segment of cable bundle.

Penetration of retrorocket exhausts into subsonic counterflows.

Simulation experiments were performed in the NASA Langley Full Scale Tunnel to investigate the retroplume heating rates encountered by a lander vehicle during a terminal descent to a planetary surface. A 10% scale model of the Viking Lander with freestream velocity conditions from 37 to 75 ft/sec was used for simulation. The simulation test data were close to the theoretical predictions of Hill et al. (1971).

Span Load Distribution on a Tapered Wing as Affected by Partial-Span Flaps from Tests in the Full-Scale Tunnel

Span Load Distribution on a Tapered Wing as Affected by Partial-Span Flaps from Tests in the Full-Scale Tunnel

Wind Tunnels for Aeronautical Research

THE Aeronautical Research Committee's “Reports and Memoranda No. 1569” (H.M. Stationery Office. 1s. net), recently issued, gives a description of the new open jet wind tunnel at the National Physical Laboratory, and also describes the preliminary model experiments carried out in order to ensure the most efficient aerodynamic performance from the actual tunnel. The results are a striking vindication of the exponents of the use of the principles of dynamical similarity in comparing the behaviour of objects of similar form but varying sizes. These principles offer a convenient, and often the only possible, way of investigating questions in aircraft design and aerodynamic problems generally. Two model tunnels were made, the second based upon experience with the first—and also the compressed air tunnel—in matters of the shape of the ducts, shape and positions of guide vanes at the corners, design of air screws, etc. The power factor of the models was subject to a large scale effect. At the jet speed mainly used during the experimental work, namely, 50 ft./sec., the power factor was 1-8. The variation with Reynolds's number indicated that a full-scale power factor of about 2-6 might be expected. The full-scale tunnel now completed has exactly equalled expectations. The distribution of velocity in the jet is as good as was anticipated, and the power factor has the predicted value of 2-6. The elliptical nozzle of the tunnel has a horizontal major axis measuring 9 ft. 1J in., and a minor axis of 7 ft. 0 in and an input of 375 B.Ht.p. at the airscrew yields an airspeed of about 210 ft./sec. in the jet. The final model is being used for further small-scale research.

The Spinning of Aeroplanes

We should like to preface our essay on the subject of spinning by mentioning the circumstances under which our investigations were carried out and the sources of our information. The Panel of the Aeronautical Research Committee which has been appointed to deal with all questions connected with the stability and control of aeroplanes was requested in 1924 to consider the urgent problems connected with the alarming accidents due to certain machines failing to retover from a spin. After the issue of a preliminary report on the situation by the Panel, the writers of this paper were asked to go into the whole question as far as existing information from full-scale and wind tunnel experiments would permit. We have had ready access to all available data, coming chiefly from Farnborough on the full-scale side, and from the N.P.L. on the model side.