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1
Makoto, Yamaguchi, Kiwata Takahiro, Kono Takaaki e Ueno Toshiyuki. "1192 WATER TUNNEL EXPERIMENTS ON TRANSVERSE VIBRATION OF A CANTILEVERED PRISM". Proceedings of the International Conference on Jets, Wakes and Separated Flows (ICJWSF) 2013.4 (2013): _1192–1_—_1192–6_. http://dx.doi.org/10.1299/jsmeicjwsf.2013.4._1192-1_.
2
Cutler, Paul M. "Modelling the evolution of subglacial tunnels due to varying water input". Journal of Glaciology 44, n. 148 (1998): 485–97. http://dx.doi.org/10.3189/s002214300000201x.
Abstract (sommario):
AbstractThe time evolution of a subglacial tunnel cross-section is examined usine a two-dimensional finite-element ice-flow model coupled to an idealized drainage system. Simulations are driven by physically based calculations of surface water-input variations at Slorgiaciaren, Sweden. Highlights of the model are its ability to handle unsteady conditions and irregular tunnel shapes. Agreement between modelled water pressure and borehole water levels is good. The following conclusions are reached: (i) Tunnels adapt to fluctuating inflow on time-scales of days. Storms, during which effective pressure ranges from 0 to 0.9 MPa, cause significant adjustments but daily fluctuations due solely to melt-water inflow are minor, (ii) Open-channel flow may become commonplace late in the ablation season, (iii) Initial tunnel shape influences subsequent tunnel evolution and seasonal water-pressure variation. Over the course of a summer, tunnels retain some of their initial shape, though in all experiments the width-to-height ratio increased with time, (iv) Tunnel contraction forms broad low tunnels. However, (v) given two tunnels of equal initial area, the higher narrower one expands more rapidly. Thus, more semi-circular tunnels may capture How from broader neighbours early in the summer.
3
Cutler, Paul M. "Modelling the evolution of subglacial tunnels due to varying water input". Journal of Glaciology 44, n. 148 (1998): 485–97. http://dx.doi.org/10.1017/s002214300000201x.
Abstract (sommario):
AbstractThe time evolution of a subglacial tunnel cross-section is examined usine a two-dimensional finite-element ice-flow model coupled to an idealized drainage system. Simulations are driven by physically based calculations of surface water-input variations at Slorgiaciaren, Sweden. Highlights of the model are its ability to handle unsteady conditions and irregular tunnel shapes. Agreement between modelled water pressure and borehole water levels is good. The following conclusions are reached: (i) Tunnels adapt to fluctuating inflow on time-scales of days. Storms, during which effective pressure ranges from 0 to 0.9 MPa, cause significant adjustments but daily fluctuations due solely to melt-water inflow are minor, (ii) Open-channel flow may become commonplace late in the ablation season, (iii) Initial tunnel shape influences subsequent tunnel evolution and seasonal water-pressure variation. Over the course of a summer, tunnels retain some of their initial shape, though in all experiments the width-to-height ratio increased with time, (iv) Tunnel contraction forms broad low tunnels. However, (v) given two tunnels of equal initial area, the higher narrower one expands more rapidly. Thus, more semi-circular tunnels may capture How from broader neighbours early in the summer.
4
GONZALEZ-RODRIGUEZ, DAVID, e OLE SECHER MADSEN. "Boundary-layer hydrodynamics and bedload sediment transport in oscillating water tunnels". Journal of Fluid Mechanics 667 (1 novembre 2010): 48–84. http://dx.doi.org/10.1017/s0022112010004337.
Abstract (sommario):
Oscillating water tunnels are experimental facilities commonly used in coastal engineering research. They are intended to reproduce near-bed hydrodynamic and sediment transport phenomena at a realistic scale. In an oscillating water tunnel, a piston generates an oscillatory motion that propagates almost instantaneously to the whole tunnel; consequently, flow is uniform along the tunnel, unlike the propagating wave motion in the sea or in a wave flume. This results in subtle differences between the boundary-layer hydrodynamics of an oscillating water tunnel and of a propagating wave, which may have a significant effect in the resulting sediment transport. In this paper, we present a zeroth-order analytical model of the turbulent boundary-layer hydrodynamics in an oscillating water tunnel. By using a time-varying eddy viscosity and by accounting for the constraints arising from the tunnel's geometry, the model predicts the oscillating water tunnel hydrodynamics and yields analytical expressions to compute bed shear stresses for asymmetric and skewed waves, both in the absence or presence of an imposed current. These expressions are applied to successfully quantify bedload sediment transport in oscillating water tunnel experiments.
5
Aziz, Fahrurrozi, Katrine A. Stewart e Sylvie Jenni. "Early Growth of Muskmelon in Mulched Minitunnels Containing a Thermal Water Tube. I. Carbon Dioxide Concentrations in the Tunnel". Journal of the American Society for Horticultural Science 126, n. 6 (novembre 2001): 757–63. http://dx.doi.org/10.21273/jashs.126.6.757.
Abstract (sommario):
Temperature modification is the most investigated environmental factor considered to affect muskmelon (Cucumis melo L. Reticulatus Group) growth in a mulched minitunnel production system. Until now, effects on CO2 concentrations within the tunnel have been ignored. Experiments on production of `Earligold' netted muskmelon were conducted in 1997, 1998, and 1999 to determine daily CO2 concentrations for 10 mulched minitunnel and thermal water tube combinations. Carbon dioxide concentrations under nonperforated (clear or infrared-blocking polyethylene) tunnels were significantly higher (three to four times) than that of ambient air. Soil respiration under the plastic mulch was primarily responsible for increased CO2 levels in the tunnel. Daily CO2 concentrations in the tunnels varied little during early muskmelon growth, but fluctuated widely as the plants developed. Ventilation significantly decreased CO2 concentrations in the tunnels but levels remained significantly above the control and perforated tunnel treatments. When using mulched minitunnels for muskmelon production, daily CO2 concentrations should be recognized as a significant factor influencing growth.
6
Huang, Zhangkai, Meixia Chen, Ting Wang, Huachang Cui e Wenkai Dong. "Numerical Investigation of Background Noise in a Circulating Water Tunnel". Machines 11, n. 8 (18 agosto 2023): 839. http://dx.doi.org/10.3390/machines11080839.
Abstract (sommario):
The presence of excessive background noise in hydrodynamic noise experiments conducted in circulating water tunnels can significantly impact the accuracy and reliability of experimental test results. To address this issue, it is crucial to evaluate and optimize the background noise during the design stage. In this research, acoustic field model and fluid–solid coupling numerical calculation model of circulating water tunnels are established. Utilizing the finite element method, we analyze the flow noise and flow-excited noise resulting from wall pressure pulses in the circulating water tunnel. Furthermore, we conduct a noise contribution analysis and explore strategies for structural vibration noise control. The results demonstrate that both flow noise and flow-excited noise decrease with increasing frequency, with flow-excited noise being the primary component of the tunnel’s background noise. The presence of resonant peaks significantly contributes to the elevated flow-excited noise levels. Moreover, enhancing structural stiffness and damping proves less effective in suppressing low-frequency peaks. Additionally, employing sound measurement pods suspended from the side of the test section for noise measurement exhibits a high error rate at low frequencies. This research provides insights into optimizing background noise in water tunnels, thereby informing future enhancements in tunnel design.
7
Kerwin, Justin E. "The MIT Marine Hydrodynamics Water Tunnel—A 53rd Anniversary Celebration". Marine Technology and SNAME News 31, n. 03 (1 luglio 1994): 183–94. http://dx.doi.org/10.5957/mt1.1994.31.3.183.
Abstract (sommario):
Fifty-three years ago, Professor Frank M. Lewis presented a paper entitled "Propeller Testing Tunnel at the Massachusetts Institute of Technology," at the spring meeting of SNAME. The tunnel is still there, although its name is changed, and its appearance2 is very different. However, the goals of the laboratory are still very much the same—to conduct innovative experiments designed to learn more about the fundamentals of the flow around propellers and other objects of interest to ocean engineers. This paper presents a historical review of many of the varied experiments conducted since the tunnel was completed, with emphasis on several recent projects. This will include an account of the application of the Laser Doppler Velocimeter to map the flow around propellers, underwater vehicles and cavitating foil sections, as well as the development of an apparatus to study the response of a two-dimensional foil to high-frequency gusts. The combination of experiments and theory is discussed, and some thoughts on future experiments are presented.
8
Bao, Tong, Sulei Zhang, Chang Liu e Qing Xu. "Experimental Study on the Effect of Hydraulic Deterioration of Different Drainage Systems on Lining Water Pressure". Processes 10, n. 10 (30 settembre 2022): 1975. http://dx.doi.org/10.3390/pr10101975.
Abstract (sommario):
With the increasing operation time of tunnels, the drainage system cannot fulfil its proper function as a result of the deterioration of traditional waterproof and drainage systems (TWDS), such as the blockage of drainage blind pipes and the failure of drainage boards. Therefore, the lining bears a high water pressure and even causes disasters such as tunnel leakage and lining cracking. An effective solution to mitigate these issues is to adjust the tunnel drainage scheme. In view of this, a composite waterproof and drainage system (CWDS) is proposed in this paper. To verify the effectiveness of the proposed system, a series of model experiments were conducted to study the change law of the seepage field of two drainage systems under different blockage conditions. The study results showed that longitudinal blind pipe blockage caused a more significant increase in water pressure than circular blind pipe blockage. In the case of blind pipe blockage, the water pressure of the TWDS tunnels rise rapidly, while the CWDS tunnels could effectively drain and reduce pressure.
9
Machado Jorge, Vitor Augusto, Pedro Daniel de Cerqueira Gava, Juan Ramon Belchior de França Silva, Thais Mancilha, Waldir Vieira, Geraldo José Adabo e Cairo Lúcio Nascimento. "Analytical Approach to Sampling Estimation of Underwater Tunnels Using Mechanical Profiling Sonars". Sensors 21, n. 5 (9 marzo 2021): 1900. http://dx.doi.org/10.3390/s21051900.
Abstract (sommario):
Hydroelectric power plants often make use of tunnels to redirect the flow of water to the plant power house. Such tunnels are often flooded and can span considerable distances. Periodical inspections of such tunnels are highly desirable since a tunnel collapse will be catastrophic, disrupting the power plant operation. In many cases, the use of Unmanned Underwater Vehicles (UUVs) equipped with mechanical profiling sonars is a suitable and affordable way to gather data to generate 3D mapping of flooded tunnels. In this paper, we study the resolution of 3D tunnel maps generated by one or more mechanical profiling sonars working in tandem, considering synchronization and occlusion problems. The article derives the analytical equations to estimate the sampling of the underwater tunnels using mechanical profiling sonars (scanning sonars). Experiments in a simulated environment using up to four sensors simultaneously are presented. We also report experimental results obtained by a UUV inside a large power plant tunnel, together with a first map of this environment using a single sonar sensor.
10
Lai, Leyi, Yuanzhu Zhang e Kuixin Xu. "Prediction of Wet Area of Underwater Tunnel Lining". Buildings 14, n. 2 (2 febbraio 2024): 408. http://dx.doi.org/10.3390/buildings14020408.
Abstract (sommario):
The issue of water seepage poses a significant challenge in tunnel infrastructure. Wet areas are commonly used to evaluate the degree of water seepage in tunnel projects. To investigate the feasibility for numerical simulation to predict a wet area, we selected concrete test blocks with two types of defects—holes and cracks—as the research specimens. Numerical models for various seepage conditions were constructed using TOUGH2, and the results were validated through laboratory experiments. Additionally, the Shenjiamen Subsea Tunnel was simplified into a numerical model, employing TOUGH2 to forecast its future wet area performance within the scope of national standards. The outcomes of our research revealed that point seepage and line seepage exhibited circular and elliptical morphologies, respectively. Moreover, external water pressure and defect size exerted a significant influence on the expansion of the wet area. Notably, the impact of crack width surpassed that of hole diameter. Encouragingly, the numerical models generated using TOUGH2 for unsaturated concrete demonstrated excellent agreement with laboratory test results concerning the geometry, size, and pattern of the wet area. These findings signified the potential of TOUGH2 numerical simulation as a valuable tool in predicting the lifespan of tunnels.
11
Zhao, Shuanfeng, Bo Liu, Bowen Ren, Li Wang, Zhijian Luo, Jian Yao e Yunrui Bai. "Three-Dimensional ERT Advanced Detection Method with Source-Position Electrode Excitation for Tunnel-Boring Machines". Sensors 24, n. 10 (18 maggio 2024): 3213. http://dx.doi.org/10.3390/s24103213.
Abstract (sommario):
Tunnel-boring machines (TBMs) are widely used in urban underground tunnel construction due to their fast and efficient features. However, shield-tunnel construction faces increasingly complex geological environments and may encounter geological hazards such as faults, fracture zones, water surges, and collapses, which can cause significant property damage and casualties. Existing geophysical methods are subject to many limitations in the shield-tunnel environment, where the detection space is extremely small, and a variety of advanced detection methods are unable to meet the required detection requirements. Therefore, it is crucial to accurately detect the geological conditions in front of the tunnel face in real time during the tunnel boring process of TBM tunnels. In this paper, a 3D-ERT advanced detection method using source-position electrode excitation is proposed. First, a source-position electrode array integrated into the TBM cutterhead is designed for the shield-tunnel construction environment, which provides data security for the inverse imaging of the anomalous bodies. Secondly, a 3D finite element tunnel model containing high- and low-resistance anomalous bodies is established, and the GREIT reconstruction algorithm is utilized to reconstruct 3D images of the anomalous body in front of the tunnel face. Finally, a physical simulation experiment platform is built, and the effectiveness of the method is verified by laboratory physical modeling experiments with two different anomalous bodies. The results show that the position and shape of the anomalous body in front of the tunnel face can be well reconstructed, and the method provides a new idea for the continuous detection of shield construction tunnels with boring.
12
Hynninen, Antti, Ville Viitanen, Jukka Tanttari, Rhena Klose, Claudio Testa e Jussi Martio. "Multiphase Flow Simulation of ITTC Standard Cavitator for Underwater Radiated Noise Prediction". Journal of Marine Science and Engineering 11, n. 4 (12 aprile 2023): 820. http://dx.doi.org/10.3390/jmse11040820.
Abstract (sommario):
This work focuses on the main issues related to noise measurements in cavitation tunnels. The scope of the paper is to twofold: to obtain a better understanding on the main phenomena underlying experiments and to define consistent cavitation tunnel measurement corrections for background noise, wall reflections, and distance normalisation. To this aim, the acoustic field generated by the ITTC standard cavitator model inside a cavitation tunnel is predicted by Lighthill’s acoustic analogy and solved through a finite element method that inherently accounts for the presence of the walls. Sources of sound detection relies on two multiphase CFD solvers, namely, the homogeneous mixture model—Volume of Fluid method and the Euler–Euler formulations. Starting from the computation of the sound pressure level in the free field with the assumption of spherical spreading without absorption, corrections from losses and spreading are detected by the above approach. Background-corrected sound pressure levels are identified and then compared with the source levels measured in the cavitation tunnel of the Potsdam Model Basin (SVA). It is found that free-field computations corrected by tunnel-induced effects match well with experiments up to 100 Hz (in the one-third octave band), whereas relevant discrepancies arise out of this range that need further investigations.
13
Manovski, P., P. Gulotta, C. M. de Silva, R. Brown, M. Giacobello, N. Hutchins e I. Marusic. "Particle tracer analysis for PIV experiments in a closed loop transonic wind tunnel". Proceedings of the International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics 20 (11 luglio 2022): 1–22. http://dx.doi.org/10.55037/lxlaser.20th.225.
Abstract (sommario):
A performance study of several tracer particles for PIV has been conducted. The study included particle response time analysis of an oblique shock wave generated by a conical nose of a store model in a closed loop transonic wind tunnel, and in-situ measurements of the particle size distribution in a low-speed wind tunnel facility. From the oblique shock wave analysis, the estimated particle response time for different smoke materials and generator settings was of the order of 1.4 - 2.2 μs and the effective particle size was 0.58 - 0.85 μm, which was much larger than the measured geometric mean particle size. This larger size was mainly attributed to the correlation bias towards larger particles in PIV measurements. The effective particle size from the particle response time analysis accounts for the holistic performance of the PIV system. Additionally, particle response analysis was performed on ambient water droplets resident in the tunnel. The estimated particle response time for the water droplets was in the order of 3.4 μs and the effective particle size was 0.97 μm, revealing inferior performance compared to the smoke particles.
14
Lin, C. N., Yu Yong Jiao e Q. S. Liu. "Site Experiment for Predicting Hazardous Geological Formations ahead of Tunnel Face". Key Engineering Materials 326-328 (dicembre 2006): 461–64. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.461.
Abstract (sommario):
In the construction of railways in western part of China, more and more long tunnels have been excavated these years, and several ones are under construction at the moment. Because of the complex geologies like faults, fractured zones, karst cavities as well as water bearing formations, the stability and safety of tunnels have been challenging topics in the construction process. In this regard, the advance knowledge of the location, size, and spatial information of the uncertainties ahead of the face is very important to the contractors. In this paper, by using the Tunneling Seismic Prediction (TSP) technique, site experiments are performed to predict hazardous formations ahead of face in a railway tunnel. Through interpretation of the testing data, the wave velocities and the mechanical parameters of the surrounding rock are obtained, and the faults/fractures are recognized. The study shows that compared to time-consuming core drilling method, the wave reflection based TSP method can predict major uncertain formations in long range ahead of the face in short time. The downtime, as we know, is one of the key factors in speeding the tunnel construction. For the prediction accuracy, the TSP technique is able to provide enough information due to its multiple proof-test procedure.
15
Jian, Liu, He Na, Yin Wen Wu e Liu Jin. "Water Jet Vacuum Dust Suppression Device Used to Tunnel Development". Advanced Materials Research 594-597 (novembre 2012): 1188–92. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1188.
Abstract (sommario):
At present domestic tunnel construction, dust is one of the main factors which impact the production efficiency, safety clean production. It not only pollutes the environment, but also threats the health of workers. This article start from the tunnel dust prevention, control measures, heading face negative pressure control dust, and spray jet with the dust, to do research about the mineral water jet dust negative pressure technology. Combining experiments and field test methods, Study the dust fall mechanism of the tunnel water jet vacuum dust suppression, the device parameters and the effect of dust, the application of the technology has great significance to reduce the dust concentration of tunneling face and improve the working environment of workers.
16
Liu, Yuanming, Chen Peng, Qiaowei Yuan e Huiyu Chen. "Chemical Evolution Process and Quality Assessment of Seepage Groundwater in Tunnel Crossing Gas-Bearing Coal Seams". Geofluids 2022 (16 maggio 2022): 1–20. http://dx.doi.org/10.1155/2022/8524932.
Abstract (sommario):
The chemical characteristics of groundwater in the gas coal seam section of the tunnel have rich geological significance. To study the chemical evolution process and controlling factors of groundwater in the gas-bearing coal seam section of the tunnel, and the influence of tunnel coal removal on the groundwater quality, field investigations and laboratory experiments were carried out on the groundwater in the coal measure strata and the high-gaseous section and surrounding aquifers. Through hydrochemical analysis, correlation analysis, hydrochemical simulation, and other methods, the chemical origin of groundwater in coal measure strata and other aquifers was revealed. The water quality of groundwater was analyzed by water quality index (WQI), sodium adsorption rate (SAR), percentage of soluble sodium (Na+%), and participation of sodium carbonate (RSC). The results show that the water samples of each aquifer are weakly alkaline. Influenced by formation lithology and mineral redox reactions, the genesis of coal formation water is more complex than that of natural karst groundwater. The water chemistry characteristics show obvious differences among aquifer groups, with low correlation of HCO3-, Ca2+, and Mg2+. The central drainage ditch is dominated by dolomite dissolution, and the sloping shaft side ditch is dominated by calcite dissolution, and ion exchange effects are prevalent in different water sources. In terms of irrigation water quality, the permeability index (PI), magnesium hazard (MH), and Kelly index (KI) calculations show that 45.8% of the water samples are in the “unsuitable” condition. This study helps to fully understand the quality of coal seam water in tunnels and can provide a reference for groundwater utilization.
17
Li, Shuai, Jianmin Zhang, Xiaoqing Chen, Gordon G. D. Zhou e Jiangang Chen. "Characteristics of aeration in the flow downstream of a radial gate with a sudden fall-expansion aerator in a discharge tunnel". Water Supply 18, n. 3 (25 luglio 2017): 790–98. http://dx.doi.org/10.2166/ws.2017.155.
Abstract (sommario):
Abstract The mechanisms of cavitation damage in flood releasing tunnels remain unclear. In this study a series of physical experiments and numerical calculations were conducted to investigate the flow pattern, pressure distribution and cavitation downstream of a sudden fall-expansion aerator in a discharge tunnel. When the radial gate was partly open, the bottom cavity length reduced drastically, the lateral cavity disappeared, and the flow cavitation index near the sidewalls was less than 0.2. The pressure on the floor and sidewalls can be divided into four regimes: the cavity regime, the impact regime, the reflective regime and the stable regime. The time-average pressure is subject to a unimodal distribution when the gate is fully open, whereas a bimodal distribution is presented when the gate is partly open. The negative pressure regime presented an elliptic shape. Cavitation erosion occurred easily on lateral expansion sidewalls in the tunnel with the radial gate partly open.
18
Dvanajščak, Drago, Jože Ratej e Vojkan Jovičić. "Sustainability of Water Resources in Karst Undermined by Tunneling: A Case Example". Sustainability 14, n. 2 (10 gennaio 2022): 732. http://dx.doi.org/10.3390/su14020732.
Abstract (sommario):
Water resources in karsts are scarce due to the high cavernosity in the otherwise low-permeability limestone rock mass. The highly variable porosity and transmissivity of karst aquifers are caused by a network of channels, caverns, and caves that typically act as water-bearing, connected vessels. Tunneling in a karst environment can severely deplete an aquifer and undermine the sustainability of water resources over the long term. A research study was carried out to elaborate and develop measures for the sustainable preservation of the water resources in a Slovenian karst, in which two approximately 7 km-long tunnels will be driven as part of the construction of the new Divača–Koper railway line. Hydrogeological site investigations were carried out with an aim to evaluate the transmissivity and spatial spreading of the karst aquifer along the route of the tunnels, including the observation of the long-term variation of the groundwater levels and trace experiments. The main findings, which are presented in this paper, were used to develop a methodology for the selection of adequate measures for tunnel construction with an aim of ensuring the sustainability of water resources in karst aquifers. The construction measures comprise limiting the inflows using injection grouting, obscuring the groundwater intake by undrained sections of the tunnel, and constructing bypasses around the tunnel to preserve the current groundwater flow regime. The presented methodology of dynamically accommodating the preventive measures to the actual hydrogeological conditions onsite is generally applicable for common cases in which the state of the karst aquifer could not be pre-determined with a sufficient accuracy of tens of meters to a meter. The spatially and temporally continuous hydrogeological investigations and decision-making charts to reduce the tunnelling’s impact on the karst aquifer are explained in detail in this paper.
19
Wang, Jianxiu, Ansheng Cao, Zhao Wu, Huanran Wang, Xiaotian Liu, Huboqiang Li e Yuanwei Sun. "Experiment and Numerical Simulation on Grouting Reinforcement Parameters of Ultra-Shallow Buried Double-Arch Tunnel". Applied Sciences 11, n. 21 (8 novembre 2021): 10491. http://dx.doi.org/10.3390/app112110491.
Abstract (sommario):
For an ultra-shallow buried double-arch tunnel with a large cross-section, the arching effect is difficult to form in surrounding rock, and grouting method is often adopted to reinforce the surrounding rock. Hence, examining the grouting reinforcement parameters is of great significance for potential failure and collapse prevention. The land part of Haicang undersea tunnel was selected as a case study; laboratory experiments, theoretical analysis, and numerical simulation were performed to determine the grouting solid strength and grouting reinforcement parameters. The effects of different water–cement ratios on slurry fluidity, setting time, bleeding rate, and sample strength were studied by laboratory experiments. A method was proposed to determine the shear strength parameters of grouted surrounding rock through the grout water–cement ratio and the unconfined compressive strength of the rock mass. Numerical simulations were performed for grouting reinforcement layer thickness and the water–cement ratios. The deformation and stability law of tunnel surrounding rock and its influence on surrounding underground pipelines were obtained considering the spatial effect of tunnel excavation and grouting reinforcement. The reasonable selection range of grouting reinforcement parameters was proposed. The initial setting time and bleeding rate of cement slurry increased with the increasing water–cement ratio, while the viscosity of cement slurry and sample strength decreased with the increasing water–cement ratio. The shear strength parameters of grouted surrounding rock were determined by the water–cement ratio of grout and unconfined compressive strength of rock mass before grouting. When the thickness of grouting reinforcement layer h = 1.5 m and the water–cement ratio of grout was suggested η = 0.85, the surface settlement, the deformation of the vault, and the deformation of the nearby pipeline all met the design. Moreover, the construction requirements were more economical. Research results can provide a reference for the selection of grouting reinforcement parameters for similar projects.
20
Johansen, Espen S., e Othon K. Rediniotis. "Unsteady Calibration of Fast-Response Pressure Probes, Part 2: Water-Tunnel Experiments". AIAA Journal 43, n. 4 (aprile 2005): 827–34. http://dx.doi.org/10.2514/1.12355.
21
Bansmer, Stephan E., Arne Baumert, Stephan Sattler, Inken Knop, Delphine Leroy, Alfons Schwarzenboeck, Tina Jurkat-Witschas, Christiane Voigt, Hugo Pervier e Biagio Esposito. "Design, construction and commissioning of the Braunschweig Icing Wind Tunnel". Atmospheric Measurement Techniques 11, n. 6 (6 giugno 2018): 3221–49. http://dx.doi.org/10.5194/amt-11-3221-2018.
Abstract (sommario):
Abstract. Beyond its physical importance in both fundamental and climate research, atmospheric icing is considered as a severe operational condition in many engineering applications like aviation, electrical power transmission and wind-energy production. To reproduce such icing conditions in a laboratory environment, icing wind tunnels are frequently used. In this paper, a comprehensive overview on the design, construction and commissioning of the Braunschweig Icing Wind Tunnel is given. The tunnel features a test section of 0.5 m × 0.5 m with peak velocities of up to 40 m s−1. The static air temperature ranges from −25 to +30 ∘C. Supercooled droplet icing with liquid water contents up to 3 g m−3 can be reproduced. The unique aspect of this facility is the combination of an icing tunnel with a cloud chamber system for making ice particles. These ice particles are more realistic in shape and density than those usually used for mixed phase and ice crystal icing experiments. Ice water contents up to 20 g m−3 can be generated. We further show how current state-of-the-art measurement techniques for particle sizing are performed on ice particles. The data are compared to those of in-flight measurements in mesoscale convective cloud systems in tropical regions. Finally, some applications of the icing wind tunnel are presented.
22
Wang, X., J. Jiang e R. Kaye. "Improvement of a wind-tunnel sampling system for odour and VOCs". Water Science and Technology 44, n. 9 (1 novembre 2001): 71–77. http://dx.doi.org/10.2166/wst.2001.0511.
Abstract (sommario):
Wind-tunnel systems are widely used for collecting odour emission samples from surface area sources. Consequently, a portable wind-tunnel system was developed at the University of New South Wales that was easy to handle and suitable for sampling from liquid surfaces. Development work was undertaken to ensure even air-flows above the emitting surface and to optimise air velocities to simulate real situations. However, recovery efficiencies for emissions have not previously been studied for wind-tunnel systems. A series of experiments was carried out for determining and improving the recovery rate of the wind-tunnel sampling system by using carbon monoxide as a tracer gas. It was observed by mass balance that carbon monoxide recovery rates were initially only 37% to 48% from a simulated surface area emission source. It was therefore apparent that further development work was required to improve recovery efficiencies. By analysing the aerodynamic character of air movement and CO transportation inside the wind-tunnel, it was determined that the apparent poor recoveries resulted from uneven mixing at the sample collection point. A number of modifications were made for the mixing chamber of the wind-tunnel system. A special sampling chamber extension and a sampling manifold with optimally distributed sampling orifices were developed for the wind-tunnel sampling system. The simulation experiments were repeated with the new sampling system. Over a series of experiments, the recovery efficiency of sampling was improved to 83-100% with an average of 90%, where the CO tracer gas was introduced at a single point and 92-102% with an average of 97%, where the CO tracer gas was introduced along a line transverse to the sweep air. The stability and accuracy of the new system were determined statistically and are reported.
23
Su, Haijian, Yujie Feng, Qingzhen Guo, Hongwen Jing e Wenxin Zhu. "Model Experimental Study on the Seepage and Failure Features of Tunnel under Wetting-Drying Alternation with Increasing Water Pressure". Geofluids 2020 (4 luglio 2020): 1–11. http://dx.doi.org/10.1155/2020/8845528.
Abstract (sommario):
Wetting-drying alternation caused by seasonal rainfall and water fluctuation has a negative effect on the rock mass. Model experiments were conducted in this paper to investigate the role of wetting-drying alternation on the seepage and failure features of a tunnel. Water-bearing structure was located in the lateral position of tunnel. The stratum thickness between the tunnel and water-bearing structure was ranged from 20 to 100 mm. The results showed that, with an increase in the wetting-drying alternation number, the pore water pressure increases gradually. The critical water pressure also increases gradually with the increasing thickness of water-resisting stratum. With the increase of the stratum thickness, the permeable area is gradually widened and the water storage capacity becomes stronger. The failure mode of water-resisting stratum under geostress and water pressure can be summarized as two types: fracture failure (thickness of 20 mm) and slippage failure (thickness between 40 and 100 mm), respectively.
24
Aziz, Fahrurrozi, Katrine A. Stewart e Sylvie Jenni. "Early Growth of Muskmelon in Mulched Minitunnels Containing a Thermal Water Tube. II. Air, Soil, and Water Tube Temperatures and Vegetative Growth". Journal of the American Society for Horticultural Science 126, n. 6 (novembre 2001): 764–70. http://dx.doi.org/10.21273/jashs.126.6.764.
Abstract (sommario):
Field experiments were conducted during 1997, 1998, and 1999 to determine effects of 10 combinations of mulched minitunnel and thermal water tube on air, soil, and water-tube temperatures and on vegetative growth of `Earligold' netted muskmelon (Cucumis melo L. Reticulatus Group) within the tunnels. Use of mulched minitunnels significantly increased air, soil and water temperatures during the preanthesis phase in all years compared with control treatments. Inclusion of water tubes and venting the tunnels decreased air temperature fluctuations in the tunnels. During the first 10 to 15 days after transplanting, plants grown in nonperforated tunnels had higher relative growth rates (RGRs), net assimilation rates (NARs), and dry weights (DWs) than those grown under perforated tunnels and control plots. Plants in tunnels containing thermal water tubes generally had higher RGRs, NARs, and DWs than those without tubes. During the later part of the experiment, from 11 to 16 days after transplanting until anthesis, however, there were no consistent effects of mulched minitunnels on RGR, NAR, and plant DW. Tunneled muskmelons had significantly higher RGRs, but generally lower NARs than those grown without tunnel. Use of mulched minitunnels significantly increased plant DW at anthesis in 1997, but not in 1998 and 1999. Plants grown in the minitunnels containing a thermal water tube generally had higher RGRs, NARs, and DWs than those without water tubes. Ventilating nonperforated tunnels generally increased RGR, NAR, and plant DW. Plants grown in the tunnels reached anthesis 10 days earlier than those without tunnels.
25
Zhao, Xin, e Edward E. Carey. "Summer Production of Lettuce, and Microclimate in High Tunnel and Open Field Plots in Kansas". HortTechnology 19, n. 1 (gennaio 2009): 113–19. http://dx.doi.org/10.21273/hortsci.19.1.113.
Abstract (sommario):
High tunnels have been shown to be a profitable season-extending production tool for many horticultural crops. Production of cool-season vegetables during the hot summer months represents a challenge to market growers in the midwestern United States. Two experiments were conducted to investigate the microclimate and production of eight leaf lettuce (Lactuca sativa) cultivars in high tunnels and open fields, using unshaded and shaded (39% white shadecloth) tunnels in Summer 2002 and 2003, respectively. Wind speed was consistently lower in high tunnels with the sidewalls and endwalls open. An unshaded high tunnel resulted in an increase of daily maximum and minimum air temperatures by ≈0.2 and 0.3 °C, respectively, in comparison with the open field. In contrast, daily maximum air temperature in a shaded high tunnel decreased by 0.4 °C, while the daily minimum air temperature was higher than that in the open field by 0.5 °C. Using high tunnels did not cause a marked change in relative humidity compared with the open field. When using shadecloth, the daily maximum soil temperature was lowered by ≈3.4 °C and the leaf surface temperature was reduced by 1.5 to 2.5 °C. The performance of lettuce during summer trials varied significantly among cultivars. Unshaded high tunnels generally led to more rapid bolting and increased bitterness of lettuce compared with the open field. Lettuce grown in high tunnels covered by shadecloth had a lower bolting rate, but decreased yield relative to the open field. Based on our results, summer lettuce production would not be recommended in high tunnels or open fields in northeastern Kansas, although the potential of shaded high tunnels deserves further studies. Reference crop evapotranspiration (ET0) was estimated from meteorological data on a daily basis using the FAO-56 method. The ET0 was lowest in the shaded high tunnel and was the highest in the open field. Relatively lower ET0 in high tunnels indicated a likely lower water requirement and therefore improved water use efficiency compared with the open field.
26
Zhao, Xin, e Edward E. Carey. "Summer Production of Lettuce, and Microclimate in High Tunnel and Open Field Plots in Kansas". HortTechnology 19, n. 1 (gennaio 2009): 113–19. http://dx.doi.org/10.21273/horttech.19.1.113.
Abstract (sommario):
High tunnels have been shown to be a profitable season-extending production tool for many horticultural crops. Production of cool-season vegetables during the hot summer months represents a challenge to market growers in the midwestern United States. Two experiments were conducted to investigate the microclimate and production of eight leaf lettuce (Lactuca sativa) cultivars in high tunnels and open fields, using unshaded and shaded (39% white shadecloth) tunnels in Summer 2002 and 2003, respectively. Wind speed was consistently lower in high tunnels with the sidewalls and endwalls open. An unshaded high tunnel resulted in an increase of daily maximum and minimum air temperatures by ≈0.2 and 0.3 °C, respectively, in comparison with the open field. In contrast, daily maximum air temperature in a shaded high tunnel decreased by 0.4 °C, while the daily minimum air temperature was higher than that in the open field by 0.5 °C. Using high tunnels did not cause a marked change in relative humidity compared with the open field. When using shadecloth, the daily maximum soil temperature was lowered by ≈3.4 °C and the leaf surface temperature was reduced by 1.5 to 2.5 °C. The performance of lettuce during summer trials varied significantly among cultivars. Unshaded high tunnels generally led to more rapid bolting and increased bitterness of lettuce compared with the open field. Lettuce grown in high tunnels covered by shadecloth had a lower bolting rate, but decreased yield relative to the open field. Based on our results, summer lettuce production would not be recommended in high tunnels or open fields in northeastern Kansas, although the potential of shaded high tunnels deserves further studies. Reference crop evapotranspiration (ET0) was estimated from meteorological data on a daily basis using the FAO-56 method. The ET0 was lowest in the shaded high tunnel and was the highest in the open field. Relatively lower ET0 in high tunnels indicated a likely lower water requirement and therefore improved water use efficiency compared with the open field.
27
Zhang, Yuanzhu, Xiaozhen Li e Guohua Yu. "Chloride Transport in Undersea Concrete Tunnel". Advances in Materials Science and Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/1085934.
Abstract (sommario):
Based on water penetration in unsaturated concrete of underwater tunnel, a diffusion-advection theoretical model of chloride in undersea concrete tunnel was proposed. The basic parameters including porosity, saturated hydraulic conductivity, chloride diffusion coefficient, initial water saturation, and moisture retention function of concrete specimens with two water-binder ratios were determined through lab-scale experiments. The variation of chloride concentration with pressuring time, location, solution concentration, initial saturation, hydraulic pressure, and water-binder ratio was investigated through chloride transport tests under external water pressure. In addition, the change and distribution of chloride concentration of isothermal horizontal flow were numerically analyzed using TOUGH2 software. The results show that chloride transport in unsaturated concrete under external water pressure is a combined effect of diffusion and advection instead of diffusion. Chloride concentration increased with increasing solution concentration for diffusion and increased with an increase in water pressure and a decrease in initial saturation for advection. The dominant driving force converted with time and saturation. When predicting the service life of undersea concrete tunnel, it is suggested that advection is taken into consideration; otherwise the durability tends to be unsafe.
28
Bussink, D. W., J. F. M. Huijsmans e J. J. M. H. Ketelaars. "Ammonia volatilization from nitric-acid-treated cattle slurry surface applied to grassland". Netherlands Journal of Agricultural Science 42, n. 4 (1 dicembre 1994): 293–309. http://dx.doi.org/10.18174/njas.v42i4.590.
Abstract (sommario):
The reduction in NH3 loss from HNO3 treated cattle slurry, surface applied to grassland, was measured on different soil types throughout the Netherlands from 1989 to 1992. Thirteen micro-meteorological mass balance and 10 small wind tunnel experiments were carried out. Amounts varying between 7-17 and 10-30 m-3 ha-1 were applied, resp. and measurements were performed for 4 and 10 days, resp. The pH of treated slurry ranged from 3.9 to 6.6. A mean total of 60% (range: 29-98%) of the NH4-N from untreated slurry was volatilized in the mass balance experiments. A reduction in NH3 volatilization of 85, 72 and 55% was achieved for acidified slurry with a respective pH of c. 4.5, 5.0 and 6.0. Approx 55% (range: 7-91%) of the total loss from acidified slurry was measured on the day of application. A mean total of 66% (range: 21-90%) of NH4-N from untreated slurry volatilized in the tunnel experiments. The reduction in NH3 volatilization was 73% for slurry with pH 4.5. Approx 27% (range: 6-91%) of the total loss from acidified slurry was measured on the first day. The smaller reduction and the different pattern in NH3 volatilization observed in the wind tunnel experiments might be the consequence of different climatic conditions in and outside the tunnels or they might be related to the higher rates of slurry application in these experiments. Regression analysis indicated that high temperature, slurry pH, potential water evaporation and NH4+ concn stimulated NH3 loss in the mass balance experiments (Rsuperscript 2 = 87%). It is suggested that the results obtained with acidified slurry were independent of the grassland soil type at the application levels employed.
29
Yao, Xianchun, Ning Li, Kecheng Wan, Gao Lv e Mingming He. "Experimental and Analytical Study on Mechanical Properties of High Rock Temperature Diversion Tunnel". Advances in Civil Engineering 2019 (3 aprile 2019): 1–11. http://dx.doi.org/10.1155/2019/9537153.
Abstract (sommario):
The high temperature of rock used in different working conditions has a significant effect on the deformation characteristics and the mechanics of tunnel lining support structure. A test using a laboratory model is designed to study the quantitative relationship between the temperature difference and the support force. Through the laboratory model test, the strain and stress variation characteristics of the supporting structure of a water diversion tunnel under different surrounding rock temperatures and different water temperatures were simulated. The variation characteristics of the supporting structure under various working conditions, such as a different initial temperature field, different crossing water temperature of the diversion tunnel during runtime, and repairing period after the water is emptied, were analyzed. The relationship between the high-temperature difference between the inner and outer walls of the tunnel lining support structure and the internal temperature stress of the supporting structure was obtained and compared with the results from numerical experiments. The test results showed that a high circumferential tensile stress is created in the support structure of the high-temperature diversion tunnel due to the temperature difference between the inner and outer walls of the support structure caused by water going through the high-temperature diversion tunnel. The radial compressive stress increases by 45–50%, and the circumferential tensile stress increases by 40–60%. The results provide references for the design of the support structure in a high-temperature tunnel.
30
Cao, Kewang, Furong Dong, Liqiang Ma, Naseer Muhammad Khan, Tariq Feroze, Saad S. Alarifi, Sajjad Hussain e Muhammad Ali. "Infrared Precursor Experiment to Predict Water Inrushes in Underground Spaces Using a Multiparameter Normalization". Sustainability 15, n. 9 (5 maggio 2023): 7570. http://dx.doi.org/10.3390/su15097570.
Abstract (sommario):
Rock failure is the root cause of geological disasters such as slope failure, civil tunnel collapse, and water inrush in roadways and mines. Accurate and effective monitoring of the loaded rock failure process can provide reliable precursor information for water inrushes in underground engineering structures such as in mines, civil tunnels, and subways. The water inrush may affect the safe and efficient execution of these engineering structures. Therefore, it is essential to predict the water inrush effectively. In this paper, the water inrush process of the roadway was simulated by laboratory experiments. The multiparameters such as strain energy field and infrared radiation temperature field were normalized based on the normalization algorithm of linear function transformation. On the basis of analyzing the variation characteristics of the original parameters, the evolution characteristics after the parameters normalization algorithm were studied, and the precursor of roadway water inrush was predicted comprehensively. The results show that the dissipation energy ratio, the infrared radiation variation coefficient (IRVC), the average infrared radiation temperature (AIRT), and the variance of successful minor infrared image temperature (VSMIT) are all suitable for the prediction of roadway water inrushes in the developing face of an excavation. The intermediate mutation of the IRVC can be used as an early precursor of roadway water inrush in the face of an excavation that is being developed. The inflection of the dissipation energy ratio from a declining amount to a level value and the mutation of VSMIT during rock failure can be used as the middle precursor of roadway water inrush. The mutation of AIRT and VSMIT after rock failure can be used as the precursor of roadway imminent water inrush. Combining with the early precursor and middle precursor of roadway water inrush, the graded warning of “early precursor–middle precursor–final precursor” of roadway water inrush can be obtained. The research results provide a theoretical basis for water inrush monitoring and early warning in the sustainable development of mine, tunnel, shaft, and foundation pit excavations.
31
Guo, Qingzhen, Haijian Su, Hongwen Jing e Wenxin Zhu. "Effect of Wetting-Drying Cycle on the Deformation and Seepage Behaviors of Rock Masses around a Tunnel". Geofluids 2020 (26 maggio 2020): 1–14. http://dx.doi.org/10.1155/2020/4237163.
Abstract (sommario):
Water inrush caused by the wetting-drying cycle is a difficult problem in tunnel excavation. To investigate the effect of the wetting-drying cycle on the stability of the tunnel surrounding rock, physical experiments and numerical simulations regarding the process of tunnel excavation with different wetting-drying cycle numbers were performed in this study. The evolutions of stress, displacement, and pore water pressure were analyzed. With the increase in cycle number, the pore water pressure, vertical stress, and top-bottom approach of the tunnel surrounding rock increase gradually. And the increasing process could be divided into three stages: slightly increasing stage, slowly increasing stage, and sharply increasing stage, respectively. The failure process of the surrounding rock under the wetting-drying cycle gradually occurs from the roof to side wall, while the baseplate changes slightly. The simulation results showed that the maximum principal stress in the surrounding rock mass of the tunnel increases, while the minimum principal stress decreases. Furthermore, the displacement of the rock mass decreases gradually with the increasing distance from the tunnel surface. By comparing the simulation results with the experimental results, well consistency is shown. The results in this study can provide helpful references for the safe excavation and scientific design of a tunnel under the wetting-drying cycle.
32
Yang, Jinduo, Xi’an Li, Weiping Wang, Hao Chai, Mingxiao An e Qianyi Dai. "The Mechanism of Dust Transportation Based on Wind Tunnel Experiments and Numerical Simulations". Water 16, n. 7 (29 marzo 2024): 1006. http://dx.doi.org/10.3390/w16071006.
Abstract (sommario):
The process of dust transportation is widespread, leading to the formation of regions such as the Loess Plateau. In order to understand the mechanisms of dust particle transportation, this study conducted wind tunnel experiments to simulate natural wind-driven dust transport processes. Theoretical derivations were carried out to establish the relationship between particle size and transportation distance, which was then validated through numerical simulations. The following conclusions were drawn: (1) wind tunnel experiments, theoretical derivations, and numerical simulations yielded consistent results, indicating the effectiveness of the wind tunnel experiments; (2) Under the influence of wind forces, the ideal transportation distance of particles is inversely proportional to the square of their size; (3) turbulent wind fields have a minor impact on dust transport, while particle roundness has a significant effect on transport; (4) clay particles and dust particles in loess regions share the same source areas and transport pathways.
33
KIWATA, Takahiro, Makoto YAMAGUCHI, Takaaki KONO e Toshiyuki UENO. "Water tunnel experiments on transverse-galloping of cantilevered rectangular and D-section prisms". Journal of Fluid Science and Technology 9, n. 3 (2014): JFST0056. http://dx.doi.org/10.1299/jfst.2014jfst0056.
34
Zhou, Guanqun, Mingxin Yue, Xiaodong Yang, Shengdong Liu, Zhao Wu, Yu Cao e Xiaoping Wu. "A metal interference correction method of tunnel transient electromagnetic advanced detection". Journal of Geophysics and Engineering 17, n. 3 (6 febbraio 2020): 429–38. http://dx.doi.org/10.1093/jge/gxaa002.
Abstract (sommario):
Abstract Water inrush during tunnel excavation severally threatens the mining safety as blind water-bearing structures may develop in front of the working face. The transient electromagnetic method (TEM) has been widely applied in the advanced detection of tunnel water-bearing structures. However, the metal interference of both supports and tools in the tunnel has become a bottleneck that reduces the forecast accuracy of this method. In this paper, we analyse the effect of metal interference on TEM data and propose a novel set of an observation and correction method under metal interference based on the ratio of anomalous and background apparent resistivity. Flume model experiments both with and without metal interference are carried out, showing that this interference can affect TEM measurements significantly and result in false anomalies, and that our proposed method can remove this ambient noise caused by metal interference appropriately. The practical application further proves that this method can effectively reduce low-resistivity interference introduced by the support and other metal tools inside the tunnel. By applying this correction method, the location of water-rich anomalies can be detected more precisely during the excavation process of the same tunnel, which is of high application value of reducing exploration difficulty and tunneling risk.
35
Siwek, Piotr, Iwona Domagała-Świątkiewicz, Andrzej Kalisz e Piotr Bucki. "MICROCLIMATIC CONDITIONS AND PHYSICO-CHEMICAL PROPERTIES OF SOIL IN INTENSIVE ECOLOGICAL VEGETABLE CROP ROTATION IN HIGH TUNNEL". Acta Scientiarum Polonorum Hortorum Cultus 19, n. 3 (29 giugno 2020): 73–81. http://dx.doi.org/10.24326/asphc.2020.3.7.
Abstract (sommario):
In 2014–2015 at the experimental station of the University of Agriculture in Kraków, situated in Mydlniki near Kraków, Poland, experiments with intensive crop rotation in a high tunnel were conducted. The objectives concerned microclimatic zones in the tunnel and the yield and quality of butterhead lettuce (spring), cucumber (summer), and butterhead lettuce (autumn). Besides the properties of the soil in the high tunnel, a crucial role was played by microclimatic factors. The measurements showed variations in solar radiation, temperature and air humidity depending on the zone in the tunnel and the weather. Higher temperature in the centre of the tunnel was conducive to obtaining greater yields of spring lettuce and cucumber. In the spring and summer periods, the amounts of dry matter and total sugars in the edible parts of the cultivated vegetables were higher in the eastern and central zones of the tunnel. In the autumn, with less solar radiation, the amount of sugars in lettuce leaves was greater in the western zone. There was observable influence of the location in the tunnel from which samples were taken for analyses (zonal effect) on some physical parameters of the soil (bulk density, water capacity, and water-stability index).
36
Itagaki, K., G. E. Lemieux e H. W. Bosworth. "Ice Accretion Under Natural and Laboratory Conditions". Annals of Glaciology 6 (1985): 225–28. http://dx.doi.org/10.3189/1985aog6-1-225-228.
Abstract (sommario):
To compare results of icing studies conducted in wind tunnels with natural icing conditions, a series of rotor icing studies were made on top of Mt. Washington, New Hampshire. The results indicated that considerable differences exist between the two under conditions of similar liquid water content and temperature. The wet-to-dry growth transition temperature, for instance, with comparable temperature and liquid water content, may be more than 10°C higher under natural conditions than in wind tunnel studies. The possible cause of such discrepancies was found to be the vapor saturation existing in most laboratory experiments. The transition temperature of ice accretion measured in natural fog on board an aircraft agreed better with the results of the Mt. Washington study.
37
Itagaki, K., G. E. Lemieux e H. W. Bosworth. "Ice Accretion Under Natural and Laboratory Conditions". Annals of Glaciology 6 (1985): 225–28. http://dx.doi.org/10.1017/s0260305500010417.
Abstract (sommario):
To compare results of icing studies conducted in wind tunnels with natural icing conditions, a series of rotor icing studies were made on top of Mt. Washington, New Hampshire. The results indicated that considerable differences exist between the two under conditions of similar liquid water content and temperature. The wet-to-dry growth transition temperature, for instance, with comparable temperature and liquid water content, may be more than 10°C higher under natural conditions than in wind tunnel studies. The possible cause of such discrepancies was found to be the vapor saturation existing in most laboratory experiments. The transition temperature of ice accretion measured in natural fog on board an aircraft agreed better with the results of the Mt. Washington study.
38
Nie, Hong-bin, e Shuan-cheng Gu. "Ultimate Bearing Capacity Analysis of CFRP-Strengthened Shield Segments Using Bonding Slip Behavior Experiments". Materials 13, n. 18 (21 settembre 2020): 4200. http://dx.doi.org/10.3390/ma13184200.
Abstract (sommario):
Shield segments of subway tunnels are often exposed to the combined actions of several hygrothermal factors that could lead to accidents such as water seepage and tunnel collapse. Further, they often break and deform owing to formation pressure. In addition, uncertainties related to the stress relaxation characteristics and bonding performance of carbon-fiber-reinforced plastics (CFRPs) under a hygrothermal environment make their application in subway systems difficult. This study analyzes the effects of the slip-on-bending strength of CFRP-strengthened shield segments in a hygrothermal environment. In the study, the shield segments are damaged at ambient pressure under a combination of humidity (0%, 5%, and 10%) and temperature (20 °C, 25 °C, 30 °C, and 40 °C). An experimental procedure is designed to evaluate a CFRP-reinforced concrete arch. The method predicts the load–slip relationship and maximum shearing stress and strain. Moreover, confined compression tests are conducted on a tunnel segment lining strengthened with CFRP to evaluate the bearing capacity of the CFRP-strengthened shield segments. An equation for the latter’s ultimate bearing capacity is developed based on the elastic layer system theory, stress boundary condition, and bending stress characteristics of axisymmetric elements. It was found that the results from the developed model are compared with the experimental values of CFRP-strengthened shield segments under different humidity values (0%, 5%, and 10%) and a constant temperature. The ultimate strength—the debonding deflection of the CFRP-strengthened shield segment—can be predicted using the proposed ultimate bearing capacity equation with sufficient accuracy.
39
Zhang, Jinliang, Yongchang Li, Yuansheng Zhang, Fengwei Yang, Chao Liang e Shunhui Tan. "Using a high-pressure water jet-assisted tunnel boring machine to break rock". Advances in Mechanical Engineering 12, n. 10 (ottobre 2020): 168781402096229. http://dx.doi.org/10.1177/1687814020962290.
Abstract (sommario):
The concept of tunnel boring machine (TBM) disc cutter rock breaking coupled with high-pressure water jets has been proposed to overcome the difficulties that occur when TBMs encounter extremely hard rocks. Thus, to meet actual engineering requirements for the TBM construction of tunnels as part of the Wan’anxi water diversion project in Longyan City (Fujian Province, China), experiments were conducted on high-pressure water jet-assisted TBM disc cutter rock breaking. By varying kerf depth and width under different water jet parameters and performing disc cutter rock breaking tests on rock surfaces with no kerf, single kerf, and double kerfs, the effects of different kerf depths on the disc cutter rock breaking process, load, and efficiency were examined. The test results showed that high-pressure water jets can generate the regular kerfs required for the coupled disc cutter rock breaking of granite. Employing the coupled rock breaking method also resulted in a decrease in specific energy and an approximately 40% decrease in the normal force of the disc cutter, thereby significantly improving rock breaking efficiency. These results provide key technical parameters for the design and manufacture of high-pressure water jet-assisted rock-breaking TBMs and serves as a reference for similar processes.
40
Fredy Surahmanto, Dipta Adityantoro e Adi Ridwan Satria. "Laboratory-Scale Low-Speed Water Tunnel: Comparison of Experimental Flow Visualization and Computer-Aided Simulation". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 107, n. 1 (31 luglio 2023): 142–64. http://dx.doi.org/10.37934/arfmts.107.1.142164.
Abstract (sommario):
This study aimed at developing the laboratory-scale low-speed water tunnel design by first evaluating the effect of varying the number of wide-angle diffuser vanes and then confirming flow visualization against object geometries tested by experiments and computer-aided simulation. The low-speed water tunnel design in this study consists of a wide-angle diffuser, a honeycomb, a convergent section, and a working section. To ascertain the laminar flow of water would act in the experiment, a prior simulation using 3, 6, and 12 vanes and without a vane was conducted. Some geometries, including tube, triangle, aerofoil, and car models have been tested and then compared to the experimental results. The results indicate that the twelve vanes diffuser is more effective in minimizing turbulent flow and producing a streamlined pattern in the water tunnel. Laminar flow with a Reynolds number of 2238 and flow velocity of 0.008 m/s was obtained in the working section. The flow visualization by experiment and computational fluid dynamics simulation was almost similar.
41
Liu, Qianqian, Yi Zhao e Caixia Liu. "Experimental research on blowing-rain intensity and uniformity of rain tunnel for aircraft rain removal testing". Journal of Physics: Conference Series 2764, n. 1 (1 maggio 2024): 012045. http://dx.doi.org/10.1088/1742-6596/2764/1/012045.
Abstract (sommario):
Abstract The objective of the present study is to characterize a rain tunnel that is used for performance testing of aircraft windshield rain removal systems. The rain tunnel in the present study is an open jet wind tunnel with six full cone pressure swirl nozzles arranged at its outlet. Experiments are conducted with water at room temperature as the working medium. The influence of total water supply flow rate and air velocity on the blowing-rain intensity and uniformity is studied. The total water supply flow rate varies from 0.57 m3/h to 1.03 m3/h, while the pressure at the inlet of the nozzle ranges from 1.44 bar to 6.52 bar. The air velocity of 30 m/s, 40 m/s, and 50 m/s is studied. A special test setup has been designed for measurements of the blowing-rain intensity and uniformity. Experimental results indicate that the blowing-rain intensity and uniformity both increase with the increasing total water supply flow rate and decrease with the increasing air velocity.
42
Mahmoudian, Jafar, Federico Mazzelli, Adriano Milazzo, Ray Malpress e David R. Buttsworth. "Experiments on water vapour condensation within supersonic nozzle flow generated by an impulse tunnel". International Journal of Multiphase Flow 134 (gennaio 2021): 103473. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2020.103473.
43
SUGIMOTO, Takashi, Atsushi OKAJIMA, Takahiro KIWATA, Shinobu SAITO e Kazutoshi MATSUDA. "Water Tunnel Experiments on the In-Line Oscillation of Circular Cylinders with Finite Length". Transactions of the Japan Society of Mechanical Engineers Series B 71, n. 703 (2005): 753–59. http://dx.doi.org/10.1299/kikaib.71.753.
44
Zhang, J., Y. Shao e N. Huang. "Measurements of dust deposition velocity in a wind-tunnel experiment". Atmospheric Chemistry and Physics Discussions 14, n. 7 (8 aprile 2014): 9439–74. http://dx.doi.org/10.5194/acpd-14-9439-2014.
Abstract (sommario):
Abstract. In this study, we present the results of a wind-tunnel experiment on dust deposition. A new method is proposed to derive dust deposition velocity from the PDA (Particle Dynamics Analysis) particle-velocity and particle-size measurements. This method has the advantage that the motions of individual dust particles are directly observed and all relevant data for computing dust deposition velocity is collected using a single instrument, and therefore the measurement uncertainties are reduced. The method is used in the wind-tunnel experiment to measure the dust deposition velocities for different particle sizes, wind speeds and surface conditions. For a sticky-smooth wood surface and a water surface, the observed dust deposition velocities are compared with the predictions using a dust deposition scheme, and the entire dataset is compared with the data found in the literature. From the wind-tunnel experiments, a relatively reliable dataset of dust deposition velocity is obtained, which is of considerable value for the development and validation of dust deposition schemes.
45
Zhang, J., Y. Shao e N. Huang. "Measurements of dust deposition velocity in a wind-tunnel experiment". Atmospheric Chemistry and Physics 14, n. 17 (1 settembre 2014): 8869–82. http://dx.doi.org/10.5194/acp-14-8869-2014.
Abstract (sommario):
Abstract. In this study, we present the results of a wind-tunnel experiment on dust deposition. A new method is proposed to derive dust deposition velocity from PDA (particle dynamics analysis) particle-velocity and particle-size measurements. This method has the advantage that the motions of individual dust particles are directly observed and all relevant data for computing dust deposition velocity is collected using a single instrument, and thus the measurement uncertainties are reduced. The method is used in the wind-tunnel experiment to measure dust deposition velocities for different particle sizes, wind speeds and surface conditions. For sticky-smooth wood and water surfaces, the observed dust deposition velocities are compared with the predictions using a dust deposition scheme, and the entire data set is compared with the data found in the literature. From the wind-tunnel experiments, a relatively reliable data set of dust deposition velocities is obtained, which is valuable for the development and validation of dust deposition schemes.
46
Zhang, Yu, e Qing Lin Meng. "Experimental Method Study of Climatic Evaporation of Porous Material in Wind Tunnel". Applied Mechanics and Materials 71-78 (luglio 2011): 4449–53. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.4449.
Abstract (sommario):
A hot-humid climatic wind tunnel using wind tunnel technology was developed to simulate the true outdoor dynamic climatic parameters, including solar radiation, air temperature, relative humidity and wind speed, which realized a small-step periodic changing climatic environment of a particular area. To obtain atmospheric evaporation force of porous material, water evaporation experiment representing the impact of climatic elements with atmospheric evaporation force was carried out, then a Penman formula based water evaporation experimental model was built. Considered to different texture of materials, different beginning times and different climatic parameters, porous material evaporation experiments were carried out and an experimental model was established.
47
Liu, Bin, Kerui Fan, Lichao Nie, Xiu Li, Fusheng Liu, Limin Li, Jiansen Wang, Huaifeng Sun e Lei Chen. "Mapping water-abundant zones using transient electromagnetic and seismic methods when tunneling through fractured granite in the Qinling Mountains, China". GEOPHYSICS 85, n. 4 (29 giugno 2020): B147—B159. http://dx.doi.org/10.1190/geo2019-0067.1.
Abstract (sommario):
Severe water inrush currently halts the excavation of the Qinling Water Transportation Tunnel and has even stopped tunneling. Based on the geologic conditions of the construction area, the source of water inrush is abundant groundwater in fractured granite. To accurately predict water inrush, we must know the location, geometry, and boundary information of water-abundant zones before excavation. We have developed a field study of integrated seismic and transient electromagnetic (TEM) applications to map the water-abundant zones ahead of the tunnel face. Before the in-tunnel survey, numerical experiments based on excavation and drilling records verified the feasibility of our scheme. To reveal the fractured zones that may be filled with groundwater, an equitraveltime plane algorithm was used in the seismic data processing. Then, the TEM apparent resistivity was calculated to investigate the water-bearing condition of the fractured zones. To detect the water-abundant zone boundaries, we conducted migration imaging of the TEM pseudowavefield that was extracted from the measured TEM signals. A correlation stacking process to extract the TEM pseudowavefield was used to mitigate the ill-posed effect in the inverse wavefield transformation and obtain boundary information of the water-abundant zones. As expected, the results revealed the depth and geometry of the front and rear boundaries of two water-abundant zones 30 m ahead of the tunnel face, which is consistent with drilling and excavation records after the survey. The results of our case study indicate that the integration of seismic imaging, apparent resistivity imaging, and TEM pseudowavefield migration is an efficient and cost-effective method to provide the location, geometry, and boundary information of water-abundant zones.
48
Man, Ke, Ruilin Liu, Xiaoli Liu, Zhifei Song, Zongxu Liu, Zixiang Cao e Liwen Wu. "Water Leakage and Crack Identification in Tunnels Based on Transfer-Learning and Convolutional Neural Networks". Water 14, n. 9 (3 maggio 2022): 1462. http://dx.doi.org/10.3390/w14091462.
Abstract (sommario):
In order to solve the problems of long artificial time consumption, the inability to standardize the degree of damage, and the difficulty of maintaining data in traditional tunnel disease detection methods, this paper proposes the use of Residual Network (ResNet) models for tunnel water leakage and crack detection. ResNet proposes a residual learning framework to ease the training of networks that are deeper than those previously used. Furthermore, ResNet explicitly reformulates the layers as learning the residual functions of the reference layer inputs, rather than learning the unreferenced functions. The ResNet model is built on the Tensorflow Deep Learning (DL) framework and transfer-learning is used to optimize the model. The ResNet-V1 can be obtained by pre-training in ImageNet. The fully connected layers of the ResNet-V1 were modified to four classifications of tunnel disease. Then, the SoftMax function is used to recognize the tunnel diseases. Four network structures have been chosen, i.e., ResNet34 and ResNet50, with and without Transfer-learning, respectively. Those models were selected for testing and training on the sample dataset, and these four network structures were compared and analyzed using five types of evaluation indicators, which are the confusion matrix, accuracy, precision, recall ratio and F1. In identifying tunnel cracks and water leakage, the accuracy of ResNet50 and ResNet34 using the transfer-learning were 96.30% and 91.29%, and the accuracy of ResNet50 was 5.01% higher than that of ResNet34; for the network structure without the transfer-learning, the accuracy of ResNet50 was 90.36% and ResNet34’s accuracy was 87.87%. These data show that the accuracy of ResNet50 is higher than that of ResNet34 with or without the transfer-learning, and the deep structure framework is superior in the identification of tunnel diseases; secondly, comparing the network structures with and without the transfer-learning, it can be found that using the Transfer-Learning can improve the ResNet network’s accuracy for tunnel disease identification. The experiments and reliability analysis demonstrate the intelligent tunnel disease identification method proposed in this paper, and its good robustness and generalization performance. This method can be used for the rapid identification of cracks and water leakage in a tunnel survey, construction and maintenance, which has practical engineering implications for tunnel disease detection.
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Asalf, Belachew, Rodrigo B. Onofre, David M. Gadoury, Natalia A. Peres e Arne Stensvand. "Pulsed Water Mists for Suppression of Strawberry Powdery Mildew". Plant Disease 105, n. 1 (gennaio 2021): 71–77. http://dx.doi.org/10.1094/pdis-04-20-0735-re.
Abstract (sommario):
Powdery mildew (Podosphaera aphanis) is a destructive and widespread disease of strawberry (Fragaria × ananassa), especially when susceptible cultivars are grown in high plastic tunnels or glasshouses. Many powdery mildews thrive in humid environments but free water films on plant surfaces can inhibit conidial germination of some species. We hypothesized that P. aphanis might be directly suppressed by rain through the action of water films and meteoric water. In repeated experiments, the hydrophobic conidia of P. aphanis collected on the surface of water droplets, resulting in their removal when the droplets rolled over the leaf surfaces and fell to the ground. Meteoric water and water films also damaged conidiophores. Brief midday water mists applied in pulses lasting 1 min each four times per day were as effective as multiple fungicide treatments in suppressing powdery mildew. Rapid drying of the pulsed mists resulted in effective suppression of powdery mildew without consequent increases of fungal pathogens that might benefit from water films. The timing and duration of water sprinkling has been refined to the point where it can provide a commercially relevant degree of suppression of powdery mildew on strawberry in a high-tunnel production system.
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Lelandais, Thomas, Édouard Ravier, Stéphane Pochat, Olivier Bourgeois, Christopher Clark, Régis Mourgues e Pierre Strzerzynski. "Modelled subglacial floods and tunnel valleys control the life cycle of transitory ice streams". Cryosphere 12, n. 8 (27 agosto 2018): 2759–72. http://dx.doi.org/10.5194/tc-12-2759-2018.
Abstract (sommario):
Abstract. Ice streams are corridors of fast-flowing ice that control mass transfers from continental ice sheets to oceans. Their flow speeds are known to accelerate and decelerate, their activity can switch on and off, and even their locations can shift entirely. Our analogue physical experiments reveal that a life cycle incorporating evolving subglacial meltwater routing and bed erosion can govern this complex transitory behaviour. The modelled ice streams switch on and accelerate when subglacial water pockets drain as marginal outburst floods (basal decoupling). Then they decelerate when the lubricating water drainage system spontaneously organizes itself into channels that create tunnel valleys (partial basal recoupling). The ice streams surge or jump in location when these water drainage systems maintain low discharge but they ultimately switch off when tunnel valleys have expanded to develop efficient drainage systems. Beyond reconciling previously disconnected observations of modern and ancient ice streams into a single life cycle, the modelling suggests that tunnel valley development may be crucial in stabilizing portions of ice sheets during periods of climate change.