Tunnel Entrance Research Articles

BIOMECHANICAL EFFECTS OF ASPECT RATIO OF THE KNEE DURING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION SURGERY

The objective of this study was to analyze the biomechanical effect of an implanted ACL graft by determining the tunnel position according to the aspect ratio (ASR) of the distal femur during flexion-extension motion.To analyze biomechanical characteristics according to the ASR of the knee joint, only male samples were selected to exclude the effects of gender and 89 samples were selected for measurement. The mean age was 50.73 years, and the mean height was 165.22 cm. We analyzed tunnel length, graft bending angle, and stress of the graft according to tunnel entry position and aspect ratio (ratio of antero-posterior depth to medio-lateral width) of the articular surface for the distal femur during single-bundle outside-in anterior cruciate ligament reconstruction surgery. We performed multi-flexible-body dynamic analyses with wherein four ASR (98, 105, 111, and 117%) knee models.The various ASRs were associated with approximately 1-mm changes in tunnel length. The graft bending angle increased when the entry point was far from the lateral epicondyle and was larger when the ASR was smaller. The graft was at maximum stress, 117% ASR, when the tunnel entry point was near the lateral epicondyle. The maximum stress value at a 5-mm distance from the lateral epicondyle was 3.5 times higher than the 15-mm entry position and, the cases set to 111% and 105% ASR, showed 1.9 times higher stress values when at a 5-mm distance compared with a 15-mm distance. In the case set at 98% ASR, the low-stress value showed a without-distance difference from the lateral epicondyle.Our results suggest that there is no relationship between the ASR and femoral tunnel length, A smaller ASR causes a higher graft bending angle, and a larger ASR causes greater stress in the graft.

Mobile measurement of vehicle emission factors in a roadway tunnel: A concentration gradient approach

Tunnels are the preferred experimental environments for estimating vehicle emission factors (EFs) under real-world driving conditions. In this study, online measurements of traffic-related air pollutants (including CO2, NOX, SO2, O3, particulate matter [PM], and volatile organic compounds [VOCs]) were conducted using a mobile laboratory in the Sujungsan Tunnel in Busan, Korea. Mobile measurements generated concentration profiles of the target exhaust emissions inside the tunnel. These data were used to produce a zonation of the tunnel, i.e., mixing and accumulation zones. There were differences between the CO2, SO2, and NOX profiles, and a starting point that was free from ambient air mixing effects could be set at 600 m from the tunnel entrance. The EFs of vehicle exhaust emissions were calculated using pollutant concentration gradients. The average EFs for CO2, NO, NO2, SO2, PM10, PM2.5, and ∑VOCs were 149,000, 380, 55, 29.2, 9.64, 4.33, and 16.7 mg km−1·veh−1, respectively. Among the VOC groups, alkanes contributed more than 70% of the VOC EF. Mobile measurement-derived EFs were validated using the conventional EFs from stationary measurements. The EF results from the mobile measurements matched those from the stationary measurements, while the absolute concentration differences between them implied complex aerodynamic movements of the target pollutants inside the tunnel. This study demonstrated the usefulness and advantages of applying mobile measurements in a tunnel environment and indicated the potential of the approach for observation-based policymaking.

Engineering D-allulose 3-epimerase from Clostridium cellulolyticum for improved thermostability using directed evolution facilitated by a nonenzymatic colorimetric screening assay

D-Allulose 3-epimerase (DAEase) is a biocatalyst of concern for D-allulose enzymatic synthesis; however, it exhibits comparatively low thermal stability. To facilitate the directed evolution of DAEase, a nonenzymatic colorimetric assay was developed for high-throughput screening of enhanced DAEase mutants. One desirable mutant, MT4 (S38F/F42N/A70P/T119P), was screened based on purifying selection of the randomly mutagenesis library and positive screening of the randomly shuffled library. Compared to the wild-type, the combinational mutant MT4 had higher catalytic activity (1.23-fold) and showed 5, 6.2, and 6.92 °C increases in Topt, T50, and Tm values, respectively. Furthermore, at 60 °C, the t1/2 value of mutant MT4 was 7.30nullh, exhibiting an 11.4-fold increase in comparison to the wild-type. When the mutant MT4 was used in D-allulose production, the yield reached 28.3%, higher than the 25.1% achieved by the wild-type. Dynamic property and structural change analysis demonstrated that the enhanced properties of mutant MT4 were largely attributed to the β4-α4 loop rigidification and active-site tunnel entrance constriction. This work expands the industrial application value of DAEase and provides a robust method as the basis for further protein engineering to achieve better performance of this enzyme.

Study on Radial and Longitudinal Zoning of Insulation Layer in Alpine Tunnel under Wind Field

The unreasonable setting of thermal insulation layer in high cold tunnels not only increases the maintenance cost of tunnels, but also weakens the anti-freezing and cold resistance of the tunnels. In order to optimize the setting of thermal insulation layer in an Alpine tunnel, relying on Dabanshan tunnel in Qinghai Province, three schemes of radial and longitudinal thermal insulation region of thermal insulation layer were adopted, and the temperature field of the surrounding rock was numerically analyzed. The results show that the uneven region scheme of 9 cm-8 cm-7 cm and 10 cm-9 cm-8 cm insulation layer can effectively reduce the freezing area of the lining and the surrounding rock, the freezing region at the tunnel entrance is significantly reduced, and there is no lining freezing region within the depth of 30–750 M. The research results can provide guidance for the partition wall setting of radial and longitudinal insulation layers of Alpine tunnels. In addition, it has considerable economic advantages for the reduction in engineering construction costs.

Temperature and humidity prediction of mountain highway tunnel entrance road surface based on improved Bi-LSTM neural network

Temperature and humidity prediction of mountain highway tunnel entrance road surface based on improved Bi-LSTM neural network

Exploring the effects of work zone on vehicular flow on ring freeways with a tunnel using a three-lane continuum model

Freeway work zone forms as a result of traffic crash or road rehabilitation. To ascertain the effects of work zone with lane II completely blocked on vehicular flow on ring freeways with a tunnel, a three-lane continuum model is put forward. The mandatory net lane-changing rate from lane II to lane I or III just upstream of the work zone is described by a random number model, with the random number being produced within a small range around a median based on a golden section analysis. The net-changing rate between adjacent lanes is described using a lane-changing time on the basis of an assumption: the time ratio to relaxation time equals infinity when the absolute value of traffic densities between the two adjacent lanes is less than 1 veh/km, implying that the net-changing rate is zero; otherwise, the time ratio is inversely proportional to the vehicular spatial headway, which is equal to unity for traffic flow at saturation state, but infinity when the traffic flow is completely jammed. It is assumed that the freeway is a three lane ring with a total length of 100 km, and has a tunnel with a speed limit of 60 km/h and a length of 1.6 km located downstream the work zone with a length of 0.16 km. The free flow speeds on lanes I, II, and III are 120 km/h, 100 km/h, and 85 km/h, respectively. For the vehicular flow on the ring freeway with a tunnel, numerical simulations based on the three-lane continuum model are carried out with a reliable numerical method of high accuracy. It is found that the vehicular flow has two thresholds of traffic jam formation, one depending upon the tunnel and the other upon the work zone. The tunnel triggers a traffic jam when the initial density normalized by jam density is equal to the first threshold 0.15, and the work zone originates another traffic jam when the normalized initial density equals the second threshold 0.19. The freeway tunnel plays a dominant role in the prediction of mean travel time as soon as the tunnel has generated a traffic jam at the tunnel entrance. For the vehicular flow at unsaturated state, the average speed through the tunnel is about 26.67 km/h. When the normalized initial density exceeds the second threshold 0.19, the mean travel time through every lane increases with the initial density linearly. Vehicle fuel consumption can be estimated by interpolation with the time averaged grid traffic speed and an assumed vehicle performance curve. It is found that the vehicle fuel consumption is lane number dependent, and distributes with the initial density concavely, as well as has a value in the range of 6.5 to 8.3 l.

Engineered aldoxime dehydratase to enable the chemoenzymatic conversion of benzyl amines to aromatic nitriles

A chemoenzymatic strategy has been implemented to synthesize nitriles from benzyl amines under mild conditions. Aldoxime dehydratase (Oxd) plays a decisive role to convert aldoximes into corresponding nitriles. However, natural Oxds commonly exhibit extremely low catalytic capacity toward benzaldehyde oximes. Here, we engineered the OxdF1 from Pseudomonas putida F1 to enhance its catalytic efficiency toward benzaldehyde oximes by a semi-rational design strategy. The protein structure-based CAVER analysis indicates that M29, A147, F306, and L318 are located adjacent to the substrate tunnel entrance of OxdF1, which were responsible for the transportation of substrate into the active site. After two rounds of mutagenesis, the maximum activities of the mutants L318F and L318F/F306Y were 2.6 and 2.8 U/mg respectively, which were significantly higher than the wild OxdF1 of 0.7 U/mg. Meanwhile, the lipase type B from Candida antarctica was functionally expressed in Escherichia coli cells to selectively oxidize benzyl amines to aldoximes using urea-hydrogen peroxide adduct (UHP) as an oxidant in ethyl acetate. To merge the oxidation and dehydration reactions, a reductive extraction solution was added to remove the residue UHP, which is critical to eliminate its inhibition on the Oxd activity. Consequently, nine benzyl amines were efficiently converted into corresponding nitriles by the chemoenzymatic sequence.

Calculation and optimization of slope reinforcement at tunnel entrances—taking manyanpo tunnel as an example

Slope reinforcement is a common method to solve the problem of slope instability, and reasonable optimization of the corresponding support parameters is crucial for practical engineering. In this paper, the slope support method of Manyanpo tunnel entrance section is taken as an example, and the theoretical calculation method is used to optimize the project cost. Combined with the orthogonal test, the sensitivity analysis of the influencing factors of the stability of the support system and the selection of the optimal parameter combination scheme are carried out. Then, based on flac3d software, the optimization scheme is compared with the original design scheme. The results show that the safety factor of the optimized scheme is increased from 1.32 to 1.43 compared with the actual project. The optimized support parameters have better control effect on the displacement of the slope, especially in the Z direction. The optimized parameters have better support effect. This study can provide reference for the optimization design of slope engineering support.

Transient binding sites at the surface of haloalkane dehalogenase LinB as locations for fine-tuning enzymatic activity.

The haloalkane dehalogenase LinB is a well-known enzyme that contains buried active site and is used for many modelling studies. Using classical molecular dynamics simulations of enzymes and substrates, we searched for transient binding sites on the surface of the LinB protein by calculating maps of enzyme-ligand interactions that were then transformed into sparse matrices. All residues considered as functionally important for enzyme performance (e.g., tunnel entrances) were excluded from the analysis to concentrate rather on non-obvious surface residues. From a set of 130 surface residues, twenty-six were proposed as a promising improvement of enzyme performance. Eventually, based on rational selection and filtering out the potentially unstable mutants, a small library of ten mutants was proposed to validate the possibility of fine-tuning the LinB protein. Nearly half of the predicted mutant structures showed improved activity towards the selected substrates, which demonstrates that the proposed approach could be applied to identify non-obvious yet beneficial mutations for enzyme performance especially when obvious locations have already been explored.

Influence of Segmented Linings on the Micro-Pressure Wave of Tunnels

When the tunnel has damages such as deformation and cracking, the lining structure should be set to reinforce the tunnel. In this study, a three-dimensional numerical method is performed to study the aerodynamic effects caused by the train passing through a tunnel with segmented linings at 350 km/h. The influence of the numbers, thickness, location, and types of the segmented lining structure on MPW is analyzed. The results show that the segmented linings located at the middle of the tunnel have a better mitigation effect on MPW than that of the normal linings, which increases with the segment number and the thickness of the linings. When the damage occurs near the entrance of the tunnel, a segmented lining structure with a constricted section slightly away from the tunnel entrance can be used to reduce its adverse effect on MPW.

Design Method of Combined Gradient Dimming Structures for Highway Tunnels

The notable brightness difference between the inside and outside of a tunnel is a major issue restricting the safe driving and energy-saving conditions of highway tunnels. The installation of a shading structure at the entrance of a highway tunnel could resolve this problem. This method is equivalent to moving the entrance zone outside so that light is smoothly transmitted into the tunnel, which is called pretunnel lighting. In this research, the shading structure is selected as the research object. First, the shading effects of pergolas and sunshades of different cross-sectional forms are analyzed. Second, choosing the Jiulongpo Tunnel in Chongqing as an example, through DIALux software modeling and analysis, the tunnel sunshade is selected as the primary shading structure, which is better than the pergola in terms of the average luminance value and uniformity of luminance. Third, based on the idea of gradient dimming outside the tunnel, three kinds of combined gradient dimming sunshades are designed. Considering the influence of the season, weather and orientation, the optimal design scheme is determined in detail. Finally, the energy-saving benefits are calculated of the installation of a tunnel sunshade to replace the enhanced lighting in Threshold zone 1 (TH1) combined with gradient dimming lighting in Threshold zone 2 (TH2). The results show that the combined gradient dimming sunshade in Scheme 3 (70% + 40% + 20% + 10%) is optimal. The combined gradient dimming sunshade could decrease the variation in luminance inside and outside the tunnel and reduce the artificial lighting intensity in the entrance zone, which could facilitate safe driving and energy savings.

Study of unsteady aerodynamic performance of a high-speed train entering a double-track tunnel under crosswind conditions

Significant variation exists in the aerodynamic performances of high-speed trains (HSTs) traveling in different infrastructure scenarios. When high-speed trains travel from one infrastructure scenario to another, the aerodynamic loads acting on the trains change significantly. To investigate the safety as a HST enters a tunnel under crosswind conditions, the unsteady aerodynamic performance of the HST and the flow structures around the train were numerically studied. The results demonstrated that the flow field and the pressure field were symmetrically distributed under conditions with no crosswind, while the distribution of the flow field and the pressure field were clearly asymmetric when crosswinds were present at the tunnel entrance. Furthermore, the flow structures near the train and the pressure distributed on the train surfaces outside the tunnel were most severely affected by the presence of crosswinds. Vortex structures appeared on the windward side surface of the train inside the tunnel and on the leeward side surface of the train outside the tunnel during the entrance of the train into the tunnel. Due to the sudden changes in the flow and the pressure as the train entered the tunnel, the aerodynamic loads changed drastically, and the variations of each vehicle were different, resulting in complex dynamic responses, including lateral vibrations and pitching movement. In particular, the aerodynamic performance of the rear vehicle was the worst as the train entered the tunnel when no crosswind conditions existed, while the head vehicle was the most negatively affected for safe operation of the HST when strong crosswinds were present at the tunnel entrance.

Application of Helicopter-Borne and Ground–Airborne Electromagnetic Detection to Tunnel Engineering Investigation

The Cedaya-S340 Holgutu Highway Construction Project is located in the Mongolian Autonomous Prefecture of Bayingolin in the Xinjiang Uygur Autonomous Region. It is an important traffic channel that connects Luntai County and Hejing County at the southern foot of Tianshan Mountains. As the major component of the highway project, the Huola Mountain Tunnel has a sharp topographic relief, and, therefore, commonly used land geophysical detection instruments cannot work on it. Therefore, we conducted a qualitative survey on the ground-to-air and airborne electromagnetic detection methods used at the Huola Mountain Tunnel site to provide basic data for the design of highway tunnels. The geophysical survey summarized the ground–airborne frequency-domain electromagnetic method (GAFEM) and the helicopter-borne time-domain electromagnetic method (HTEM) developed by Jilin University, and measured 15 measuring lines. Apparent resistivity imaging was performed for each section, and the results were consistent. This study comprehensively analyzed the apparent resistivity profile and geological mapping data. Then, the study inferred the major stratigraphic boundaries, fault fracture zones, rock fragmentation, weakness, karst development, and water content in accordance with background value, low-resistivity anomaly shape, low-resistivity anomaly value, and gradient value in the apparent resistivity profile. Finally, the study identified the scope of two main low-resistivity anomalies, located at the tunnel entrance and exit, respectively, which are basically consistent with the known fault location. The results of this study show that on the basis of the apparent resistivity maps of GAFEM and HTEM, the overall distribution law is basically consistent with site landform, hydrogeology, tectonic geology, and aerial image data. The results provide guidance for the construction of the Huola Mountain Tunnel and ensure the construction safety and progress of the tunnel.

Psychoacoustic Analysis of Various Train Pass-by Noise Using

Due to the recent high speed of railway, noise and vibration generated during operation has emerged as a major social problem. Specially, the internal noise of railway varies depending on various operating conditions such as speed, vehicle crossings, and tunnel entry, and has a great effect on the riding comfort of passengers. In this study, an evaluation method for binaural noise of train pass-by noise and a simple wave field model which can reflect the Doppler effect are examined. To reflect the binaural characteristics of train pass-by noise, binaural measurements were conducted for several types of train, different measurement distances and various measurement angles. The annoyances of measured binaural noises were analyzed using conventional sound pressure level, psychoacoustic metrics, and their rate of change. Also, the noise emitted from high-speed railways was measured and characterized. By its analysis result, moving sounds were synthesized considering an initial frequency and a frequency shift. The synthesized sounds were convolved to reflect binaural condition. Auditory experiments were conducted using the synthesized moving sound stimuli, and the effects of the Doppler frequency shift on annoyance of moving sound sources were obtained.

Effects of Entrance Shape and Blast Pocket on Internal Overpressure Mitigation for Protective Tunnels Exposed to External Detonation on the Ground

This study presents a numerical analysis to reduce the overpressure inside protective tunnels for external detonations. A three-dimensional computational fluid dynamics model of a tunnel subjected to detonation for a hemispherical charge with a charge weight of 555 kg and a standoff distance of 7.6 m was established, based on a mesh sensitivity study to obtain an optimal element size, stability analysis of overpressure, and validation study to evaluate the accuracy of the numerical results based on Unified Facilities Criteria (UFC) 3-340-02. A parametric analysis was performed using the validated numerical model to investigate the effects of the entrance shape and blast pockets on the reduction in the maximum overpressure. The maximum overpressures were effectively reduced as the slope angle of the tunnel entrance decreased and the length of the blast pocket divided by the tunnel width decreased. An optimized shape of the tunnel was proposed based on the numerical results, where the peak overpressures were reduced by a maximum of 64.5%. This study aims to protect facilities, personnel, and equipment and further reduce construction costs by lowering the overpressure rating of blast valves in protective tunnels.

The position of the median nerve in relation to the palmaris longus tendon at the wrist: a study of 784 MR images.

Iatrogenic injury of the median nerve has been reported after endoscopic carpal tunnel release and corticoid injection. In 784 MR images of the wrist, the position of the median nerve in relation to the palmaris longus tendon was analysed. The ulnar edge of the median nerve was found medial to the palmaris longus tendon in 14% and 36% of patients at the proximal wrist crease and entrance of the carpal tunnel, respectively, compared with 23% and 40% of patients with carpal tunnel syndrome (88 patients). The position of the median nerve in relation to the palmaris longus tendon varies widely. It is suggested that the palmaris longus tendon may not be considered a safe landmark to locate the position of the median nerve and care should be taken when introducing an endoscopic instrument or during steroid injection for carpal tunnel syndrome.Level of evidence: IV.

Explosion or Tectonic Earthquake? Evidence That an ML 3.7 Seismic Event Occurred near North Korea’s Nuclear Test Site on 11 February 2022

Abstract Discriminating between tectonic earthquakes and underground explosions in the monitoring of possible underground nuclear tests has become more challenging following the increase in seismicity at the Punggye-ri nuclear test site after North Korea’s sixth nuclear test conducted in 2017. In this article, we discuss how to distinguish between explosions and moderate-magnitude tectonic earthquakes around the Punggye-ri test site. For an ML 3.7 seismic event that occurred near the Punggye-ri test site on 11 February 2022, we precisely relocated the source epicenter, determined the possible depth, identified the P first motions, measured the P/S amplitude ratios, and compared the seismic waveform details with those of North Korea’s historical nuclear test explosions and tectonic earthquakes. The results showed that (1) the epicenter is farther away from the tunnels under Mt. Mantap, and no tunnel entrances and shafts are found around the epicenter in the latest satellite images; (2) the source depth is 5.5 km, which is greater than the ordinary depth of underground nuclear tests; (3) negative P first motions were observed; (4) the P/S amplitude ratios are significantly different from those of North Korea’s previous nuclear tests; and (5) the waveform details are similar to previous tectonic aftershocks rather than historical nuclear test explosions. Our findings suggest that this seismic event was a tectonic earthquake rather than an underground explosion.

A morphological analysis of historic buildings entries using affordable photogrammetry techniques: Old Tripoli, Lebanon

This article documents and compares selected arched and vaulted entrances of historic buildings in Old Tripoli, Lebanon. The aim is to capture the entrances and their immediate context using low-cost photogrammetry to contribute to the safeguarding process of these endangered monuments. The possibilities of recording the micro as well as macro elements of entry spaces for specific typologies, such as schools, khans, residences and places of worship, are explored in the context of a city under the threat of armed conflict, neglect and environmental risks. Micro-scale analysis focuses on forms such as shape, height, and street width, regardless of the building entry's function. Macroscale analysis considers a typical barrel-vaulted tunnel entry to a historic, residential sector of the city where a 3D photogrammetry model demonstrates the form and function of this network of spaces. The research methodology is divided into two processes: the first is a photographic survey of the entrances using a mobile phone camera, followed by the use of both free and educational licensed photogrammetry software to align and develop the captured images into 3D digital models. The second process is conducting interviews with selected stakeholders, such as historians and building custodians to elicit their stories compared to our understanding of the digitally captured 3D buildings and the wider historic city of Tripoli. We argue that affordable photogrammetry methods are necessary and effective. Acknowledging the limitations of these methods, this article argues that the outputs of the implemented methods not only contribute to the identification of the significance of these monuments, but also provide a valuable set of information to assist in the different processes of safeguarding these endangered assets.

Dynamic performance and damage assessment of a shallow buried tunnel under internal explosion

The tunnel entrance is usually made of arch members buried at shallow depths. These contribute to the greater performance of the tunnel under static or seismic loading. If an explosion occurs in the shallow buried tunnel, the tunnel arch at the entrance might be destroyed by the intense blast loading, thereby causing the collapse of the tunnel entrance or the surrounding ground. Hence, it is extremely important to investigate the dynamic behavior of a shallow buried tunnel arch under the conditions of an internal explosion and to evaluate its damage after the blast. In this paper, four scaled tunnel arch structures were fabricated and tested for their anti-blast performance under internal explosion. The following laboratory static load test was conducted on the undamaged and blast-damaged specimens to obtain their maximum and residual bearing capacities, respectively. The field blast test results showed that the tunnel arch experienced local punching failure under the internal contact explosion, and the dimensions of the failure zone increased as the explosive equivalent increased. In addition, for the same explosive equivalent, the residual bearing capacity of the specimen after the contact explosion at the arch crown was the lowest among other blast-damaged specimens, indicating that the damage on the arch crown significantly deteriorated the bearing capacity and stiffness of the tunnel arch. The finite element (FE) model of the shallow buried tunnel arch under the internal explosion was developed by adopting the arbitrary Lagrangian–Eulerian (ALE) algorithm in LS-DYNA and validated on the actual measurements from the field blast test. It is shown that the results from the FE model and field blast test measurements compared well in terms of damage pattern, crater diameter, acceleration and reflected overpressure readings. The full restart method in LS-DYNA was further employed to calculate the bearing capacity of the specimens. Finally, the damage levels of the blast-damaged specimens were assessed by taking the residual bearing capacity of the tunnel arch as an indicator. The damage assessment charts for the shallow buried tunnel arch under the conditions of an internal explosion were further established. From the chart, the blast resistance of the shallow buried tunnel arch can be quickly assessed under different internal blast loading conditions. This research is of direct significance for the design of the shallow buried structures with increased blast resistance.

Research on Traffic Safety at Tunnel Entrance and Exit

Highway tunnel entrances have a high rate of expressway traffic accidents. In this paper, the reasons for the high incidence of traffic accidents at highway tunnel entrances are analyzed in detail, and corresponding solutions are proposed, hoping to provide some reference to relevant parties.