Total Tunnel Length Research Articles

Distribution Law of the Initial Temperature Field in a Railway Tunnel with High Rock Temperature: A Model Test and Numerical Analysis

The distribution of the initial temperature field of a high-rock-temperature tunnel is critical for determining the tunnel line and the construction scheme. This study used model testing, numerical analysis, and field measurement to investigate the initial temperature field distribution of a tunnel with high rock temperatures. A model test system was developed, and the experimental results show that the boundary conditions set by the model are reasonable. The results show that the temperature along the tunnel line is high in the middle and low at both ends. Obviously, the periodic boundary conditions have a significant influence on the temperature field distribution. Then, the corresponding two-dimensional unsteady numerical model is established, and the numerical model is verified by the model test. Next, the numerical model is applied to the actual Jiwoxiga tunnel, which is a high-rock-temperature tunnel. The results show that the maximum ground temperature in the direction of the Jiwoxiga tunnel line is 52.5 °C, the tunnel lengths with ground temperatures above 28 °C account for 96.25% of the total tunnel length, and the tunnel length with a ground temperature above 45 °C comes to nearly 1200 m. In addition, this result is also verified by the field drilling data and field-measured data after excavation. The effectiveness and accuracy of the numerical model are fully demonstrated. This study provides theoretical support for the design and construction of high rock temperature tunnels.

Five-Stranded Hamstring Tendon Autograft for Anterior Cruciate Ligament Reconstruction

Background: Hamstring tendon (HT) autograft for anterior cruciate ligament (ACL) reconstruction has shown equivalent graft failure rates to bone-patellar-tendon-bone (BTB) with decreased prevalence of anterior knee pain. It should be noted that young athletes, particularly females athletes, may have increased graft failure rates with HT versus BTB. Additionally, HT graft diameters <8 mm have shown worse patient-reported outcomes and higher graft failure rates. Five-strand HT autograft offers a method to increase graft size without utilization of allograft tissue or synthetic material. Indications: This presentation describes the technique for 5-strand HT autograft reconstruction of the ACL. Tips and tricks on graft prep, tunnel placement, tunnel depth, and avoiding pitfalls in surgery are provided. Technique Description: Gracilis and semitendinosus tendon harvest is performed through an L-shaped flap of sartorial fascia. If the 4-strand configuration is <8 mm, the semitendinosus is tripled for a 5-strand configuration. Graft is attached to a 15-mm fixed-length button construct for femoral fixation. The tibial tunnel is typically drilled with the guide through the accessory anteromedial portal. Independent femoral tunnel drilling is then performed via the accessory anteromedial tunnel with the knee in hyperflexion, using an offset guide to aid in tunnel placement. Femoral tunnel is initially reamed to depth of 25 mm and then drilled through the far cortex with a 4.5-mm drill to allow for suspensory fixation. Total length to the lateral cortex is measured and reaming of the tunnel is performed to achieve a 5- to 7-mm difference between total tunnel length to the lateral cortex and reamed tunnel length, assuring room for the button to flip on the femoral cortex. Tibial fixation is achieved by interference fixation versus tying the free suture limbs over a post with a washer. Results: Recent studies show the HT autograft to have similar re-rupture rates for ACL reconstruction compared with other autograft options. Additionally, this option has low donor-site morbidity and has demonstrated significant less anterior knee pain and kneeling pain postoperatively. Discussion/Conclusion: ACL reconstruction with 5-strand HT autograft has shown to be an effective method to increase the graft diameter with low rates of donor-site morbidity.

A coupled hybrid numerical study of tunnel longitudinal ventilation under fire conditions

This paper presents the validation of a coupled hybrid (1D/3D-CFD) modelling methodology, using FDS version 6.7.5, for the first time, with full-scale fire tests. Real fire conditions of the Runehamar tests with maximum heat release rates of 6 MW, 66 MW, and 119 MW are compared by assessing temperature profiles, centreline velocity, backlayering lengths, and maximum temperatures at different locations both upstream and downstream from the fire source. An expression to evaluate the length of the 3D domain where the fire is located is successfully assessed. Also, a pressure boundary condition at one of the portals is suggested to predict more precisely the inner flow conditions. The temperature profiles are accurately predicted with time-averaged differences lower than 20% beyond 40 m downstream from the fire source in the three tests. Furthermore, with the coupled hybrid approach, the backlayering length is estimated accurately with the fire of 66 MW and underestimated in the 6 MW and 119 MW fires, i.e. a maximum difference lower than 4% of the total tunnel length. The validated proposed methodology allows accurate predictions of temperature for tunnel fires and reduces the computational cost between 27% and 75% with respect to a full-CFD numerical model.

Mitigation of the pressure fluctuation arising from high-speed train intersection in tunnels using enlarged tunnel ends

Intense pressure fluctuations generated by the intersection of high-speed trains (HSTs) in a tunnel are unfavourable for the comfort of passengers and the safety of HSTs and tunnel facilities. This study numerically investigated the mitigation principle of the pressure fluctuation impacted upon HSTs using the enlarged tunnel end with taking into account the total tunnel length and the unit number of HSTs. Moving model tests were also performed to validate the numerical method based on the unsteady RANS equations and RNG k-ε turbulence model. The numerical results show that the enlarged end of a tunnel can manifestly alleviate the negative pressure induced by the train intersection and the length ratio of the optimal length of the enlarged section to the total length is in the range of 0.26–0.28. The optimal length of the enlarged section can be implemented by synchronising the contact of the derived waves with the train intersection. Moreover, the increase in the marshalling number of HST augments the mitigation effect of the enlarged section. This study gives insight into the mitigation of the pressure fluctuation in tunnels and can provide valuable data and a theoretical basis for the tunnel design when considering the aerodynamic effect of HST intersection.

Study on Drivers’ Visual Load Features in Lighting Environments of Interior Zones of Extra‐Long Tunnels over 10 km

In extra‐long road tunnels (>10 km), the interior zone accounts for 95% of the total tunnel length. Driving for an extended period in the interior zone of such a tunnel in a monotonous and dimly lit environment causes heavy visual loads for drivers and undermines the safe operation of tunnels and driving comfort. This study investigated the changing patterns of drivers’ visual loads while driving through road tunnels. In a real vehicle experiment, the pupil diameter, fixation duration, electroencephalogram power spectral density, standard deviation of normal to normal, and root mean square of successive differences were used as indicators of drivers’ visual loads. By comparing the differences in psychological and physiological parameters in tunnels of four different lengths, this study discovered the changing pattern of drivers’ visual loads in the interior zone of extra‐long tunnels and merged multi‐source information of various indicators based on the entropy evaluation model to obtain comprehensive visual load values for drivers. The experiment revealed that as the tunnel length increased, the changing patterns of the drivers’ visual load indicators diverged. In particular, the driver’s tension levels began to spike after 180s of driving. The comprehensive visual load values of drivers, combined with the change features of multiple indicators, provide a more accurate and complete assessment of visual loads. The analysis of drivers’ visual load features can provide a theoretical basis for measures to optimise the lighting environment of the interior zone of extra‐long tunnels over 10 km.

Ovipositional preference of potato tuber moth and its damage to different genotypes of potato in free choice condition

Potato tuber moth is a serious pests of potato which cause qualitative as well as quantitative loss on tubers at stores. Major control mechanism is to use chemical pesticide but this pose great hazard risk to the growers and consumers. Therefore this study evaluated tubers of ten potato genotypes viz. CIP 394600.52, CIP 393371.164, Khumal Ujjawal, PRP 296667.2, CIP 393385.39, CIP 395112.32, PRP 226567.2, PRP 0165667.6, CIP 393371.159, and Khumal Upahar against potato tuber moths for their ovipositional preferences and damage potential with nine replication in the laboratory. Number of deposited eggs for four days at eye and outside the tubers on skin, number of tunnel and tunnel length was measured. Least percentage of egg laid eye was least in genotype CIP 394600.52, CIP 393371.164 and variety Khumal Ujjawal respectively. The least number of total eggs laid on eyes was on genotype CIP 394600.52 9 (2.33±1.00) followed by variety Khumal Ujjwal. Although genotype CIP 393385.39 and Khumal Ujjwal was among the most preferred (6.00±2.45) genotype for oviposition, average number of tunnels and average total tunnel length remained very low. Factors such as physical, nutritional, chemical or genetical which may be involved inducing resistance mechanism thus should also be studied and verified.

Maintenance of rail tunnels – Strategy with vision

AbstractRail tunnels in Austria have to be amortized over an economic life of 150 years, so asset allocation has to focus on project control, project support and on predictive maintenance of tunnel lining and dewatering systems. Especially in view of the increase in total tunnel length by more than 100 per cent within the next ten years, the principles of predictive maintenance have to be improved. For this purpose, the development of proofed hybrid multi‐scale methods is necessary. These methods have been used in the past to evaluate stresses in shotcrete linings, and future strategies could use the same methods for stress evaluation in the whole support structure. The second major point concentrates on work on monitoring and prediction of deposits in drain pipes. We have to look closely at filling levels and the degree of hardness of the deposits.

Evaluation of European corn borer Ostrinia nubilalis (Lepidoptera: Crambidae) larval movement and survival in structured and seed blend refuge plantings

Blending Bacillus thuringiensis (Bt) corn and non-Bt corn seeds in the same bag is a convenient and easier compliance solution to satisfy refuge regulations. However, there has been considerable debate and concern about larval movement of the target insects in a seed blend because of its potential effect on the development of resistance. Reported here are studies to determine the larval movement of European corn borers, Ostrinia nubilalis (Hübner), in a seed blend compared to a structured refuge and their effects on survival, feeding injury and larval fitness. Also evaluated is the relative performance of a purple-seeded corn hybrid as a surrogate host plant for tracking gene flow. Seed blend and structured refuge arrangements of Agrisure GT/CB/LL Bt corn expressing Cry1Ab and isoline plants were evaluated at two locations in 2013 and 2014 by manually infesting refuge plants with first and second generation corn borer larvae. The majority of leaf and stalk injury was recorded on the refuge plant, which amounted to 66–83% of the total tunnel length. In both refuge arrangements, plant injury and the number of larvae recovered significantly decreased on neighboring plants with increasing distance away from the refuge plant in the same row. The relative decline in injury was much more pronounced in the seed blend, with neighbor Bt plants experiencing very minor tunneling or no injury at all due to the high dose trait. Eighty-nine percent fewer live larvae were also found on neighbor Bt plants in the seed blend compared to those found in the structured refuge plots. Larvae that moved to Bt plants as well as older instars that were manually placed on Bt plants failed to complete development. Comparison of the number of tunnels and larvae recovered per refuge plant indicated that the seed blend may not produce as many susceptible individuals as those produced in a structured refuge arrangement. Although the purple-seeded hybrid showed lower levels of ear and stalk injury, it could serve as an appropriate surrogate refuge plant to track gene flow.

Femoral and Tibial Graft Tunnel Parameters After Transtibial, Anteromedial Portal, and Outside-In Single-Bundle Anterior Cruciate Ligament Reconstruction

Background: Anatomic graft tunnel placement is recommended in anterior cruciate ligament (ACL) reconstruction to restore knee joint stability and function. Transtibial (TT), anteromedial portal (AMP), and outside-in (OI) retrograde drilling surgical techniques have been described for tibial and femoral bone tunnel preparation. Purpose/Hypothesis: The purpose of this study was to evaluate the bone tunnel parameters and compare the ability of 3 different surgical techniques to achieve placement of the ACL femoral and tibial bone tunnels at the center of the native ACL femoral and tibial attachment sites. The hypothesis was that tunnel placement using an AMP or OI technique would result in optimized tunnel parameters and more closely reconstruct the center of the native ACL femoral attachment site. Study Design: Cohort study; Level of evidence, 3. Methods: The study population consisted of 100 patients undergoing anatomic single-bundle ACL reconstruction using multiple-stranded hamstring tendon grafts. In group 1 (n = 36), the femoral tunnel was drilled using a TT surgical technique; in group 2 (n = 32), the femoral tunnel was drilled through an AMP; and in group 3 (n = 32), the femoral tunnel was created by use of an OI technique with retrograde drilling. Computed tomography (CT) scans were obtained postoperatively, and characteristics of femoral and tibial tunnel apertures were correlated to femoral and tibial measurement grid systems. The position of the resulting tibial and femoral bone tunnels for each group was compared with the center of the native ACL attachment sites. Results: There were statistically significant differences (P < .05) for the ACL femoral tunnel between the 3 groups with respect to intercondylar height, total tunnel length, graft fixation length, tunnel axis, and tunnel entry angle. Statistically significant differences (P < .05) were found for the ACL tibial tunnel with respect to anteroposterior tunnel position and sagittal tunnel axis between the TT and both the OI and AMP techniques. The OI surgical technique produced more oblique and anatomically correct femoral tunnel apertures and longer femoral tunnel lengths compared with the AMP technique. Both AMP and OI techniques resulted in a more precise replication of intercondylar tunnel depth and height. There was no statistically significant difference for graft fixation length between the AMP and OI techniques. Conclusion: The AMP and OI surgical techniques were superior in positioning the ACL femoral tunnel at the center of the native ACL attachment site compared with the TT technique. An acceptable graft fixation length was obtained for all 3 surgical techniques.

A socio-economic analysis of Smart Infrastructure sensor technology

Smart Infrastructure wireless sensor technology is designed to provide a new way of managing infrastructure. These wireless sensors are able to share information on infrastructure conditions across a range of agencies without human intervention. Thus, false readings can be corrected automatically and further incidents should be avoided. The advantages of using these wireless sensors are their reliability, low-cost, low power and fast deployment characteristics. In this paper, we conduct a socio-economic analysis on the application of Smart Infrastructure sensor technology to the British rail tunnel industry using Monte Carlo simulation. The study would offer insights on the feasibility of the technology. Furthermore, the simulation forecast would bring the deeper understanding of the wider socio-economic implications, which is important for decision makers. Our study shows that the mean value of the cumulative net present value for the application of the Smart Infrastructure sensor to the British tunnel market in the year 2056 is estimated to be US$40million. According to the sensitivity analysis, the key parameters, which have significant impacts on the net present value, are the maximum target market penetration rate, base year disruption cost due to tunnel closure, total tunnel length, and annual number of tunnel collapses.

On the Importance of the MIMO Channel Correlation in Underground Railway Tunnels

This paper deals with MIMO channel modeling according to the correlation level in underground railway tunnels for various antenna configurations for the transmitting and receiving arrays. MIMO channel matrices have been computed with a 3D ray-tracing based software at 2.4 GHz and 5.8 GHz in two different tunnel environments: 1) a 1-track empty tunnel with a square cross section, 2) a 1-track tunnel with a square cross section in which a train is parked between the transmitter and the receiver. In this paper, two different strategies are investigated to model the MIMO channel using the Kronecker and the Weichselberger correlation based channel models. The first one is to model the MIMO channel using a single model over the total tunnel length. The second one takes into account the correlation at the receiving side according to the transmitter-receiver distance. In the latter solution, it is possible to isolate specific areas in the tunnel with specific correlation properties and model them in an independent way to take them into account in a system simulation. In this paper, these two modeling strategies are compared in terms of channel capacity.

Moscow largest highway tunnel construction project

Construction of Lefortovo Tunnel - the biggest urban underground structure in Moscow - was successfully completed in February 2003. The tunnel, being the final section of the Third Transportation Ring Road in Moscow, will be opened for traffic by the end of 2003. Total tunnel length makes 3.3 km, its main section (2222 m) will stretch under 'Lefortovo- Nemetskaya Sloboda' nature reserve, where historical monuments - buildings of the XVIII century, fountains and ponds are situated in a vast park area. The tunnel will have three traffic lanes in each direction to provide the design capacity of 3800 vehicles per hour in each direction. Construction was carried out in congested urban environment under challenging geological conditions, which required the use of 14.2 m diameter bentonite slurry pressure balance Herrenknecht Mixshield (TBM). In the course of the excavation, several innovative tunneling technologies were practiced: providing for the tunnel face stability by applying compressed air upon the bentonite suspension, air pressure being adjusted depending on hydrostatic conditions; transportation of excavated soil through special pipelines and subsequent separation of muck from the bentonite slurry; continuous grouting of annulus beyond the tunnel lining with mortar of a special mix; fully automatic and semi-automatic TBM driving. At the deep section, tunnel lining was made of high-precision reinforced concrete precast lining segments with the two rows of elastomer sealing gaskets. At shallow sections constructed by the cut-and-cover method, lining was made of cast-in-situ concrete frame structures with waterproofing membrane. Continuous structural and environmental monitoring performed during the construction allowed timely measures to be taken to provide for the work safety and to effectively protect existing buildings, structures and utilities by applying various soil stabilisation methods, including compensation grouting. The adopted innovative technologies along with the adequate construction management allowed the tunnel drive to be successfully completed within 1 year with practically no settlements of existing buildings, structures and utilities (from 6 to 12 mm surface settlements were reported which is far inferior of the accepted standards). Adequate design of various tunnel elements such as the in-situ cast reinforced concrete carriageway slab, facilities for allocation of power substations and pump chambers, escape corridors under the carriageway slab for evacuation of people in case of emergency and fire, automatic fire alarm systems, fire fighting means and smoke extraction systems, etc., will all together contribute to the safe tunnel operation. (A). Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.

Rethinking High-Level Waste Disposal: Separate Disposal of High-Heat Radionuclides (90Sr and 137Cs)

An alternative approach for disposal of high-level waste (HLW) is proposed. HLW would be separated into two fractions: (a) the high-heat radionuclides (HHRs), e.g., 90Sr and 137Cs, and (b) the low-heat radionuclides (LHRs), which are all the remaining radionuclides. These two categories of waste would be disposed of separately in different sections of the repository or different facilities.The LHRs in the HLW contain the long-lived radionuclides that control the repository performance requirements that in turn necessitate (a) expensive waste packages (WPs) and (b) limiting the repository temperatures to avoid repository performance degradation. To limit repository temperature, the amount of HLW per WP is limited and the WPs are spread over a large area. If the decay-heat-generating HHRs are removed from HLW, the repository design is not controlled by decay heat. The resultant LHR repository size (area, number of WPs, total tunnel length) may be reduced to <20% of the size of a conventional repository. With a waste partitioning and transmutation process that includes removal of the minor actinides (americium and curium) from the LHR wastes, significant further reductions in repository size are possible. The minor actinides are the next largest heat generators in LHR wastes.Separate management of HHRs does require (a) separation of the HHRs from the HLW and (b) a separate HHR disposal facility. The HHRs are disposed of in a separate lower-cost facility made possible by the limited lifetimes (T1/2 ~ 30 yr) of the HHRs. There are potentially significant gains in economics and repository performance for separate management of HHRs and LHRs in some types of fuel cycles.

Burrow architecture and turbative activity of the thalassinid shrimp Callianassa subterranea from the central North Sea

The architecture and development of the burrows of the endobenthic shrimp Callianassa subterranea from the central North Sea were studied in sediment-filled containers and thin cuvettes in the laboratory. Three-dimensional burrows of 81 shrimps were used to describe the 3-dimensional burrow architecture. In total, 41 shrimps made 2-dimensional burrows in cuvettes tailored to their body widths. Development of 8 burrows over time was registered by regularly mapping burrow outlines and sediment surface levels. Excavation Velocities and sediment expulsion rates were derived from changes in the burrow outlines and sediment surface levels on the maps. The total tunnel length increased at a rate of 23.4 +/- 6.0 mm h(-1) during the initial stage of burrow development. The length increase levelled off during the completion of the first and second U-tubes to 5.6 +/- 1.8 mm h(-1). Initial sediment expulsion rates up to 15.0 cm(3) d(-1) were established. The average sediment expulsion rate was 1.080 +/- 0.096 cm(3) d(-1). Extrapolation to a yearly dry weight (dry wt) sediment turnover, including population density and water temperature effects, resulted in an estimate of 15.5 +/- 2.7 kg dry wt m(-2) yr(-1), equivalent to a 1.2 cm layer. Samples of burrow lining, expelled sediment and unprocessed sediment did not show changes in grain size distributions or organic content due to manipulation or processing by C. subterranea. Burrow development experiments carried out in enriched seawater systems did not reveal consistent effects of particulate organic matter (POM) on sediment expulsion rates or on the composition of processed or unprocessed sediment.

The History and Structure of a Large Warren of the Rabbit, Oryctolagus-Cuniculus, at Canberra, Act

A 5-year-old rabbit warren in a 33-ha enclosure had 150 entrances and a total tunnel length of 517 m; it was estimated that 10.35 m*3 of soil had been excavated from the warren. Penetrometer readings indicated the presence of a hard layer in the soil at 600-700 mm. The depth of the warren was limited by this hard layer, the rabbits not having excavated below 700 mm. The hard layer had a low permeability, and flooding of the warren resulted in the deaths of nestling rabbits.