Left Tunnel Research Articles

Flow Characteristics and Escape-Route Optimization after Water Inrush in a Backward-Excavated Karst Tunnel

AbstractIn this study, using the background of Qiyueshan high-risk karst tunnels, flow characteristics and escape-route optimization after water inrush in a backward-excavated karst tunnel are researched. First, five case studies are simulated and investigated under different velocities of water inrush. One special probing line is selected, respectively, in the left tunnel, cross passage, right tunnel, and along the height direction of the tunnel centerline. For each probing line, the corresponding velocity and pressure curves are obtained based on the numerical simulation results. The change rules of velocity and pressure under the five water-inrush velocities are analyzed and concluded. Then, focusing on one velocity of water inrush, the variation laws of velocity and pressure in a plane are analyzed and discussed by selecting a series of probing lines. Flow characteristics of water after inrushing in a backward-excavated tunnel are summarized. Finally, for such cases, the optimized escape routes are ma...

Investigation of response of metro tunnels due to adjacent large excavation and protective measures in soft soils

The inevitable influence of large excavation in soft soils on nearby tunnels is of great concern in practice. In this paper, the influence of a nearby large excavation on existing metro tunnels of the Ningbo Metro Line 1 in sensitive soft soils is investigated and presented. Considerable displacement in the left tunnel closer to the excavation induced by the nearby excavation was revealed by field monitoring. Visible cracks and leakages were observed in left tunnel linings. Three dimensional numerical simulations are conducted to investigate the responses of the ground and left tunnel due to the adjacent excavation. The development of bending moment and displacement of the left tunnel during different construction stages of the nearby excavation is obtained. Then the interaction mechanism between the nearby excavation, surrounding soils and existing twin tunnels is investigated, which is of significance to the interpretation of the influence of the nearby excavation on the existing twin tunnels. Several protective measures for alleviating the influence of adjacent excavation on left tunnel are studied, including divided excavation, soil improvement and a cut-off wall. It is found that the left tunnel is influenced to varying degrees during different construction stages and the time effect is distinct for this large excavation in soft soils, which would be suggestive to engineers to pay more attention to the protection of adjacent tunnel during the crucial construction stages. The bending moment and displacement of the left tunnel is strongly related to the unloading effects and displacement of surrounding soils, which can be alleviated by means of proper improvement of excavation sequence. Comparatively, longitudinally divided excavation is more effective in protecting the left tunnel than soil improvement or a cut-off wall. This study is of certain reference value for protecting metro tunnels adjacent excavation in soft soils.

Learning curves of a resident surgeon performing transobturator tape procedures for stress urinary incontinence

ObjectiveTo evaluate the number of procedures necessary for an untrained resident surgeon to learn transobturator tension-free vaginal tape (TVT-O) procedures for treatment of stress urinary incontinence (SUI). MethodsA prospective study was performed among patients aged 18–75 years who underwent TVT-O procedures at a center in Rome, Italy, between March 2, 2009, and November 30, 2012. The TVT-O procedure was performed by a right-handed resident surgeon working under the supervision of an expert surgeon. Total and partial operative times were recorded. ResultsAmong 18 patients included in analysis, the mean operative time was 22.2minutes (range 7–44). All total operative times fell within the confidence interval after the 10th procedure, with a difference between the mean times recorded in the first nine and the last eight procedures (29.5 vs 13.1minutes; P<0.001). The resident surgeon required nine procedures to learn right tunneling and 13 to learn left tunneling. ConclusionTen procedures were required for a resident surgeon to learn TVT-O procedures for SUI.

Path selection by the termite Reticulitermes speratus kyushuensis (Isoptera: Rhinotermitidae) at a bifurcation node of Y-shaped tunnel

Subterranean termites excavate complicated tunnel networks for foraging below the ground. During foraging activity, termites often encounter many bifurcation nodes generated by the tunnel branching or the tunnel–tunnel interaction. Path selection by termites at the node is likely to affect the foraging efficiency because depending on their selection, the traveling distance from food resources to the nest can vary significantly. To understand the selection mechanism, we artificially constructed Y-shaped tunnels in small arenas and observed the termite behavior at the bifurcation node (i.e. the intersection of the tunnel). At the bifurcation node, the right side tunnel forms 45° with respect to the straight tunnel that a termite advances, while the left side tunnel forms the angle of θ (=5°, 15°, 30°, and 45°). The experimental results showed that the path selection strongly depends on which termite's antenna touching is first made on the tunnel wall at the bifurcation node. The left (or right) antenna touching tended to cause the right (or left) tunnel selection. As the value of θ increased, the tendency for the left selection ratio decreased. The bias of the advancing termites towards the left (or right) enhanced the tendency of the selection of the left (or right) tunnel but did not affect the spent time of the termites to pass through the node. The results were understood by the location relationship between the advancing termites and the tunnel wall. We briefly discussed the meaning of our finding in relation to the foraging efficiency.

U-Pb dating of speleogenetic dolomite: A new sulfuric acid speleogenesis chronometer

The 1100-meter Big Room elevation level of Carlsbad Cavern, New Mexico USA, formed 4 Ma by hypogenic sulfuric acid speleogenesis (SAS). The age of the Big Room level of 4.0 ± 0.2 Ma was previously determined by dating alunite, a byproduct of speleogenesis, using the 40Ar/39Ar method. Duplication of these results is possible by radiometric dating of other byproducts interpreted to be speleogenetic (a byproduct of speleogenesis) such as calcite and dolomite in certain settings. XRD and TEM analyses of sample 94044, a piece of crust collected within the Big Room level of SAS just below Left Hand Tunnel indicate that this dolomite sample we interpret to be speleogenetic is as well-ordered crystallographically as the Permian bedrock dolomite, possibly reflecting its SAS origin. Three U-Pb analyses were performed on subsamples A1, A2, and A3 of sample 94044, and two, A1 & A2, produced out-of-secular equilibrium results due to the presence of authigenic quartz and/or later re-distribution of uranium in the dolomite crust, which prevented the calculation of an isochron age. Because subsample 94044-A3 exhibited δ234U and 230Th/238U values consistent with secular equilibrium, we were able to generate a 238U/204Pb-206Pb/204Pb model age of 4.1 ± 1.3 Ma on the dolomite crust (94044) that we interpret to be reliable. The 4.1 Ma age of the speleogenetic dolomite crust agrees with the 4 Ma 40Ar/39Ar age for the timing of speleogenesis of the Big Room level. While 40Ar/39Ar-dating of speleogenetic alunite- and jarosite-group minerals remains the primary way to determine absolute timing of hypogenic SAS, here we demonstrate that U-Pb dating of speleogenetic dolomite can be used to compliment or independently measure the timing of SAS. This method of dating SAS could be applicable in caves where the more soluble SAS-indicator minerals such as gypsum, alunite, and jarosite have been removed.

Carpal Tunnel Syndrome and Trigger Fingers in a Patient with Rheumatoid Arthritis and Systemic Lupus Erythematosus: Case Example

Abstract Causation analysis involves determining what conditions are related to a compensable injury or illness; apportionment is the allocation of responsibility among two or more probable causes; and assessing impairment is based on the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides). These three are separate activities, but sometimes all three must be addressed in a single evaluation and may be required for a specified jurisdiction (eg, California). Evaluators thus must ask if jurisdictional issues dictate or influence the approach to causation and apportionment; which edition of the AMA Guides to use; and how to approach causation and apportionment in the present case example: A 63-year-old woman with rheumatoid arthritis and systemic lupus erythematosus is assessed by an orthopedic surgeon who is the agreed medical evaluator (AME). In addition to her pre-existing rheumatoid arthritis and lupus, the individual also had Sjogren's syndrome, osteoarthritis, degenerative disc disease, left carpal tunnel syndrome, osteopenia, and obesity. She has undergone multiple surgical procedures, and treatment for her collagen vascular disease includes leflunomide (immunosuppressant), hydroxychloroquine, and prednisone. In this case, impairments were not the result of “cumulative trauma” but rather were secondary to underlying chronic inflammatory disease, and her occupational permanent impairment rating accordingly would be zero.

Numerical analysis of water flow characteristics after inrushing from the tunnel floor in process of karst tunnel excavation

In order to investigate water flow characteristics after inrushing in process of karst tunnel excavation, numerical simulations for five case studies of water inrush from the tunnel floor are carried out by using the FLUENT software on the background of Qiyueshan high risk karst tunnel. Firstly, the velocity-distance curves and pressure-distance curves are drawn by selecting a series of probing lines in a plane. Then, the variation characteristics of velocity and pressure are analyzed and the respective optimized escape routes are made. Finally, water flow characteristics after inrushing from the tunnel floor are discussed and summarized by comparing case studies under the conditions of different water-inrush positions and excavation situations. The results show that: (1) Tunnel constructors should first move to the tunnel side wall and then escape quickly when water inrush happens. (2) Tunnel constructors must not stay at the intersection area of the cross passage and tunnels when escaping. (3) When water inrush from floor happens in the left tunnel, if tunnel constructors meet the cross passage during escaping, they should pass through it rapidly, turn to the right tunnel and run to the entrance. (4) When water inrush from floor happens in the left tunnel, if there is not enough time to escape, tunnel constructors can run to the trolley and other equipment in the vicinity of the right tunnel working face. In addition, some rescuing equipment can be set up at the high location of the cross passage. (5) When water inrush from floor happens in the cross passage, tunnel constructors should move to the tunnel side wall quickly, turn to the tunnel without water inrush and run to the entrance. (6) When water inrush from floor happens in the cross passage, if there is not enough time to escape, tunnel constructors can run to the trolley and other equipment near by the left or the right tunnel working face. The results are of important practical significance and engineering value to ensure the safety of tunnel construction.

Pentobarbital Toxicity after Self-Administration of Euthasol Veterinary Euthanasia Medication.

Suicide attempt via sodium pentobarbital is uncommon. A 48-year-old woman with a history of depression and prior suicide attempt was found unresponsive by her veterinarian spouse near a syringe containing pink solution. Upon EMS' arrival, the patient was experiencing apnea, hypoxemia, and miotic pupils; her blood glucose level measured 73 mg/dL. She was bradycardic and administered atropine with transient improvement in heart rate and transported to an emergency department; 2 mg of intravenous naloxone was administered without effect. She was endotracheally intubated via rapid sequence intubation. Rapid urine drug screening detected both benzodiazepines and barbiturates. The patient was transferred to an intensive care unit where she demonstrated a nearly absent radial pulse. Emergent fasciotomy to the left forearm and carpal tunnel was performed for acute compartment syndrome; “Euthasol” had been self-administered into the antecubital fossa. Expanded toxicological analysis via liquid chromatography/mass spectroscopy detected caffeine, atropine, 7-aminoclonazepam, phenytoin, citalopram, and naproxen. The patient's coma resolved over 48 hours and she was successfully extubated without complication. Emergency physicians must closely monitor patients exposed to veterinary euthanasia agents who develop central nervous system and respiratory depression, hypothermia, bradycardia, hypotension, or skin injury. Consultation with a regional poison center and medical toxicologist is recommended.

Medial Ankle Mass in a Division-I Volleyball Player

HISTORY: 19 year old NCAA Division-I Men’s Volleyball player with PMH of multiple left ankle sprains presented with 5 days of left medial ankle pain with swelling. He developed mild pain without audible pop or snap while doing leg presses but was able to finish. He then gradually developed numbness in the plantar left 2nd, 3rd, and 4th toes spreading into the metatarsals. The ankle pain improved spontaneously over 2 days but numbness persisted. Ice, NSAIDs, and mobilization exercises provided little relief. PHYSICAL EXAMINATION: He was afebrile with stable vital signs. His gait was normal. There was a 15x5mm fluctuant mass without cyanosis or bruising in the left tarsal tunnel that was tender to palpation. Ankle and toes exhibited full range of motion, but there was mild weakness on plantarflexion of the left 2nd, 3rd, and 4th toes. Posterior tibialis and flexor hallucis longus strength were normal. Plantar left 2nd, 3rd, and 4th toe sensation to light touch were decreased. Dorsalis pedis pulse was full and intact but the posterior tibial pulse was difficult to palpate. Capillary refill of the toes was normal. Tinel’s test over the tarsal tunnel reproduced pain and exacerbated the numbness and tingling in the toes. DIFFERENTIAL DIAGNOSIS: 1. Aneurysm/Hematoma 2. Malignancy/Neoplasm 3. Accessory Soleus Strain 4. Tarsal Tunnel Syndrome 5. Posterior Tibialis Tear 6. Flexor Digitorum Longus Tear 7. Flexor Hallucis Longus Tear 8. Osteochondral Defect of the Ankle TEST AND RESULTS: MSK US: 19x6mm complex clotted hematoma in the tarsal tunnel with compression of the tibial nerve. Posterior tibialis, flexor digitorum longus, and flexor hallucis longus tendons were normal FINAL WORKING DIAGNOSIS: 1. Tarsal Tunnel Hematoma 2. Tarsal Tunnel Syndrome TREATMENT AND OUTCOMES: 1. He was treated with gentle range of motion exercises and warm compresses. 2. The hematoma and symptoms slowly resolved over 3 weeks. 3. He returned to volleyball 1 week after hematoma resolution without any issues.

Exploration and Grouting of Large-Scale Water Capsule in the Fault Fracture Zone of Yonglian Tunnel

A large-scale water capsule was formed after 8 times inrush of mud and water in Yonglian tunnel. The capsule seriously inhabited the construction of the tunnel. By combining with the geological conditions in tunnel site, the causes and characteristics of the water capsule were analyzed. Its spatial location and size were explorated by comprehensive exploration methods. In order to control the water capsule, the treatment scheme composed by full-face curtain grouting in left tunnel and decompression by drainage in right tunnel was made, and the composite and controlling grouting methods were proposed. The composite and controlling grouting technology was applied in the treatment. It was composed by grouting parameters selection, grouting material and technology optimization by means of numerical simulation, model experiment and SEM microscopic experiment. By means of the grouting effect examination methods including P-Q-t curve, examination holes, surrounding rock deformation monitoring and excavation, the water capsule was proved to be treated successfully. The engineering case provides a reference for the similar engineering to some extent.

Case Report: Aortic Root Abscess with a Left Ventricular Outflow Tract Tunnel

Aortic root abscess is one of the dreaded complications of aortic valve infective endocarditis. It carries a very high morbidity and mortality. Early diagnosis and surgical treatment is the main key. Echocardiography aids in early detection of this complication. We report a 22 year old male patient of bicuspid aortic valve with native aortic valve endocarditis complicated with formation of aortic root abscess and severe aortic regurgitation(AR) through an Left ventricular outflow tract(LVOT) tunnel.

Smooth Blasting Construction Technology of Urban Shallow Subway Tunnel

The article combined the existing theory of smooth blasting and the in situ construction experience. From the viewpoint of smooth blasting in the practical engineering application, a research was initiated on how to put smooth blasting construction technology of urban shallow subway tunnel into use, based on the example of the construction of the small mileage segment of the left tunnel line of 2# shaft of Hai-pi tunnel interval of Qingdao Metro Line 2, which provides the reference for other section construction of Qingdao subway.

Research on Mechanical Characteristic of Weak Surrounding Rock Large Span Double and Multi-arch Tunnel Construction

According to construction scheme of some weak surrounding rock large span double and multi-arch tunnel works, finite element value simulation method is adopted to research weak surrounding rock deformation characteristic, anchor bolt mechanics characteristic, preliminary support and secondary lining structure mechanical characteristics, etc, and the research result shows that: repeatedly disturbance of excavation of middle pilot tunnel and subsequent supporting excavation shall easily reduce surrounding rock strength in the range of middle wall top and middle line of arch top of left and right pilot tunnels, therefore, prior to excavation of middle pilot tunnel, surrounding rock of tunnel top shall be pregrouting reinforced to improve integrated strength of surrounding rock of arch top, max. accumulated settlement displacement of tunnel is 19.45mm, max. horizontal convergence displacement of side wall of left and right tunnel is 9.71mm, max. vertical upheaval displacement of middle wall bottom is 8.82mm, above displacement can all be within controlled range satisfying design requirement; max. plastic zone vertical depth of upper side of left and right tunnel arch top is respectively 1.23m and 2.06m, inverted arch bottom plastic zone vertical depth is 2.74m and 3.37m, radial depth of middle plastic zone of side wall of left and right tunnel is respectively 0.87m and 1.73m, mutual impact range of spatial effect of tunnel face of left and right tunnel is 3 folds tunnel span. This research shall be referred to by similar tunnel design and construction.

Research on Mechanical Characteristic of Weak Surrounding Rock Large Span Double and Multi-Arch Tunnel Construction

According to construction scheme of some weak surrounding rock large span double and multi-arch tunnel works, finite element value simulation method is adopted to research weak surrounding rock deformation characteristic, anchor bolt mechanics characteristic, preliminary support and secondary lining structure mechanical characteristics, etc, and the research result shows that: repeatedly disturbance of excavation of middle pilot tunnel and subsequent supporting excavation shall easily reduce surrounding rock strength in the range of middle wall top and middle line of arch top of left and right pilot tunnels, therefore, prior to excavation of middle pilot tunnel, surrounding rock of tunnel top shall be pregrouting reinforced to improve integrated strength of surrounding rock of arch top, max. Accumulated settlement displacement of tunnel is 19.45 mm, max. Horizontal convergence displacement of side wall of left and right tunnel is 9.71 mm, max. Vertical upheaval displacement of middle wall bottom is 8.82 mm, above displacement can all be within controlled range satisfying design requirement; max. plastic zone vertical depth of upper side of left and right tunnel arch top is respectively 1.23 m and 2.06 m, inverted arch bottom plastic zone vertical depth is 2.74 m and 3.37 m, radial depth of middle plastic zone of side wall of left and right tunnel is respectively 0.87 m and 1.73 m, mutual impact range of spatial effect of tunnel face of left and right tunnel is 3 folds tunnel span. This research shall be referred to by similar Tunnel design and construction.

Numerical Simulation on Effect of Shield Tunnel Construction on Pipelines with 45* Skew Angle and Tunnel

Shield tunnel construction cause soil movement to harm the adjacent underground pipelines. This paper, taking Dalian Spring Street subway station as the background, uses the finite difference software to establish 3-D finite element analysis model to simulate the deformation of pipeline with 45* skew angle in the tunnel construction work. The results show: when the left tunnel push towards pipelines, due to the skew of the pipeline and tunnel, vertical displacement of pipelines is a certain shift to the left. When the right tunnel excavation is complete, the pipeline maximum settlement has a return to the center of the two tunnels. The settlement of pipeline is much bigger than horizontal displacement.

Surgical Repair of an Aortico-Left Ventricular Tunnel with Acute Infective Endocarditis

Aortic-left ventricular tunnel is a rare congenital cardiac anomaly, which always arises from the right coronary sinus and enters the left ventricle, occasionally the right ventricle and right atrium. However, aortic and left ventricular tunnel associated with infective endocarditis is rarely seen in literatures. Here, we present a case of aortic and left ventricular tunnel associated with infective endocarditis in a 47-year-old man.

The Prediction and Control Research on the Attenuation Law of Blasting Vibration Peak Velocity in Daiyuling Tunnel

In combination with field blasting vibration tests in Daiyuling 2# Tunnel, abundant field monitoring datum have been obtained, in order to predict the strength of blasting vibration and research the control problem about stability of surrounding rock. Through the evaluation on blasting affects of the first excavated tunnel when the last excavated tunnel in the initial stage is into tunnel hole, establish the relationship of blasting vibration disturbing degree both neighborhood tunnels to improve the accuracy. Acoustic testing technology has been adapted to test rock acoustic velocity with blasting from beginning to end. The experimental results show that: (1) rock has a larger effect on attenuation effect in the spread of seismic wave, and blasting is really damage the surrounding rock; (2) regression analysis with the formula reflecting correctly the real situation on the blasting stress wave attenuation; (3) compared with blasting vibration attenuation coefficient both the left tunnel and right tunnel, the blasting vibration damage in soft rock is more than in hard rock; (4) the most dangerous location caused by tunnel blasting excavation is the adjacent tunnel blasting face, and its velocity is 5.8845 cm/s, it is practical and feasible that the clear distance of neighborhood tunnels should keep in 21m.

Evaluation of Supporting Structure Stability on New Fault of Xuefengshan Tunnel Zk97+830

For Xuefengshan tunnel, supporting stability in the course of tunneling is analysed by use of changed parameters of construction and design, which is based on construction simulation of left tunnel in the fault. It was shown that tunnel structure can keep stability after advanced little pipe injection grouting is used and supporting parameters and excavation model are changed. It can provide scientific evidence for directing construction and ameliorating supporting parameters, and it can reduce loss which is resulted by heavy collapse because of incorrect support.

Transcatheter Device Closure of a Congenital Aortic-Left Atrial Tunnel

Rare cases of aortic-left atrial tunnel exist in the literature. This case report highlights the echocardiographic characterization of this vascular anomaly and provides the first description of an aortic-left atrial tunnel closed by interventional cardiac catheterization in a pediatric patient.

Three Dimensional Finite Element Analysis of Subway Shield Tunnel under Exsisting Bridge

One city subway shield tunnel under-passing an existing bridge is analyzed, using the method of the three dimensional finite element analysis to simulate the process of excavating the left and right tunnel to get the data of the subsidence, lateral, stress of the bridge, besides the reaction of the upper structure of the bridge when the shield machine thrusting ahead. The results of the study show that the overall settlement value of the pier is not big, but around piers on both sides, the maximum lateral come to 2.6 mm, and the maximum tension, compression stress of the bridge foundation increased by 1.07MPa and 0.4MPa, and arch structure in construction process stress adverse, it is suggested that we should reinforce the soil around the tunnel treatment to control the bridge foundation of uneven settlement, and at the same time, the process of closely monitor the situation of arch bridge.