scholarly journals Research on Vibration Law of Railway Tunnel Substructure under Different Axle Loads and Health Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Weibin Ma ◽  
Jinfei Chai ◽  
Zifen Li ◽  
Zili Han ◽  
Chaofeng Ma ◽  
...  
Keyword(s):  
Traffic Accidents ◽  
Good Condition ◽  
Health Conditions ◽  
Normal Operation ◽  
Comprehensive Treatment ◽  
Railway Tunnel ◽  
Basement Structure ◽  
Heavy Haul ◽  
Axle Loads ◽  
Freight Trucks

In this paper, 25-ton and 27-ton axle heavy trucks are used to carry out moving loading and dynamic real vehicle test on the cracked section, the intact section, and the repaired section of a railway tunnel foundation to test the dynamic performance of the tunnel basement structure with the change of axle loads and health conditions. By analyzing the influence law of dynamic response and fatigue life of heavy haul train under different basement conditions (intact, damaged, and repaired), the adaptability of railway tunnel equipment to freight trucks axle load is clarified. The results show that (1) the intact section of the tunnel can meet the normal operation of 25-ton and 27-ton axle load freight trains in good condition. (2) The normal operation of 25-ton and 27-ton axle load freight trucks is seriously affected by the cracked section of the tunnel. When the cracks in the tunnel basement are gradually hollowed out by groundwater, serious traffic accidents such as vehicle shaking and derailment are likely to occur. (3) The repaired section of the tunnel can meet the normal operation of 25-ton and 27-ton axle load freight trains after adopting the integrated comprehensive treatment of “Anchor-Injection-Drainage”. The research results will have reference significance for the condition assessment and disease treatment of the basement structure of the heavy haul railway tunnel.

scholarly journals Research on Dynamic Response Characteristics for Basement Structure of Heavy Haul Railway Tunnel with Defects

Mathematics ◽  
2021 ◽  
Vol 9 (22) ◽  
pp. 2893
Author(s):  
Jinfei Chai
Keyword(s):  
Constitutive Model ◽  
Dynamic Response ◽  
Principal Stress ◽  
Surrounding Rock ◽  
Railway Tunnel ◽  
Basement Structure ◽  
Measuring Point ◽  
Heavy Haul ◽  
Damage Constitutive Model ◽  
Heavy Haul Railway

Based on the basic principle of thermodynamics, an elastoplastic damage constitutive model of concrete is constructed in this paper. The model is realized and verified in FLAC3D, which provides a solid foundation for the study of dynamic response and fatigue damage to the base structure of a heavy haul railway tunnel. The dynamic response and damage distribution of the base structure of a heavy-duty railway tunnel with defects were numerically simulated by the concrete elastic-plastic damage constitutive model. Then, by analyzing the response characteristics of the tunnel basement structure under different surrounding rock softening degrees, different foundation suspension range and different foundation structure damage degree are determined. The results show the following: (1) The elastoplastic damage constitutive model of concrete can well describe the stress–strain relationship of materials, especially with the simulation results of post peak softening being in good agreement with the test results, and the simulation effect of the unloading–reloading process of the cyclic loading and unloading test also meet the requirements. (2) The initial stress field and dynamic response of the tunnel basement structure under the action of train vibration load are very different from the ideal state of the structure design when the surrounding rock of the base is softened, the base is suspended, or the basement structure is damaged. With the surrounding rock softening, basement hanging, or basement structure damage developing to a certain extent, the basement structure will be damaged. (3) The horizontal dynamic stress amplitude increases with the increase in the softening degree of the basement surrounding rock. The horizontal dynamic stress of the measuring point increases with the increase in the width of the hanging out area when the hanging out area is located directly below the loading line. When the degree of damage to the basement structure is aggravated, the horizontal dynamic tensile stress of each measuring point gradually decreases. (4) The maximum principal stress increment increases with the increase in the fracture degree of the basement structure, while the minimum principal stress increment decreases with the increase in the fracture degree of the basement structure, but the variation range of the large and minimum principal stress increments is small. The research results have important theoretical and practical significance for further analysis of the damage mechanism and control technology of the foundation structure of a heavy haul railway tunnel with defects.

Fatigue damage of a heavy-haul railway tunnel invert under a 33-tonne axle cyclic load

2019 ◽  
Vol 234 (5) ◽  
pp. 498-510
Author(s):  
Mingnian Wang ◽  
Yinting Zhao ◽  
Ziqiang Li ◽  
Dagang Liu ◽  
Li Yu
Keyword(s):  
Fatigue Damage ◽  
Cyclic Load ◽  
Large Scale ◽  
Surrounding Rock ◽  
Monitoring Methods ◽  
In Situ Tests ◽  
Railway Tunnel ◽  
Severe Fatigue ◽  
Heavy Haul ◽  
Heavy Haul Railway

The average cyclic load of heavy-haul railway trains is generally larger than that of a conventional mixed passenger and freight railway. This load leads to more severe fatigue damage to structures, including the concrete in a tunnel invert. This study focuses on the fatigue damage of a tunnel invert under a cyclic load of 33 tonnes. The damage classifications for the tunnel inverts are given based on field investigations. With large-scale in-situ tests on the Zhang-Tang Heavy-Haul Railway Tunnel, the pressure–time distributions for the additional dynamic stresses on the surface of the track-bed for various classes of the surrounding rock are proposed. They were subsequently validated against numerical simulation using the ANSYS Workbench module. Fatigue damage of the tunnel invert is demonstrated using both numerical and monitoring methods. It has been observed that the damage to the tunnel invert becomes severe and extensive if the quality of the surrounding rock degrades. Damage zones develop first at the top of the invert and then expand to a deeper position, depending on the rock grade.

Monitoring and Modeling of Landslide Processes on the Example of the City of Sochi

10.12737/342 ◽  
2013 ◽  
Vol 1 (1) ◽  
pp. 54-61
Author(s):  
Дарья Лейер ◽  
Сергей Маций ◽  
Sergey Maciy ◽  
Екатерина Безуглова ◽  
Ekaterina Bezuglova
Keyword(s):  
Retaining Wall ◽  
Normal Operation ◽  
Railway Tunnel ◽  
Recent Developments ◽  
Landslide Processes ◽  
Complex Monitoring ◽  
Protective Structures ◽  
Landslide Slope ◽  
Slope Condition ◽  
The City

ssible designing of reinforcement constructions. Yet some problems in simulation of landslide situation do occur. Options for using different soil models and calculation schemes are being analyzed on the example of protective structures construction for railway tunnel in the city of Sochi region. Simulation of landslide slope condition is carried out using geotechnical software Plaxis conside­ring different soil models (Linear Elastic и Mohr-Coulomb) and «reconstruction» of structures displacements. The value of retaining wall displacement alongside landslide slope as well as retaining walls sections inner movement is being estimated by results of complex monitoring. Recent developments were causing threat to the safety of building and construction works continuation at the railway and also to the normal operation of structures lower down the slope.

scholarly journals Assessing the Damaging Effects of Railway Dynamic Wheel Loads on Railway Foundations

2017 ◽  
Vol 2607 (1) ◽  
pp. 62-73 ◽  
Author(s):  
Michael P. N. Burrow ◽  
Jin Shi ◽  
Mohamed Wehbi ◽  
Gurmel S. Ghataora
Keyword(s):  
Good Condition ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Field Investigation ◽  
Dynamic Loads ◽  
Foundation Soil ◽  
Railway Line ◽  
Track Condition ◽  
Heavy Haul ◽  
Track Quality

Dynamic train wheel loads, which can be significantly greater than static loads, occur because of a variety of factors and unless they are properly considered in track structural design, significant unplanned maintenance and premature track failure may result. This is particularly so for traditional ballasted railways built on soft foundations, because although ballast lends itself to maintenance, it is often problematic and costly to repair damaged foundations. A novel rigorous analytical–numerical approach is described to predict and characterize, for the first time, the damage to which railway foundations can be subjected as a result of dynamic loads. The approach marries a sophisticated three-dimensional dynamic model of the train–track system incorporating vertical track quality, foundation soil distress models, statistical analysis methods, and results of field investigation. The resulting analyses demonstrate that the magnitudes and distributions of dynamic loads are a function of train speed and track quality, and that specific locations experience significantly higher amounts of damage, which can lead to a variety of track faults. The approach is illustrated via a study of a heavy haul railway line in China where the wheel loads and tonnage carried are set to increase significantly. Findings from the study suggest that the thickness of the ballasted layer would need to increase by over 20% to prevent premature foundation failure provided that the track is maintained in good condition, and by significantly more should the track condition be allowed to deteriorate.

scholarly journals KONDISI TERUMBU KARANG PULAU MANTEHAGE KABUPATEN MINAHASA UTARA PROVINSI SULAWESI UTARA

2019 ◽  
Vol 7 (3) ◽  
pp. 208
Author(s):  
Ardy Kase ◽  
Indri Manembu ◽  
Joshian Schaduw
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Anthropogenic Activities ◽  
Good Condition ◽  
Digital Camera ◽  
Health Conditions ◽  
Point Count ◽  
Lack Of Information ◽  
Reef Health ◽  
Moderate Condition

Coral reefs are coastal ecosystems with the highest level of diversity. Corals are invertebrates that are included in the Phylum Coelenterata (hollow animal) or Cnidaria. Whereas coral reefs are a collection of millions of polyps. Natural phenomena and various anthropogenic activities threaten the health and presence of Mantehage Island coral reefs and the lack of information about the health conditions of coral reefs on Mantehage Island. The purpose of this study is to determine the condition of coral reefs andto  provide baselines data on Mantehage Island. Data collection was done by using UPT  method (Underwater Photo Transect). Underwater Photo Transect carried out by underwater shooting using a digital camera that was shielded (housing). Image analysis were done using the CPCe software (Coral Point Count with Excel extensions). The results of coral reef health conditions at four stations on Mantehage Island shows, coral reef cover at each station as follows, station 1 (one) 53.00% were in good condition, station 2 (two) 25.40% were in a moderate condition, station 3 (three) 16.49% were in poor condition, and station 4 (four) 42.07% were in a moderate condition. From the four stations, the condition of Mantehage Island's coral reefs were in the moderate category with a percentage of 34.24%.Keywords:. Mantehage Island, Terumbu Karang, UPT, CPCe

scholarly journals Good condition of pavement as the key to the normal operation of the building

2016 ◽  
Vol 4 ◽  
pp. 15-20
Author(s):  
Matveev P.S. ◽  
Grigoreva G.N. ◽  
Igokhina E.O.
Keyword(s):  
Good Condition ◽  
Normal Operation ◽  
Safe Operation ◽  
Normative Documents ◽  
Decorative Element ◽  
Blind Area ◽  
Definition Of ◽  
Design Construction

Examines the role of the pavement for key in the safe operation of the building. Despite the fact that the blind area is an intrinsic part of any building, many in the Pro-the design, construction and operation don't care, considering it a kind of architectural decorative element, "path" around the building that are needed in order to safely move through the area. Interestingly, the concept of "blind area" meets-Xia in many normative documents, but the official definition of this term is missing. The conclusion is poly aprons in the work of bearing structures of the building. Correct-ing the condition of pavement is the key to the normal operation of the building.

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