• Journal of the Korean Society for Railway
• /
• v.17 no.1
• /
• pp.52-58
• /
• 2014

Plastic deformation of roadbed influences the stability and maintenance of concrete slab track. Long-term plastic deformation in a railway roadbed is generated primarily due to accumulated inelastic strains caused by repeated passing of trains. Prediction of cumulative plastic deformation is important in cost-effective maintenance of railway tracks as well as for the safe operation of trains. In this study, the vertical displacements in railway roadbeds with different thicknesses of reinforced roadbed were computed. Parameters of the power model for cumulative plastic strain were calibrated by using the data from triaxial tests and full-scale loading tests. Results of three-dimensional finite element analyses of standard roadbed sections provide us with design guidelines for the selection of the thickness of reinforced roadbed.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.141-144
• /
• 2008

Recently, railway has been pointed to the efficiency of transportation, rapid transit, and comfortable train ride. the construction of railway near the downtown area and station building are increasing for maximization of utilization and convenience. but the heavy of transportation and rapid transit lead to increase noise and vibration. the noise and vibration of railway may cause the civil appeal, decline in the serviceability and insufficiency of environmental standard. Therefore, the solution to avoid environmental matters becomes one of the most important factor in constructing railway. In this study, floating slab system which is one of the solution to avoid noise and vibration in railway has been introduced, and the concept of preliminary design and vibration absorber of floating slab system according to the isolator has been introduced.

• Journal of the Korean Society for Railway
• /
• v.18 no.4
• /
• pp.354-362
• /
• 2015

Since allowable settlement of concrete slab track is about 30mm, a lot of attention must be paid to the settlement of the earthwork (reinforced trackbed, upper subgrade, under subgrade) under the concrete track. To this end, more experimental data should be accumulated through tests for these materials. In this study, we evaluate the long-term settlement of reinforced trackbed and subgrade materials using factors such as repeated loading conditions, water content, and grain size distributions in a large triaxial test and a large oedometer test. In cases in which the performance of the reinforced trackbed layer meets the design criteria, the settlement caused by train load was considerably small. But, when the water content increases in the subgrade, unexpectedly large settlement might occur for certain grain size distributions of the subgrade materials.

• International Journal of Railway
• /
• v.7 no.1
• /
• pp.16-23
• /
• 2014

Reduction in railway-induced vibrations in urban areas is a very challenging task in railway transportation. Many mitigation measures can be considered and applied. Among these, a little attention has been paid to trenches. In this study, a numerical investigation on the effectiveness of in-filled trenches with pipes in reducing railway vibrations due to passing trains is presented. Particularly, a series of two-dimensional dynamic analysis was performed to model the behavior of ballasted railway track under harmonic load with ABAQUS software as a Finite Element method. In so doing, two types of in-filled trenches with pipes with steel and concrete materials have been investigated in this paper. In addition, effectiveness of pipes made of steel and concrete, filled with loose sand and clay in railway-induced vibration reduction has been assessed. The results point out that using in-filled trench with pipes does not effective a lot on railway-induced vibration reduction in comparison to other railway-induced vibration reduction methods. However, in-filled trenches with steel pipes are much more effective than in-filled trenches with concrete pipes. Moreover, filling pipes with loose sand and clay does not have any effect on vibration reduction efficiency of these in-filled trenches.

• Journal of the Korean Geosynthetics Society
• /
• v.15 no.1
• /
• pp.21-35
• /
• 2016

It is a current trend that the concrete track is applied for high speed railway. In the case of the railway embankment constructed on soft ground, the damage to concrete track which is sensitive to settlement such as distortion and deflection could be caused by very small amount of long term settlement. Pile Supported Embankment method can be considered as the effective method to control the residual settlement of the railway embankment on soft ground. The Geosynthetics is used inside of the embankment to maximize the arching effect transmitting the load of the embankment to the top of the piles. But, PHC piles that are generally used for bridge structures are also applied as the pile supporting the load of embankment concentrated by the effect of the Geosynthetics. That is very low efficiency in respect of pile material. So, in this study, the cast in place concrete pile was selected as the most suitable pile type for supporting the embankment by a case study and the optimum mixing condition of concrete using a by-product of industry was induced by performing the mixing designs and the compressive strength designs. And it is shown that the cast in place pile with the optimum mixing condition using the by-product of industry is 2.8 times more efficient than the PHC pile for the purpose of Pile Supported Embankment by the finite element analysis method.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.793-799
• /
• 2011

A comprehensive analysis of wheel force spectrum is conducted to provide the KTX safety evaluation with structural behaviour of Pre-Stressed Concrete (PSC) box bridge due to various high speeds. The wheel spectrum for KTX locomotive running over road and PSC bridge tracks is compared using irregular track responses with numerical models of 170m approach road track and 40m span length of PSC box bridge The high-speed railway locomotive is used as 38-degree of freedom system. Three displacements (vertical, lateral, and longitudinal) and three rotational components (pitching, rolling, and yawing) for one car-body and two bogies are considered in the 38-degree of freedom model. Three dimensional frame element of finite element method (FEM) is used to model of the simply supported PSC box bridge. The irregulation of rail-way is derived using the experiential spectrum density function under assumption of twelve level tracks conditions based on the normal probability procedure. The dynamic analyses by Runge-Kutta method which are able to analyze the high frequency wheel force spectrum. A dynamic behaviour of KTX due to high speeds until 450km/h developing speed with relative time is analysed and compared the characteristics running over the road and PSC box bridge tracks. Finally, the KTX integrated evaluation method of safety between high speed train and bridge is presented.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.127-132
• /
• 2004

The third double-track construction part of work, called Chung Ang Railroad line(Deok-So$\∼$Won-Ju) is in progress and the personal museum located 330m from the starting point of Pal-Dang Tunnel(length=4,470m) line in the canyon is to be effected by rock blasting during the tunnel excavation work, especially museum articles and building itself. This paper is the example of application suitable tunnel rock blasting pattern for excavation after the case study about the investigation and analysis of rock blasting noise pollution during tunnel excavation work. The museum is a three-story building, RC concrete structure and is located 17m from the top of the tunnel, in the center of the double-track line. Comparing estimate vibration frequency with site vibration one, it can be verified the reasonable rock blasting noise pollution as improving the application of tunnel excavation rock blasting pattern. The above pattern has been selected economically and effectively and applied to our construction field.

• Advances in Computational Design
• /
• v.8 no.1
• /
• pp.1-12
• /
• 2023

To consider the effects of the increasing speed of next-generation high-speed trains, the existing traffic safety code for railway bridges needs to be improved. This study suggests a numerical method of evaluating the new effects of this increasing speed on railway bridges. A prestressed concrete (PSC) box bridge with a 40 m span length on the Gyeongbu track sector is selected as a representative example of high-speed railway bridges in Korea. Numerical models considering the inertial mass forces of a 38-degree-of-freedom train and the interaction forces with the bridge as well as track irregularities are presented in detail. The vertical deflections and accelerations of the deck are calculated and compared to find the new effects on the bridge arising with increasing speed under simply and continuously supported boundary conditions. The ratios between the static and dynamic responses are calculated as the dynamic amplification factors (DAFs) under different running speeds to evaluate the traffic safety. The maximum deflection and acceleration caused by the running speed are indicated, and regression equations for predicting these quantities based on the speed are also proposed.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.12 no.3
• /
• pp.71-83
• /
• 2008

In this paper, the basic principle, the application and the limitation of Infrared thermography technique to detect defects in different kinds of concrete structures are reviewed. Considered are voids beneath the concrete surface with experiments, delamination between concrete surface and fiber reinforced polymer sheet, the deterioration of steel bars in reinforced concrete, surface defects in historical buildings, pavements, bridges, and railway track graves. As a result, we conclude that infrared thermography methods are useful for fast detecting defects; however, they are influenced by environmental factors, specially temperature. Therefore it is recommended to use the infrared thermography technique with other NDT equipments to expect better result.

• Steel and Composite Structures
• /
• v.36 no.4
• /
• pp.481-492
• /
• 2020

To study the rail mapped deformation caused by the pier settlement of simply - supported bridges with China Railway Track System III (CRTS III) slab ballastless track (SBT) system under the mode of non-longitudinal connection ballastless track slab, this study derived an analytical solution to the mapped relationships between pier settlement and rail deformation based on the interlayer interaction mechanism of rail-pier and principle of stationary potential energy. The analytical calculation results were compared with the numerical results obtained by ANSYS finite element calculation, thus verifying the accuracy of analytical method. A parameter analysis was conducted on the key factors in rail mapped deformation such as pier settlement, fastener stiffness, and self-compacting concrete (SCC) stiffness of filling layer. The results indicate that rail deformation is approximately proportional to pier settlement. The smaller the fastener stiffness, the smoother the rail deformation curve and the longer the rail deformation area is. With the increase in the stiffness of SCC filling layer, the maximum positive deformation of rail gradually decreases, and the maximum negative deformation gradually increases. The deformation of rail caused by the pier settlement of common-span bridge structures will generate low-frequency excitation on high-speed trains.