• Proceedings of the KSR Conference
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• 2003.05a
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• pp.567-573
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• 2003

Korean High Speed Train (KHST) has been tested on high speed line in JungBu site since it was developed in 2002. The data acquisition system was developed to accomplish successfully this on-line test for proving the dynamic Performance of KHST. This system was consist of the personal computers based on National Instrument PXI modules and the test programs based on Labview 6i. This paper shows that this system is efficient to acquire the test data through the multi-channels connected the accelerometers which located in long distance places and flexible to change and add channels for data acquisition. The dynamic analysis of an on-line test is very complicate because the environmental conditions, as examples radius of curve, inclination of the track, tunnels, bridges, and so forth, and running conditions, as examples driving, braking, the number of working motors, and so forth, have an effect on the results. Therefor, the analysis method is important and this paper proposes the efficient procedure graphically, showing the proposed method simplify the accelerations of 5th bogie frame acquired during the on-line test for KHST.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.483-488
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• 2009

When a train enters into the tunnel with high speed, a compression wave generated inside the tunnel has been studied as a one-dimensional phenomenon. However, one-dimensional approach can't analyze 3-dimensional flow effect in the vicinity of the train body. In this research, so as to overcome this weak point, a prediction method of the wavefront of a compression wave using steady state solution has been used for the parametric study considering 3-dimensional effects of the interactions between trains and tunnels. The effective hood shapes were deduced in both cases of the train's entry into the tunnel on the single track and on a side of the double track. As a result, in case of the train's entry on a side of the double track, the increase of compression wave value propagated to the tunnel inside have appeared compared with the train's entry on the single track. Also, a horizontally convex elliptic hood shape is more effective at the train's entry on a side of the double track for the purpose of a decrease of wavefront gradient of a compression wave.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1454-1462
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• 2008

This paper is focused on the analysis of the noise and vibration measured near the wheelset of the high-speed trains using a time-varying frequency transform as a preliminary research of running monitoring. Due to the non-stationary characteristics, it is necessary to examine noise and vibration of the train with time-varying frequency transforms. In this paper, the short-time Fourier transform method is utilized - the stored data is localized by modulating with a window function, and Fourier transform is taken to each localized data. For the examination, the non-stationary noise and vibration of the high-speed train's wheelset are measured by using some microphones and accelerometers, and those signals are stored in a on-board data acquisition system. The non-stationary random signal analyses with the short-time Fourier transform are performed, and the result are classified as follows; auto-spectral density, cross-spectral density, frequency response, and coherence functions. From those functions, it is possible to observe the frequency characteristics of sleepers, switchers, tunnels, and steel bridges. Also, some distinct peaks, which are not dependent upon the train's speed, are identified from the results.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.2
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• pp.249-260
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• 2014

When a train enters the tunnel at high speed, the pressure wave occurs. When this pressure wave reaches at the exit of tunnel, some are either emitted to the outside or reflected in tunnel by the form of expansion wave. The wave emitted to the outside forms the impulsive pressure wave. This wave is called 'Micro Pressure Wave'. The micro pressure wave generates noise and vibration around a exit portal of tunnel. When it becomes worse, it causes anxiety for residents and damage to windows. Thus, it requires a counterplan and prediction about the micro pressure wave for high speed railway construction. In this paper, the effects of train head nose and tunnel portal shape were investigated by model test, measurement for the micro pressure wave at the operating tunnel as well as numerical analysis for the gradient of pressure wave in the tunnel. As results, a method for predicting the intensity of the micro pressure wave is suggested and then the intensity of the micro pressure wave is analyzed by the tunnel length and the cross-sectional area.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1781-1788
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• 2008

This report is the result of a basic experiment done on a mock-up tunnel, of what happens to the ventilated flow and fire driven flow inside a railway tunnel as the current inside the tunnel changes when an anti-smoke or a radio frequency invert control is installed. The duct used in this experiment is 10m in length, 0.5m in height and 0.25m in width and made of acrylic. An anti-smoke system with a motor that can produce current of 10m/sec maximum in order to create ventilated flow, has been installed. A honeycomb has been installed at the entrance of the duct to create a current flow that exists in tunnels. In order to create a ventilated flow, a current of 4m/s, 6m/s and 8m/s were generated using the anti-smoke system, as the study of current developed. A Hot-wire(TSI) and Pressure sensor(ENDEVCO) was installed in the duct, 1m apart, as the measurement of current and pressure went on. The current and pressure were automatically measured through the Lap View program and PC; the current flow in the mock-up tunnel generated by the honeycomb has been analyzed the pressure distribution and pressure drop has been analyzed.

• Journal of the Korean GEO-environmental Society
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• v.24 no.10
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• pp.5-13
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• 2023

With the recent increase in development projects centered on urban areas, the construction of building structures is increasing in areas adjacent to the urban railway operation section. In this case, since ground vibration is generated by the train in operation and affects the adjacent structure, the building structure needs appropriate vibration reduction against train vibration generated at the adjacent location from the desing phase. However, the vibration levels calculated vary depending on the train vibration evaluation method, which means that the implementation of vibration reduction may vary depending on the train vibration evaluation method. Therefore, this study calculated the vibration level according to ground conditions, tunnel depth and separation distance between vibration sources and adjacent structures using numerical analysis and train vibration evaluation methods, and compared them to designning phase. And the appropriate separation distance between the tunnel and the adjacent structure was evaluated by comparing the vibration level with the allowable standards. As a result of the study, the Ungar and Bender evaluation method is evaluated as the most appropriate among the train vibration evaluation methods, and the appropriate separation distance between the tunnel and the adjacent structure is evaluated to be more than 4.5D.

• The Journal of Engineering Geology
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• v.18 no.1
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• pp.55-68
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• 2008

At present underground structures such as road tunnels, railway tunnels, underground petroleum storages and radioactive waste storages are being constructed in numerous places in Korea. For the construction of underground structrues, it should be accounted for natural factors (geology, hydrogeology, soil, vegetation, topography and drainage patterns) and human-social factors (land use, urbanization, population, culture and transportation). Especially, hydrogeology should be regarded as an important factor for evaluating the safety of underground structures and their impact to groundwater system around the structures. This study aimed to recognize hydrogeological characteristics of shallow formations in the area from Dongrae crossway to Seo-Dong where 45 boreholes were drilled for the construction of Line-3 subway in Busan Megacity. Slug tests for unsaturated and saturated zones were conducted on 30 boreholes in the study area. From the result of the slug tests, it was identified that average zonal hydraulic conductivity in the unsaturated zone was higher than that in the saturated zone. Besides, the slug test result in the saturated zones may reflect hydraulic properties of the upper most part of the saturated zones.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.5
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• pp.1-9
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• 2024

Recently, the TBM tunnel construction method has been in the spotlight as tunnel excavation under urban areas such as the Metropolitan Rapid Transit (GTX) has been actively carried out. Although the construction cost of the TBM tunnel is high, it is relatively free from noise and vibration compared to the NATM tunnel method, so it is well known to be a suitable construction method for application to the lower part of urban areas. In particular, when the stratum passes through the shallow section, it can have a great impact on existing upper structures and obstacles, so accurate numerical analysis considering various variables is required when designing the TBM tunnel. Unlike other tunnel construction methods, TBM tunnels build linings by assembling factory-made segments. Unlike NATM tunnels, segment lining has connections between segments, so how to the connection status between segments is reflected can have a significant impact on securing the reliability of analysis results. Therefore, in this paper, a segment joint model(Janssen Model) was applied to the lining for seismic analysis of the TBM tunnel, and the tunnel's behavioral characteristics were analyzed after numerical analysis using nonlinear models according to urban railway seismic design standards.

• Tunnel and Underground Space
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• v.34 no.5
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• pp.461-476
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• 2024

As the paradigm of urban development has recently changed to development of underground space, the road tunnels and railway tunnels are increasing to relieve traffic congestion. This technical notes is related to the development of underground spaces using NATM (New Austrian Tunneling Method). Limitations of conventional 2D blasting pattern design method were analyzed, and BIM-based automatic design method was developed to overcome them. Since it was developed to facilitate modeling of all safety facilities along a alignment using coordinates and GIS data, it can overcome the limitations of the number of safety facilities that can be considered and time required for conventional design. In the conventional design, the results of borehole test blasting were used to predict the blasting impact. However, the developed technology is possible to recalculate by applying the measurement results obtained from actual tunnel blasting, enabling rapid re-evaluation of the blasting impact on all safety facilities during construction, leading economical design. As a result of applying it to GTX-A5 and 6 sites, it took about 5 minutes, which is 1/480 compared to the conventional design method. In addition, the construction cost was reduced by about 8 billion won/km and the period was reduced by about 41 days/km. It is expected to be used as technical basis for calculating the optimal blasting pattern in the BIM-based design and construction management process.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.3
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• pp.251-259
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• 2006

For the electrification of the existing railways, the security of the restriction boundary of building with mechanistic stability research on the antiquated tunnel must be accomplished essentially. If the tunnel don't secure its restriction boundary of building, the reconstruction based on improvement of tunnel alignment are generated and its surveying data are required. The precise surveying was conducted with the same coordinate system for three tunnels of Youngdong tramline, and the restriction boundary of building of the straight and curve section were analyzed effectively by acquiring the data of profile and cross section, profile rail-height, rail-grade, cross tunnel height, and restriction boundary of building. This study is presented for valuation data of the stability of the electrification design to construct and analyze restriction boundary of building, which compared with the drawing and its existing design using profile and cross section. After this, it is interoperable to increase the development of real-time monitoring system on the tunnel structures.