• Title/Summary/Keyword: induced ground

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A Study on the Vibration Protection Efficiency of EPS Wall Barrier with Centrifuge Model Tests (원심모형실험을 통한 EPS 차단벽의 방진효과에 관한 연구)

  • Lee, Kang-Il
    • Journal of the Korean Geotechnical Society
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    • v.22 no.10
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    • pp.101-110
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    • 2006
  • In general, environment-induced vibration propagates from the center of source to the destination through ground. In fact, the mechanism of wave propagation is highly dependent on the ground conditions, and various methods to protect structures from such a ground vibration have been proposed. The method of wall barrier has been frequently used to cut off ground vibration effectively. However, the capability of wall barrier may be affected by various factors like constituent material of it. Therefore, it is important to figure out appropriate material for the wall barrier. This study is focused on the effect of EPS on the vibration protection. Centrifuge model tests were performed. Two types of models such as a cylindrical and a rectangular wall were used. For the cylindrical type of wall, installation depth was changed, while the length of the wall varied fur the rectangular type to figure out the capability of vibration protection.

Model Tests on Deformation Behavior of Soft Ground Under Embankment (성토하부 연약지반의 변형거동에 관한 모형실험)

  • Lee, Kwang-Wu;Cho, Sam-Deok;Hong, Won-Pyo
    • Journal of the Korean Geotechnical Society
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    • v.25 no.5
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    • pp.17-28
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    • 2009
  • When embankments are constructed on soft clay deposit, unsymmetrical surcharges due to embankments may generate the excessive vertical settlement and lateral deformation of soft clay foundation. The excessive deformations in soft grounds cause not only stability problem of the embankment itself but also that of the adjacent structures. The objectives of this research are to study the deformational behavior of soft ground due to the embankment load with different loading and soil conditions. Five model tests are carried out with different test conditions. From the results of the model tests, it is concluded that the lateral displacement induced by the embankment load occurs in the range of two times of the embankment width from a toe. In addition, the relationship between loading rate, v, and the vertical settlement of the soft ground, ${\Delta}s$, and the lateral displacement at the toe of embankment, ${\Delta}y_m$, is investigated based on the model test results.

A Study of Variation of Wave-induced Stresses in a Seabed (파랑하중에 의한 해저지반의 응력변화에 대한 연구)

  • 장병욱;박영권;우철웅
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.38 no.1
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    • pp.79-89
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    • 1996
  • It is expected that the soil hehaviours in the seahed subjected to cyclic wave loads are much different from that on the ground Cyclic shear stresses developed below the ocean bed as a result of a passing wave train may progressively build up pore pressure in certain soils. Such build-up pore pressure may be developed dynamic behaviour such as liquefaction and significant deformation of the seabed. Currently available analytical and testing methods for the seabed subjected to cyclic wave loads are not general. The purpose of the study are to provide a test method in laboratory and to analyse the mechanism of wave-induced stresses and liquefactions potentials of the unsaturated silty marine sand. It is showed that the test set-up made especially for this study delivers exactly oscillatory wave pressures of the form of sine function. Laboratory test results defining the cyclic shear strength of the unsaturated porous medium that is homogenously sedimented. It is understood that the pore water pressure due to induced-waves is not accumulated as the wave number increases but reveals periodical change on the still water surface. The magnitude of the pore water pressure tends to be attenuated radically with a certain time lag under the action of both high and low waves as depth increases.

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Visible Assessment of Earthquake-induced Geotechnical Hazards by Adopting Integrated Geospatial Database in Coastal Facility Areas (복합 공간데이터베이스 적용을 통한 해안 시설영역 지진 유발 지반재해의 가시적 평가)

  • Kim, Han-Saem;Sun, Chang-Guk
    • Journal of the Earthquake Engineering Society of Korea
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    • v.20 no.3
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    • pp.171-180
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    • 2016
  • Earthquake event keeps increasing every year, and the recent cases of earthquake hazards invoke the necessity of seismic study in Korea, as geotechnical earthquake hazards, such as strong ground motion, liquefaction and landslides, are a significant threat to structures in industrial hub areas including coastal facilities. In this study, systemized framework of integrated assessment of earthquake-induced geotechnical hazard was established using advanced geospatial database. And a visible simulation of the framework was specifically conducted at two coastal facility areas in Incheon. First, the geospatial-grid information in the 3D domain were constructed with geostatistical interpolation method composed of multiple geospatial coverage mapping and 3D integration of geo-layer construction considering spatial outliers and geotechnical uncertainty. Second, the behavior of site-specific seismic responses were assessed by incorporating the depth to bedrock, mean shear wave velocity of the upper 30 m, and characteristic site period based on the geospatial-grid. Third, the normalized correlations between rock-outcrop accelerations and the maximum accelerations of each grid were determined considering the site-specific seismic response characteristics. Fourth, the potential damage due to liquefaction was estimated by combining the geospatial-grid and accelerations correlation grid based on the simplified liquefaction potential index evaluation method.

A Study on the Effective Surge Protection Method from Induced Lightning Surge to Improve Isolate Grounding to Common Grounding (낙뢰 Surge 방호를 위한, 독립접지를 공통접지로 개선하는 효율적인 방법에 대한 연구)

  • Woo, Jea-Wook
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2013.10a
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    • pp.215-218
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    • 2013
  • This paper proposes the effective method to improve the protection from induced lightning surge by making common grounding from individual grounding. Common grounding under equipotential principle is more effective than individual grounding for lightning surge protection, and so common grounding is indicated as international technical standard under the AC power supply system with neutral line. So, this paper is to propose the effective way of induced lightning surge protection method for currently installed power supply system which has no neutral grounded line and individual grounding which are weak for lightning surge protection. This proposal can improve the power supply system as has neutral line, and improve the grounding system to common grounding system. And also this paper proposes to make effective equipotential system with voltage variable shunting devices for lightning surge protection.

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Development and Shaking Table Tests of a Base Isolator for Controling Subway Train-Induced Vibration of a Steel Building (지하철 진동에 대한 철골건물 기초진동 절연장치의 개발 및 진동대 실험)

  • Kim, Jin-Koo;Song, Young-Hoon;Kwun, Hyong-Oh;Huh, Young
    • Journal of KSNVE
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    • v.7 no.5
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    • pp.789-796
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    • 1997
  • In this study a conventional rubber mount and a new form of base isolator made of steel spring coated with natural and articial rubber were manufactured and tested on a shaking table to investigate the capacity of reducing the vertical vibration of a building induced by subway train. The model structure used in the test is a 1/4 scaled steel structure, and a white noise input and train vibration records were used to check the effectiveness of the isolators. According to the results all three types of isolators turned out to perform effectively in reducing the acceleration and the natural rubber-coated one is ranked best among the isolators. However the vertical displacement of the model is increased due to the instolation of the bearings, and the safty against the lateral load induced by earthquake ground motion should be provided to be able to apply the system to the real buildings.

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A 45-Year-Old Man With Recurrent Dyspnea and Hemoptysis during Exercise: Exercise-Induced Pulmonary Hemorrhage/Edema

  • Kim, Dae Sung;Lee, Minhyeok;Kwon, Oh Jung;Jeong, Inbeom;Son, Ji Woong;Na, Moon Jun;Kwon, Sun Jung
    • Tuberculosis and Respiratory Diseases
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    • v.78 no.4
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    • pp.375-379
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    • 2015
  • A 45-year-old man presented with dyspnea and hemoptysis during exercise. A chest computed tomography (CT) revealed multifocal diffuse patchy ground glass opacity and interlobular septal thickening in both the lungs. Permeability pulmonary edema or pulmonary hemorrhage was suspected. Serologic studies for autoimmune disorders and vasculitis were negative. There was no laboratory evidence of coagulopathy, other hematopoietic disease or infectious disease. Considering correlation with exercise, we diagnosed exercise-induced pulmonary hemorrhage (EIPH) or exercise-induced pulmonary edema (EIPE). The patient was managed with antifibrinolytics, antibiotics, and antitussive agent. After a week, follow-up chest CT revealed completely resolved pulmonary hemorrhage. About 2 months after the first event, he visited again with dyspnea and hemoptysis during running. In the present study, we report a case of recurrent pulmonary hemorrhage after exercise.

Pharmacodynamic Interactions of Diazepam and Flumazenil on Cortical Eeg in Rats (흰쥐 대뇌피질의 뇌파에 대한 diazepam 및 flumazenil의 약력학적 상호작용)

  • 이만기
    • Biomolecules & Therapeutics
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    • v.7 no.3
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    • pp.242-248
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    • 1999
  • Diazepam, a benzodiazepine (BDZ) agonist, produces sedation and flumazenil, a BDZ antagonist, blocks these actions. The aim of this study was to examine the effects of BDZs on cortical electroencephalogram (EEG) in rats. The recording electrodes were implanted over the frontal and parietal cortices bilaterally, and the reference and ground electrodes over cerebellum under ketamine anesthesia. To assess the effects of diazepam and flumazenil, rats were injected with diazepam (1 mgHg, i.p.) and/or flumazenil ( 1 mg/kg, i.p.), and the EEG was recorded before and after drugs. Normal awake had theta peak in the spectrum and low amplitude waves, while normal sleep showed large amplitude of slow waves. The powers of delta, theta and alpha bands were increased during sleep compared with during awake. Diazepam reduced the mobility of the rat and induced sleep with intermittent fast spindles and large amplitude of slow activity, and it produced broad peak over betaL band and increased the power of gamma band, which were different from EEG patterns in normal sleep. Saline injection awakened rats and abolished fast spindles for a short period about 2-5 min from EEG pattern during diazepam-induced sleep. Flumazenil blocked both diazepam-induced sleep and decreased the slow activities of delta, theta, alpha and betaL, but not of gamma activity for about 10 min or more. This study may indicate that decrease in power of betaL and betaH bands can be used as the measure of central action of benzodiazepines, and that the EEG parameters of benzodiazepines have to be measured without control over the behavioral state by experimenter.

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A Case Study on the Stability Assessment of Structures by Blast-induced Vibration (발파진동에 대한 구조물 안정성 평가 - 지하비축기지 건설 사례)

  • Lee, Chung-In;Choi, Yong-Kun;Jong, Yong-Hun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.479-484
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    • 2005
  • The test blasts were carried out by detonating some single blastholes at two upper sites of the underground storage cavern the crude oil. One was performed at the entrance site of the construction tunnel and the other at the middle part of the underground storage cavern. Based on the blast-induced vibration measured by the test blasts, we suggested the propagation equations of blasting vibration that were capable of estimating the peak particle velocity. In addition, in order to assess the stability of the nearest ground storage tank, we did the frequency analysis and the response spectrum analysis with the particle velocity-time history and the particle acceleration-time history that were measured by the test blast carried out on the entrance site of the construction tunnel. In result, it was predicted that the displacement on the highest part of the tank shell was less than the allowable displacement.

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Time history analysis of a tensile fabric structure subjected to different seismic recordings

  • Valdes-Vazquez, Jesus G.;Garcia-Soto, Adrian D.;Chiumenti, Michele;Hernandez-Martinez, Alejandro
    • Earthquakes and Structures
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    • v.20 no.2
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    • pp.161-173
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    • 2021
  • The structural behavior of a tensile fabric structure, known as hypar, is investigated. Seismic-induced stresses in the fabric and axial forces in masts and cables are obtained using accelerograms recorded at different regions of the world. Time-history analysis using each recording are performed for the hypar by using finite element simulation. It is found that while the seismic stresses in the fabric are not critical for design, the seismic tensile forces in cables and the seismic compressive forces in masts should not be disregarded by designers. This is important, because the seismic design is usually not considered so relevant, as compared for instance with wind design, for these types ofstructures. The most relevant findings of this study are: 1) dynamic axial forces can have an increase of up to twice the static loading when the TFS is subjected to seismic demands, 2) large peak ground accelerations seem to be the key parameter for significant seismic-induced axial forces, but not clear trend is found to relate such forces with earthquakes and site characteristics and, 3) the inclusion or exclusion of the form-finding in the analysis procedure importantly affects results ofseismic stresses in the fabric, but not in the frame.