• Earthquakes and Structures
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• 제22권3호
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• pp.277-287
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• 2022

The ancient underground cities are a collection of self-supporting spaces that have been manually excavated in the soil or rock in the past. Because these structures have a very high cultural value due to their age, the study of their stability under the influence of natural hazards, such as earthquakes, is very important. In this research, while introducing the underground city of Ouyi Nushabad located in the center of Iran as one of the largest man-made underground cities of the old world, the analysis of dynamic stability is performed. For this purpose, the dynamic stress-displacement analysis has been performed through numerical modeling using the finite element software PLAXIS. At this stage, by simulating the Khorgo earthquake as one of the large-scale earthquakes that occurred in Iran, with a magnitude of 6.9 on the Richter scale, dynamic analysis by time history method has been performed on three selected sections of underground spaces. This study shows that the maximum amount of horizontal and vertical dynamic displacement is 12.9 cm and 17.7 cm, respectively, which was obtained in section 2. The comparison of the results shows that by increasing the cross-sectional area of the excavation, especially the distance between the roof and the floor, in addition to increasing the amount of horizontal and vertical dynamic displacement, the obtained maximum acceleration is intensified compared to the mapping acceleration applied to the model floor. Therefore, preventive actions should be taken to stabilize the excavations in order to prevent damage caused by a possible earthquake.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.477-484
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• 2000

Earthquake response analyses are conducted for the investigation of the ground shaking during the 1995 Hyogoken-nambu earthquake. Port Island a man made island with about 8{{{{ KAPPA m^2 }} area is chosen for this purpose Because earthquake measurement with vertical array was conducted there. Strain dependent characteristics of soil can be modeled well into Hardin-Drnevich Model. Four analyses are conducted : total stress analysis by equivalent linear method non-linear method. and two effective stress analyses. All analyses except equivalent linear analysis show fairy good agreement with observed record mainly because the non-linear behavior of Holocene clay layer has predominant effect on the behavior of fill, However detailed investigation show that effective stress analyses give much better prediction than total stress analyses.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1001-1006
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• 2004

Railroad disasters are frequently occurred by man-made causes or natural causes. In general, man-made causes are illegal construction practices, deterioration with the lapse of time and railroad crossing accidents, and natural causes are rainfall. snow, wind, earthquake, etc. Of cause, railroad disasters by man-made causes are prevented from keeping the safety principle, constructing multi-level crossing, securing enough men of ability and financial resources and making a thorough check using equipments with high capacity. And railroad disasters by natural causes are also minimized by construction of disaster prevention facilities, introduction and operation of general disaster prevention system and reasonable train passage control. Therefore, to setup the criterion of train passage control for train safety at railroad bridge under heavy rainfall, risky factors, national and oversea criteria under such circumstances are reviewed and a scheme to setup the criterion is suggested.

• 자원환경지질
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• 제19권4호
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• pp.297-304
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• 1986

Earthquake disaster is dependent upon both site intensity and strength of structures. The higher the strength, structures become more safe, which in turn increases the construction cost. Therefore, it is necessary to decide an optimum design intensity in which the safety is balanced with the cost. Such an optimum design intensity for major man-made structures in Korea is determined in the present study from a simulation model as follows. 1) Hypothetical earthquake time series are generated from the probability distribution to represent appropriately the seismicity of Korea. 2) The strength of structures constructed with a certain design intensity is assumed to exponentially decrease with the elapsed time. The construction cost is also expressed as a function of design intensity. 3) Comparing the seismic intensity generated from the earthquake time series with the strength of structures, the safety of structures is examined. Then the time until the structure is damaged by an earthquake is obtained within the designed life time. 4) The above simulation is iterated several hundred times and hence the mean life time of structures having a certain design intensity is obtained. 5) After all, the optimum design intensity to minimize the annual mean loss, the ratio of construction cost to mean life time, is estimated. The major conclusions obtained from the above simulation model are as follows. 1) Depending upon the designed life time ($T_p$), the optimum design intensities are appeared to be 0. 05-0. 10g for $T_p=50yr$ and 0. 08-0.13g for $T_p=100yr$. 2) According to the sensitivity analysis, the optimum design intensity increases with the rapid strength decrease of structure and decreases with the increase of initial construction cost.

• 화약ㆍ발파
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• 제27권2호
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• pp.48-55
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• 2009

지진 발생시 진앙 추적에 필요한 지각구조 특성 규명과정에서는 인공지진을 발생시킬 필요가 있다. 이런 정도의 큰 지반진동은 대규모 시추공 발파를 통해 발생시킬 수 있으나 이와 같은 대규모 발파는 대부분 주변에 대한 환경적인 악영향을 미치게 된다. 이런 맥락에서 시추공 시험발파를 통해 발파장소 주변의 다양한 구조물에 영향이 없는 최대 장약량을 결정하였다. 시험발파에서는 젤라틴 다이너마이트 400kg을 사용하였다. 시험 결과 측정된 자료로부터 지반진동 수준에 대한 예측식을 유도하였다. 주거용 구조물에 대한 지반진동 허용수준을 3.0mm/s로 설정하였을 때 발파장소 부근의 군용 구조물을 고려한 경우에는 사용 가능한 최대 장약량이 677kg으로 나타났다. 하지만 군용건물들을 고려하지 않고 인근부락의 오래된 건물들을 기준으로 할 때는 최대 2100kg의 폭약을 사용할 수 있는 것으로 나타났다.

• 지질공학
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• 제10권2호
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• pp.98-112
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• 2000

지진자료를 분석해 지진기록으로부터 산업현장에서 발생하는 인공지진을 식별하여 정확한 지진 카타로그를 제공하는 것은 지진연구에서 가장 기초적인 과정이지만 또한 매우 중요한 과제이다. 특히 지진계에 기록된 지진자료 만으로 이를 식별하는 것은 매우 어려운 관계로 선진국에서는 수십 년 전부터 많은 연구가 수행되어 오고 있다. 현재 국제사회에서 발효를 앞두고 있는 CTBT 체제에서 인공발파와 자연 지진의 식별은 외교 정책적인 면에서 매우 심각한 국제문제를 야기 시킬수 있다. 본 연구에서는 지진파 - 공중음파 관축소의 자료를 종합 분석하여 지진과 인공발파를 식별하는 방법을 추천코자 한다. 최극 한반도 및 주변해역에서 발생한 지진들의 분포는 남쪽에서는 서산-포항을 잇는 N60-70$^{\circ}$W 방향으로 진앙이 집중되며, 북쪽에서는 주로 평안도와 황해도에 집중된다. 1936년 이후 한반도 및 인근해역에서 발생한 비교적 큰 지진들(규모 4.5 이상) 14개의 메카니즘(mechanism)은 주로 수평이동단층(strike-slip faulting) 형태로 이는 이 지역에 작용하는 주 응력은 압축력임을 나타낸다. 이는 한반도 및 인근해역에 작용하는 응력장이 동쪽에서 유라시아판(Eurasian Plate) 밑으로 침강하는 태평양판(Pacific Plate)의 영향뿐만 아니라 남서쪽에서 충돌하는 인도판(Indian Plate)의 영향도 작용하는 것으로 판단된다.

• 한국지진공학회논문집
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• 제20권6호
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• pp.401-412
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• 2016

On Tuesday, January 17, 1995, an earthquake of magnitude 7.2 struck the Port of Kobe. In effect, the port was practically destroyed. After a hazard investigation, researchers reached a consensus to adopt a performance-based design in port and harbor structures in Japan. A residual displacement of geotechnical structures after an earthquake is one of the most important engineering demands in performance-based earthquake-resistant design. Thus, it is essential to provide reliable responses of geotechnical structures after an earthquake through various techniques. Today, a nonlinear explicit response history analysis(NERHA) of geotechnical structures is the most efficient way to achieve this goal. However, verification of the effective stress analysis, including post liquefaction behavior, is difficult to perform at a laboratory scale. This study aims to rigorously verify the NERHA by using well-defined field measurements, existing numerical tools, and constitutive models. The man-made, Port Island, in Kobe provides intensive hazard investigation data, strong motion records of 1995 Kobe earthquake, and sufficient engineering parameters of the soil. Two dimensional numerical analysis was conducted on the caisson quay wall section at Port Island subjected to the 1995 Kobe earthquake. The analysis result matches very well with the hazard investigation data. The NERHA procedure presented in this paper can be used in further studies to explain and examine the effects of other factors on the seismic behavior of gravity quay walls in liquefiable soil areas.

• 대한안전경영과학회지
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• 제13권1호
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• pp.1-9
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• 2011

It is a significant issue for several country including Korea, where the natural and the weather conditions are severe, to keep the safety against disasters which occur frequently every year, especially in urban region crowded with population. In order to implement suitable and effective measures against various disasters in such area, development of method for evaluation of disaster prevention performance based on various disaster risks and effective disaster damage mitigation technologies is independable. In this paper, methods for hazard evaluation, vulnerability evaluation and loss evaluation, and damage technologies are proposed targetting man-made disaster and natural one like flood, earthquake and tsunami and so on. The method proposed in this paper is based on the research of USA and Japan for man-made disaster and natural disaster. The proposed method will be developed in detail in four years during research period funded by government.

• 한국지진공학회논문집
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• 제27권2호
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• pp.77-82
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• 2023

The structural analysis module is an essential part of any integrated structural system. Diverse integrated systems today require, from the analysis module, efficient real-time responses to real-time input such as earthquake signals, extreme weather-related forces, and man-made accidents. An integrated system may also be for the entire life span of a civil structure conceived during the initial conception, developed throughout various design stages, effectively used in construction, and utilized during usage and maintenance. All these integrated systems' essential part is the structural analysis module, which must be automated and computationally efficient so that responses may be almost immediate. The finite element method is often used for structural analysis, and for automation, many effective finite element meshes must be automatically generated for a given analysis. A computationally efficient finite element mesh generation scheme based on the r-h method of mesh refinement using strain deviations from the values at the Gauss points as error estimates from the previous mesh is described. Shape factors are used to sort out overly distorted elements. A standard cantilever beam analyzed by four-node plane stress elements is used as an example to show the effectiveness of the automated algorithm for a time-domain dynamic analysis. Although recent developments in computer hardware and software have made many new applications in integrated structural systems possible, structural analysis still needs to be executed efficiently in real-time. The algorithm applies to diverse integrated systems, including nonlinear analyses and general dynamic problems in earthquake engineering.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.187-190
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• 2003

In order to apply a cyclic elasto-plastic and a viscoelastic-viscoplastic constitutive model to actual multi-layered ground conditions during large earthquake, numerica simulations were performed by a liquefaction analysis in the present study. From the liquefaction analysis, it was verified that the models can give a good description of the damping characteristics and liquefaction phenomena of ground accurately during large event which induces plastic deformation in large strain range.