• Earthquakes and Structures
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• 제22권6호
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• pp.625-635
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• 2022

High-rise buildings (HRBs) are considered one of the most common structures nowadays due to the population growth, especially in crowded towns. The lack of land in crowded cities has led to the convergence of the HRBs and the absence of any gaps between them, especially in lands with weak soil (e.g., liquefaction-prone soil), but then during earthquakes, these structures may be exposed to the risk of collision between them due to the large increase in the horizontal displacements, which may be destructive in some cases to the one or both of these adjacent buildings. To evaluate methods of reducing the risk of collision between adjacent twin HRBs, this research investigates three vibration control methods to reduce the risk of collision due to five different earthquakes for the case of two adjacent reinforced concrete (RC) twin high-rise buildings of 15 floors height without gap distance between them, founded on raft foundation supported on piles inside a liquefaction-prone soil. Contact pounding elements between the two buildings (distributed at all floor levels and at the raft foundation level) are used to make the impact strength between the two buildings realistic. The mitigation methods investigated are the base isolation, the tuned mass damper (TMD) method (using traditional TMDs), and the pounding tuned mass damper (PTMD) method (using PTMDs connected between the two buildings). The results show that the PTMD method between the two adjacent RC twin high-rise buildings is more efficient than the other two methods in mitigating the earthquake-induced pounding risk.

• 한국지반공학회논문집
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• 제34권6호
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• pp.25-36
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• 2018

지반의 액상화는 지진 피해의 대표적인 형태 중 하나이다. 이는 막대한 인적 경제적 피해를 줄 수 있는 현상으로, 지반구조물의 설계 전 필수적으로 검토해야 하는 대상이다. 본 연구에서는 하천 제방을 대상으로 임의의 지진 규모와 수위에서 액상화에 대한 실용적인 복합재해 취약도 곡면 작성법을 제시하였다. 지반의 파괴 정도를 나타내는 액상화 가능 지수(LPI)로 제방의 액상화에 대한 한계상태를 정의하였다. 지반 물성치의 불확실성을 고려하기 위해 Monte Carlo Simulation 기반의 확률론적 해석을 수행하였고, 해석 결과를 바탕으로 임의 수준의 수위와 지진 규모에 대하여 액상화에 의한 파괴확률을 나타내는 3차원의 취약도 곡면을 작성하였다. 작성된 복합재해 취약도 곡면은 홍수 및 지진에 대한 제방의 안전성 평가와 취약지역에 대한 위험도 평가에 사용될 수 있다.

• Geomechanics and Engineering
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• 제37권2호
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• pp.189-195
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• 2024

Buried pipelines can be classified as continuous and segmented pipelines. These infrastructures can be damaged either by ground movement or by seismic wave propagation during an earthquake. Permanent ground deformations (PGD) include surface faulting, liquefaction-induced lateral spreading and landslide. Liquefaction is a major problem for both superstructures and infrastructures. Buyukcekmece lake zone, which is the studied region in this paper, is a liquefaction prone area located near the North Anatolian Fault Line. It is an active fault line in Turkey and a major earthquake with a magnitude of around 7.5 is expected in this investigated region in Istanbul. It is planned to be constructed a new 12" steel natural gas pipeline from one side of the lake to the other side. In this study, this case has been examined in terms of two different support conditions. Firstly, it has been defined as a beam in liquefied soil and has built-in supports at both ends. In the other approach, this case has been modeled as a beam in liquefied soil and has vertical elastic pinned supports at both ends. These models have been examined and some solution proposals have been produced according to the obtained results. In this study, based on this sample, it is aimed to determine the behaviors of buried continuous pipelines subject to liquefaction effects in terms of buoyancy.

• Geomechanics and Engineering
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• 제36권5호
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• pp.455-464
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• 2024

Seismic movements have varying effects on structures based on characteristics of local site. During an earthquake, weak soils are susceptible to damage due to amplified wave amplitudes. Soil-structure interaction issue has garnered increased attention in Türkiye, after devastating earthquakes in Kocaeli Gölcük (1999), Izmir (2020), Kahramanmaraş Pazarcık and Elbistan (2023). Consequently, liquefaction potential has been investigated in detail for different regions of Türkiye, mainly with available field test results. Çankırı, a city located close to North Anatolian Fault, is mainly built on alluvium, which is prone to liquefaction. However, no study on liquefaction hazard has been conducted thus far. In this study, groundwater level map, SPT map, and liquefaction risk map have been generated using Geographical Information System (GIS) for the Buğday Pazarı District of Çankırı province. Site investigations studies previously performed for 47 parcels (76 boreholes) were used within the scope of this study. The liquefaction assessment was conducted using Seed and Idriss's (1971) simplified method and the visualization of areas susceptible to liquefaction risk has been accomplished. The results of this study have been compared with the City Council's precautionary map which is currently in use. As a result of this study, it is recommended that minimum depth of boreholes in the region should be at least 30m and adequate number of laboratory tests particularly in liquefiable areas should be performed. Another important recommendation for the region is that detailed investigation should be performed by local authorities since findings of this study differ from currently used precautionary map.

• Geomechanics and Engineering
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• 제8권5호
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• pp.663-674
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• 2015

Many seismically vulnerable regions in India and worldwide are located on deep soil deposits which extend to several hundred meters of depth. It has been well recognized that the earthquake shaking is altered by geological conditions at the location of building. As seismic waves propagates through uppermost layers of soil and rock, these layers serve as filter and they can increase the duration and amplitude of earthquake motion within narrow frequency bands. The amplification of these waves is largely controlled by mechanical properties of these layers, which are function of their stiffness and damping. Stiffness and damping are further influenced by soil type and thickness. In the current study, an attempt has been made to study the seismic site response of deep soils. Three hypothetical homogeneous soil models (e.g., soft soil, medium soil and hard soil) lying on bedrock are considered. Depth of half space is varied from 30 m to 2,000 m in this study. Controlled synthetic motions are used as input base motion. One dimensional equivalent linear ground response analyses are carried out using a computer package DEEPSOIL. Conventional approach of analysing up to 30 m depth has been found to be inadequate for deep soil sites. PGA values are observed to be higher for deeper soil profiles as compared to shallow soil profiles indicating that deeper soil profiles are more prone to liquefaction and other related seismic hazards under earthquake ground shaking. The study recommends to deal the deeper soil sections more carefully for estimating the amplification factors for seismic hazard assessment at the surface.