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On June 27, 1998, a moderate earthquake measuring 5.9 on the Richter scale struck the alluvial plains of Cukurova in the Adana-Ceyhan region of Turkey. The earthquake resulted in 145 deaths, about a thousand injuries and significant damage to more than ten thousand structures. The coincidence of the projected location of the release of energy along the earthquake fault with a very vulnerable geological surface formation (the thick alluvial deposits of Ceyhan River containing loose sand layers) resulted in liquefied sediments of substantial thickness and extensive areal distribution. Liquefaction associated ground deformations such as lateral spreading, flow failures, ground fissures and subsidence, sand boils, and slope failures were observed. This paper presents and analyses the geotechnical aspects of this earthquake with the main emphasis on the observed liquefaction and associated ground deformations, together with the earthquake characteristics. The observed liquefaction mechanisms provide valuable information on the seismic response of the alluvial soils covering most of the Cukurova plains, an area of industrial and agricultural importance with more than 2 million inhabitants. The observations from this earthquake also provide us with an opportunity to further improve our understanding of the observed phenomena and their effects that can be expected during other future earthquake events around the world. 相似文献
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Dynamic compaction (DC) has been widely used for a variety of soil types and conditions in coastal area. However, as the ground water table is near the ground surface, a significant increase of pore water pressure is noticed after each impact, which results in local liquefaction and limits further drop effect. Consequently, to obtain effective compaction effects on saturated soils, it is essential for the evaluation of the liquefaction responses of soil medium caused by DC to determine the time delay between the drops and prevent ‘rubbery soil’. In this study, a numerical investigation on the liquefaction responses of saturated granular soils during DC is carried out using a coupled hydro-mechanical model. The developed model considers all the stages of DC involved in impact stage and consolidation stage. A new cap model for simulations of high strain rate behaviors of soils under DC is incorporated in the coupled hydro-mechanical model. Verification of the proposed model is performed against the previous test data and analytical result. Then, a series of parametric studies have been performed to examine the effects of the tamping energy level, hammer radius and permeability on liquefaction responses of saturated granular soils at several stages of DC. The numerical results demonstrate that the dimension of liquefaction zone is driven by the tamping energy level rather than the permeability, and strain rate has a significant effect on soil responses in DC. 相似文献
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Aditya Saputra Christopher Gomez Ioannis Delikostidis Peyman Zawar-Reza Danang Sri Hadmoko Junun Sartohadi 《地球空间信息科学学报》2021,24(2):256-278
Yogyakarta is one of the large cities in Central Java, located on Java Island, Indonesia. The city, and the Pleret sub-district, where the study has taken place, is prone to earthquake hazards, because it is close to several seismically active zones, such as the Sunda Megathrust and the active fault known as the Opak Fault. Since a devastating earthquake of 2006, the population of the Pleret sub-district has increased significantly. Thus, the housing demand has increased, and so is the pace of low-cost housing that does not meet earthquake-safety requirements, and furthermore are often located on unstable slopes. The local alluvial material covering a jigsaw of unstable blocks and complex slope is conditions that can amplify the negative impacts of earthquakes. Within this context, this study is aiming to assess the multi-hazards and risks of earthquakes and related secondary hazards such as ground liquefaction, and coseismic landslides. To achieve this, we used geographic information systems and remote sensing methods supplemented with outcrop study and existing seismic data to derive shear-strain parameters. The results have revealed the presence of numerous uncharted active faults with movements visible from imagery and outcrops. show that the middle part of the study area has a complex geological structure, indicated by many unchartered faults in the outcrops. Using this newly mapped blocks combined with shear strain data, we reassessed the collapse probability of buildings that reach level >0.75 near the Opak River, in central Pleret sub-district. Classifying the buildings and from population distribution, we could determine that the highest risk was during nighttime as the buildings susceptible to fall are predominantly housing buildings. The secondary hazards follow a slightly different distribution with a concentration of risks in the West. 相似文献
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大直径单桩基础是海上风电应用广泛的一种基础形式,严格控制桩基泥面处的位移是保证基础稳定和风机安全运营的关键因素.通过数值方法建立了单桩—海床的三维模型,将可以描述海洋砂土超固结性和结构性的弹塑性本构模型通过UMAT子程序嵌入有限元软件ABAQUS中,桩基承受的波浪荷载通过Morison方程进行计算模拟.针对无波浪荷载、仅作用于海床的波浪荷载、同时作用于桩基和海床的波浪荷载三种情况,分析了海床土的动力响应以及桩基的水平位移之间的差异,探讨了海床土体参数对桩基水平变形的影响.研究结果表明海床土体液化会导致桩基水平变形增加,海床土渗透性、超固结性、结构性对桩基水平位移影响显著,研究成果可为海上风电单桩基础的设计与运维提供参考. 相似文献
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