ارزیابی خطر پذیری لرزه ای و آسیب پذیری سازه ای و جمعیتی، مطالعه موردی: شهر حاجی آباد، استان هرمزگان (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
رخداد زلزله در کشور باعث تخریب شهرها و روستاهای زیادی شده است. وقوع زمین لرزه های شدید در منطقه مورد مطالعه (دو زمین لرزه به بزرگی 6.4 و 6.3 ریشتری در تاریخ 23 آبان 1400 در نزدیکی شهر فین استان هرمزگان) و وجود گسل های فعال (اصلی زاگرس و تراستی زاگرس) در مجاورت شهر حاجی آباد می توانند باعث تخریب سازه ها و تلفات جمعیتی در این شهر شوند. بنابراین، هدف از انجام این تحقیق ارزیابی خطرپذیری لرزه ای، آسیب پذیری سازه ای و جمعیتی شهر در اثر وقوع زمین لرزه احتمالی است تا نواحی آسیب پذیر در برابر خطرات زمین لرزه مشخص شوند. به منظور اجرای این تحقیق داده های زمین شناسی، توپوگرافی و آب شناسی و داده های جمعیتی از سازمان های مرتبط در محدوده شهر حاجی آباد جمع آوری و بر اساس مطالعات میدانی تعداد سازه ها و نوع سازه در هر محله برداشت شد. سپس نقشه پراکندگی سازه ها و نوع آن ها ترسیم شد. در مرحله بعد این داده ها در سامانه GIS آماده سازی و با استفاده از روش های تصمیم گیری چند معیاره مانند روش فرآیند تحلیلی شبکه ای (ANP) و روش منطق فازی (Fuzzy Logic) اولویت بندی و وزن دهی شدند. زیر معیارهای زمین شناسی شامل: فاصله از گسل، ضخامت آبرفت و جنس خاک و رسوبات؛ آب شناسی شامل: عمق آب های زیرزمینی و توپوگرافی شامل: شیب و بی نظمی توپوگرافی هستند. پس از وزن دهی این معیارها و زیر معیارهای هر یک با استفاده از روش ترکیب وزنی خطی (WLC) تلفیق شده، نقشه خطرپذیری زمین لرزه سناریو با بزرگی 7.1 ریشتر در شهر تولید شد. نتایج نشان می دهد 3.68 کیلومتر مربع از وسعت شهر در محدوده خطرپذیری خیلی زیاد قرار دارد. سپس با استفاده از روش های ارزیابی آسیب پذیری سازه ای و منحنی های شکنندگی توسعه یافته در ایران میزان تخریب سازه ها در شهر مورد ارزیابی قرارگرفت که مشخص شد در اثر وقوع زلزله ای به بزرگی 7.1 ریشتر، حدود 80 درصد ساختمان های موجود در شهر دچار تخریب بالای 70 درصد شده و حدود 11000 نفر از جمعیت شهر نیز دچار جراحت شدید یا کشته خواهند شد. نتایج این تحقیق می تواند کارشناسان و برنامه ریزان شهری را در حوزه مدیریت شهری و مدیریت بحران برای اجرای سیاست های کلان کاهش خطر زمین لرزه، ارتقا آمادگی در برابر وقوع زمین لرزه و اولویت بندی مقاوم سازی سازه ها در این شهر یاری رساند.Evaluation of seismic risk and structural and population vulnerability a case study of Haji Abad city - Hormozgan Province
Introduction Earthquake is one of the natural disasters that occurs suddenly and directly affects human life and urban and rural environment. Among the earthquake damages, we can mention human casualties, destruction of buildings and bridges, accumulation of building debris in the boundaries of roads and streets, destruction of electric poles, disruption of movement in the transportation system (Rikalovic, 2014). In order to determine the level of earthquake risk in a region, conducting seismicity studies has a high priority. Also, in order to identify vulnerable places in a city in order to make major decisions in the field of building improvement and retrofitting, it is necessary to carry out structural and demographic seismic vulnerability research (Ansal et al., 2009; Coburn & Spence, 2002). The occurrence of severe earthquakes in the region (two earthquakes with a magnitude of 6.4 and 6.3 on the Richter scale on November 14, 2021 near the city of Fin, Hormozgan province) and the presence of active faults such as Main Zagros and Zagros Trust in the vicinity of Haji Abad city showed the region is exposed to the vey high risk of an earthquake occurnece that can cause the destruction of buildings and population losses in this city. Therefore, the purpose of this research is to assess the seismic risk, buildings and population vulnerability of the city due to a probable earthquake in order to determine the vulnerable areas against earthquake hazard. Materials & Methods In order to carry out this research, geological, topographical and hydrological data and demographic data were collected from related organizations in Hajiabad city. Based on field studies, the number of buildings and the type of structures in each neighborhood were collected, and a map of the distribution of buildins and their types was depicted. Then, these data were prepared in the GIS system and prioritized and weighted using multi-criteria decision-making methods such as Analytical Network Process (ANP) and Fuzzy Logic. The sub-geological criteria include: distance from the fault, thickness of alluvium and the type of soil and sediments, hydrology includes: depth of underground water and topography includes: slope and irregularity of topography. After weighting these criteria and sub-criteria of each, they were ombined using weighted linear combination (WLC) method, and an earthquake hazard map considering an earthquake scenario with a magnitude of 1.7 on the Richter scale was produced in the city. Later, the degree of buildings vulnerability based on the fragility curves that were developed based on past research in Iran were estimated in the classes of without destruction to completely collopsed, and the vulnerability of the population was calculated based on the statistics of the Bam earthquake in the classes of the number of healthy people, injured, injured and hospitalized, and dead people. Results & Discussion The results of seismic microzonation map showed that 3.68 square kilometers of the city is in a very high risk area. Then, based on building vulnerability assessment methods and fragility curves, the destruction level of buildings in the city was evaluated, and it was found that due to an earthquake with a magnitude of 7.1 on the Richter scale, about 80% of the buildings in the city were destroyed over 70% destruction level, and about 11,000 people from the city's population were seriously injured or killed as a result of this earthqauke occurence. Conclusion According to the results of this research, we found that the city of Hajiabad is surrounded by two main faults inclusing Main Zagros and the Trust Zagros faults, which has made it impossible to imagine any safe area in the city. On the other hand, the increase in population and urbanization has caused the extensive development of the city. Therefore, we need efficient disaster and urban management from the relevant organizations to prevent damage and overcome these crises. These measures inculdes rehabilitating worn-out buildings with low-quality materials, preventing construction in the high-risk areas of the city, making suitable plans to increase the resistancy against earthquakes in the city. Moreover, in order to increase security and speed up relief and response operations, in the areas where the risk is very high, according to the regulations, medical and fire stations should be built. In the vulnerable areas of the city where the population density is high, parks and open spaces should be built for temporary and safe accommodation after the earthquake. Therefore, the results of this research can help experts and urban planners in the field of urban management and crisis management to implement macro policies to reduce the risk of earthquakes, improve preparedness against earthquakes, and prioritize the retrofitting of buildings in this city.
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