با ارزیابی و پایش کمی و کیفی برنامههای مدیریت خطرپذیری و مدیریت بحران در گسترش حمل و نقل ریلی کلان شهر تهران و به تبع آن با بررسی میزان مخاطرات و آسیبپذیری شبکه ریلی کشور، خلأ ناشی از مدیریت هوشمند شهری در ابعاد برنامهریزی کالبدی و فضایی کاملاً مشهود است. نکته بارز در مواجهه با بحرانهایی همچون زمینلرزه و سیل در خطوط حمل و نقل زیرزمینی (مترو) عمدتاً وابسته به فرضیات آزمون و خطا ، پیروی از روشهای مدیریت سنتی و ضعف در آیندهنگری و آیندهپژوهی است. در گسترش خطوط ریلی زیرزمینی، بررسی مطالعات زمینساختی (تکتونیکی)، پهنههای لرزهخیز، تفاوت جنس زمین و مسیر گسلهای شمال و جنوب تهران (پیش از بحران) و توجه به آسیب پذیری ایستگاه مترو و احتمال تشدید بحران با تخریب بافت فرسوده شهری، هنگام وقوع زلزله و سیل بسیار حائز اهمیت است. این مقاله، با تمرکز بر موضوع ارزیابی خطرپذیری و آسیبپذیری گسترش شبکه حمل و نقل ریلی و با رویکرد پایش مخاطرات کالبدی و فضایی ایستگاههای مترو انجام شده است. روش انجام کار ارزیابی خطرپذیری از طریق تنظیم فهرست سنجشی پژوهشگر ارائه شده است. بدین منظور سه ایستگاه نواب، تجریش و دروازه شمیران به عنوان ایستگاه های منتخب شبکه متروی تهران مورد مطالعه قرار گرفت. در انجام پژوهش، از روشی ترکیبی و مبتنی بر مطالعات کتابخانهای، بررسی سوابق و مدارک، تکنیک دلفی، روش تحلیل سلسله مراتبی و رویهمگذاری لایهها استفاده شده است. نتایج ارزیابی آسیبپذیری نشانگر آن بوده است که تمامی ایستگاه ها در محدوده آستانه خطر قرار دارند و نیازمند اتخاذ تدابیری هوشمند در تمامی مراحل قبل، حین و بعد از بحران زمینلرزه و به کارگرفتن راهکارهای مدیریتی و اجرایی به منظور کاهش آسیبهای احتمالی میباشد.
عنوان مقاله [English]
Risk Assessment of Tehran Subway Stations During Earthquakes with an Approach to Reduce Physical Vulnerability Through Intelligent Urban Management(Case study: Tajrish, Darvazeh Shemiran, and Navab Subway Stations)
Lack of by intelligent management in physical and spatial planning is evident in the evaluation and monitoring of the quantity and the quality of disaster and risk management plans in rail transportation development of Tehran Metropolitan and, consequently, in examining the risks and vulnerability of the rail network in the country. Obviously, the crises such as earthquakes and floods on subway lines are largely dependent on trial and error hypotheses, traditional management practices, and poor future studies.
Regarding the tectonic studies, it seems that some factors such as seismic zones, differences in the soil types, changes in the north and south fault lines (before the disaster) of Tehran, the vulnerability of the subway stations, and the possibility of crisis exacerbation with the destruction of deteriorated urban fabrics during earthquake and flood are of vital importance in the development of underground railways. Focusing on earthquake vulnerability assessment and the role of intelligent risk management in the development of railway transportation network with an approach to monitor the physical and spatial hazards of subway stations, this research tries to access the information about fault lines, watercourses and subway stations of Tehran for intelligent monitoring of the crises, and identification of the nearest medical centers and urban open spaces regarding the type of crisis.
Therefore, three subway stations in Tehran (Tajrish, Darvazeh Shemiran, and Navab Subway Stations) were selected to be studied because of their locations in busy and important areas of Tehran, high level of passenger traffic, high land use density of the surrounding area, being located in three separate different areas, proximity to hazardous functions, year of construction, the station depth, proximity to main and secondary fault areas, and the distance from the watercourses.
In the research, a combination of research methods is used based on library studies, review of records and documents, Delphi technique2, hierarchical decision making method and layer overlap. First, the existing maps and field observations were scrutinized thoroughly in order to investigate and analyze the information. Next, the criteria for assessing the risks at Tehran subway stations were achieved based on experts’ opinion. Then appropriate maps for subway stations in the studied areas were proposed according to specific factors (fault, watercourse, deteriorated fabric, distance from the medical stations, …). These maps indicate the appropriateness of the stations in relation to the location and the function of the current stations. Regarding the various effects of different layers on the evaluation process, the weighted coefficient of each layer was calculated by analytical Hierarchy process (AHP). The number of layers in each category in terms of importance and the effect of each category on the evaluation process were also calculated respectively from the least to the most important as follows: The distance from the fault, the station depth, the distance from fire stations, the distance from the channel (weight 4); the number of regular stairs, the area of nearby open spaces, the number of entrance and exit gates, the exit width, the number of emergency exits, the distance from medical centers, abundance of firefighting equipment, emergency ventilation, the density of the surrounding fabric, proximity to BRT lines, the existence of helicopter landing site, lack of upstream water resources, the number of passengers per day, proximity to high-rise structures, the age of the surrounding structures, the area of the deteriorated urban fabric, the bridge spans (weight 3); the number of escalators, the number of elevators, land slope at the station (slope stability), the existence of a realm for power supply facilities, the distance from fuel stations, the distance from adjacent stations, the desirability of passage network around the stations (fabric density), the existence of fine grains in the surrounding area (weight 2); the existence of proper access, the distance to police station, proximity to hazardous functions, intersection with underground tunnels, the presence of peripheral organic passages, the skyline of the surrounding functions(weight 1).
The results of the risk assessment indicate that all stations are within the danger threshold and adopting smart management and executive solutions to reduce possible damage is essential. Based on the average score obtained from the analysis of the stations studied and their relevance to the risk index table, it is clear that all three stations are within the "risk threshold", which highlights the need for careful scrutiny of the issues increasing the risks art the stations. Based on the scores assigned to each of the studied stations, it was revealed that the "distance from the fault" and the "number of emergency exits" at Tajrish station had the lowest score (highest risk). In addition, at Darvazeh Shemiran and Navab stations, " the number of lifts" and "number of emergency exits" had the lowest score.
Still after years of extensive research on the key role of risk management in mitigating natural disasters (earthquakes and floods), the development of underground transportation network (subway) is less likely to follow methods of intelligent risk management, especially in cities such as Tehran where the deteriorated fabrics are at high risk due to the soil type, and the location of faults. In examining the risk level of a subway station in an earthquake crisis, the distance from the fault, the depth of the station and the existence of a tunnel, each play a decisive role for intelligent management of the crisis. Also, the overlapping of other related data, reveals the dimensions, extent and severity of the crisis. Accordingly, in order to eliminate or reduce the effects of risk factors in the development of the underground transportation network, all the tectonic and seismic engineering considerations, including the material of the layers, proximity to the faults, land slopes, and groundwater should be considered from the early stage of feasibility studies, to the final stages of determining the route and location of subway stations. Since some subway stations are located in the vicinity of deteriorated fabrics or high-rise structures, the earthquake crisis might exacerbate with the collapse of the buildings and the obstruction of the surrounding routes. The dependence of subway facilities on city infrastructure is considered a weakness. Electrical, water, telephone and other facilities are completely dependent on ground installations, and if they are damaged in any situation (normal and critical), the entire subway network facilities will be disrupted; therefore, it is necessary to devise emergency and intelligent systems.