بررسی طبقه‌بندی نوع خاک با استفاده از منطق فازی بر اساس استاندارد 2800

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده مهندسی عمران و مرکز تحقیقات زلزله دانشگاه صنعتی سهند، تبریز، ایران

چکیده

طبقه‌‌‌بندی نوع زمین ساختگاه به منظور طراحی ساختمان‌ها در برابر زلزله تابعی از وضعیت لایه‌های خاکی و سنگی زمین منطقه است که مطابق آیین‌نامه‌های معتبر مربوطه، خود تابعی از پارامترهای مکانیکی و دینامیکی خاک می‌باشد. به طوری که این پارامترها بر اساس متوسط سرعت موج برشی، متوسط عدد نفوذ استاندارد و متوسط مقاومت برشی زهکشی نشده در خاک‌های چسبنده در لایه‌‌‌های مختلف خاک تا عمق 30 متری از تراز پایه تعیین می‌گردند. با توجه به عدم قطعیت‌های موجود در پارامتر‌‌های مذکور و نیز در نظر گرفتن این مسئله که مقادیر این پارامتر‌‌ها در توده‌‌‌ی واقعی با مقادیر حاصل از آزمایش‌های آزمایشگاهی به دلیل خطاهای موجود متفاوت است، لذا تعیین دقیق پارامتر‌‌های مذکور مستلزم به کارگیری روش‌های آماری و احتمالاتی می‌‌‌باشد. با توجه به پیچیدگی‌های محاسباتی روش‌های آماری و احتمالاتی، در این تحقیق از سیستم استنتاج فازی جهت تصمیم‌‌گیری در انتخاب نوع زمین، استفاده گردیده است که قادر به در نظرگیری عدم قطعیت‌ها بدون نیاز به محاسبات پیچیده‌‌‌ی ریاضی می‌‌‌باشد. بدین منظور، پس از تعیین پارامتر‌های موثر در تعیین نوع خاک، توابع عضویت مثلثی برای آن‌ها انتخاب و در نهایت سیستم استنتاج فازی طراحی می‌شود. با توجه به نتایج، ملاحظه می‌شود که مدل پیشنهادی در مرز‌های بین دو نوع طبقه متوالی خاک، پاسخ دقیق‌‌تری نسبت به استاندارد ارائه می‌‌دهد. همچنین زمانی که مقادیر پارامترهای موثر در انتخاب نوع زمین به دور از مرزهای بین طبقات متوالی خاک قرار می‌گیرند، سیستم استنتاج فازی و استاندارد 2800 جواب‌های یکسانی ارائه می‌دهند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Fuzzy classification of soils based on Iranian standard of 2800

نویسندگان [English]

  • Haleh Meshginghalam
  • Mehrdad EMAMI Tabrizi
  • Mohammad Reza Chenaghlou
Ph.D. Candidate, Civil Engineering Faculty, Sahand University of Technology (SUT), Tabriz
چکیده [English]

Soil classification is a function of a region’s geological conditions, which according to the Iranian earthquake standard of 2800, it is consequently a function of average shear wave velocity, as well as average SPT blow count, and average undrained shear strength of cohesive soils in different layers for up to 30 meters depth. Boundaries of these geotechnical parameters are often defined as different crisp values in the earthquake design codes. Because of the uncertainties in the mentioned parameters and also the difference between values of these parameters in the real material and values obtained from the experimental tests for the determination of these parameters, statistical and probabilistic methods is needed. Due to the computational complexity of statistical and probabilistic methods, in this research, a fuzzy inference system has been used for the decision of the classification of soil type, which can consider uncertainties without the need for complex mathematical calculations. For this purpose, after defining the effective parameters for determining the soil type, triangular membership functions were selected for them, and finally, a fuzzy inference system was designed. According to the results, the proposed model provides more accuracy than the standard in the boundaries between two successive soil classes. Also, when the values of the parameters are far from the boundaries between successive soil classes, the fuzzy inference system and the standard provide the same answers.

کلیدواژه‌ها [English]

  • Soil classification
  • Iranian Standard of 2800
  • Uncertainty
  • Statistical and Probabilistic methods
  • Fuzzy Inference System
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