ارزیابی عملکرد روش های فرم و مونت کارلو در محاسبه احتمال خرابی لغزشی سد بتنی وزنی تحت بارهای استاتیکی

نویسندگان
1 دانشجوی دکتری/دانشگاه سیستان و بلوچستان
2 دانشگاه سیستان و بلوچستان
چکیده
بدون شک خرابی یک سد بتنی خسارات مالی و جانی جبران ناپذیری را به یک جامعه وارد خواهد کرد. در این پژوهش با انتخاب سد بتنی وزنی Sariyar واقع در ترکیه، بعنوان مطالعه موردی، احتمال خرابی این سد در مود لغزشی محاسبه شده است. مهم ترین عامل در خرابی لغزشی یک سد، افزایش سطح آب مخزن بوده که با افزایش نیروی جانبی و آپلیفت، احتمال خرابی نیز افزایش خواهد یافت. لذا برای درنظر گرفتن حالات مختلف که ممکن است برای یک سد پیش بیاید، تمامی ارتفاع های محتمل برای دریاچه این سد شبیه سازی شده و احتمال خرابی و شاخص قابلیت اطمینان در این حالات با استفاده از دو روش مونت کارلو و فرم بدست آمد و با یکدیگر مقایسه شده است. همچنین تاثیر تعداد نمونه های تولید شده بر پاسخ های بدست آمده در روش مونت کارلو نیز مورد بحث قرار گرفته است. نتایج نشان دادند روش مونت کارلو در برخی حالات که مقاومت سیستم بسیار بیشتر از بار موجود می باشد و تابع شرایط حدی فاصله زیادی با اجتماع نمونه ها دارد، ممکن است با هر تعداد نمونه قادر به ارائه احتمال خرابی نباشد. در این حالات می توان با استفاده از روش فرم، مقادیری برای شاخص قابلیت اطمینان محاسبه نمود، اما مشخص شد که این مقادیر فاصله زیادی با واقعیت خواهند داشت. با افزایش نیروهای وارده، پاسخ های بدست آمده از روش مونت کارلو از دقت بالایی برخوردار خواهند بود ولی روش فرم، میزان احتمال خرابی را کمتر از آنچه که هست نشان خواهد داد.

کلیدواژه‌ها


عنوان مقاله English

Performance Evaluation of Monte Carlo Simulation and FORM Method to Calculate Probability of Failure for Concrete Gravity Dams in Sliding Failure Mode under Static Loading

نویسندگان English

Farid MiarNaeimi 1
Golamreza Azizyan 2
Gholamhossein Akbari 2
1 PhD Student/University of Sistan and Baluchestan
2 University of Sistan and Baluschestan
چکیده English

Failure of a concrete gravity dam will cause unavoidable human loss and financial damages. In this study SARIYAR concrete gravity dam, located in turkey was chosen as a case study and its probability of sliding failure in various condition was studied. The most important reason in sliding failure of a concrete dam was lateral and uplift loads, caused by increase in the level of reservoir water. Different scenarios were considered in which might happen for a dam, all the possible height of reservoir water simulated. Afterward, Probability of failure and reliability index was calculated with Monte Carlo simulation and FORM method in all conditions and comparison with each other. The influence of the Number of Simulations (NOS) in the Monte Carlo method was also discussed. Results showed that, in some cases, the resistance of the system was much more than the loads and limit state function had a significant distance from samples. In such states, Monte Carlo was unable to calculate the probability of failure with each NOS but FORM method obtained the Reliability Index (β) in these situations. It became clear that these values were far from reality. With increase in the forces, responses from Monte Carlo had a high degree of precision. The probability of failure generated by FORM method was less than a reality. Failure of a concrete gravity dam will cause unavoidable human loss and financial damages. In this study SARIYAR concrete gravity dam, located in turkey was chosen as a case study and its probability of sliding failure in various condition was studied. The most important reason in sliding failure of a concrete dam was lateral and uplift loads, caused by increase in the level of reservoir water. Different scenarios were considered in which might happen for a dam, all the possible height of reservoir water simulated. Afterward, Probability of failure and reliability index was calculated with Monte Carlo simulation and FORM method in all conditions and comparison with each other. The influence of the Number of Simulations (NOS) in the Monte Carlo method was also discussed. Results showed that, in some cases, the resistance of the system was much more than the loads and limit state function had a significant distance from samples. In such states, Monte Carlo was unable to calculate the probability of failure with each NOS but FORM method obtained the Reliability Index (β) in these situations. It became clear that these values were far from reality. With increase in the forces, responses from Monte Carlo had a high degree of precision. The probability of failure generated by FORM method was less than a reality. Failure of a concrete gravity dam will cause unavoidable human loss and financial damages. In this study SARIYAR concrete gravity dam, located in turkey was chosen as a case study and its probability of sliding failure in various condition was studied. The most important reason in sliding failure of a concrete dam was lateral and uplift loads, caused by increase in the level of reservoir water.

کلیدواژه‌ها English

Concrete dam
Sliding Failure
Monte Carlo
Form
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