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Analysis the Effect of soil permeability on stability of the upstream shell of the dam under rapid drawdown(Braddon dam)

تحليل تأثير نفاذية التربة المكونة لوجه السد الأمامي على استقراره في ظروف التفريغ السريع لبحيرته (حالة سد برادون)

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 Publication date 2015
and research's language is العربية
 Created by Shamra Editor




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The stability of the upstream shell of the dams is changed under the rapid drawdown condition where the pore water pressure has a different values according to the soil permeability. This paper considers the stability of the upstream shell of the "Braddon" dam with many types of soil and analyses each type under two rapid drawdown programs, the first program is when the discharge happens, according to the irrigation outlet by 25 m3/s, and the second program is when the discharge happens according to the tunnel conversion of the river by 500 m3/s. The obtained results show, that the stability of the upper slope under considered boundary conditions changed according to the soil type. Some soil have good stability factor while other soil collapsed .Accordingly, we can conclude that the type of soil of the upper dam slope is important and we could chose the appropriate type which does not cause dangerous during the rapid drawdown. Also the study shows that: the highest values of the safety factors result when the slopes are formed of high permeability soils as well as the slopes of homogeneous soil, while the soils formed of materials between them appeared decreasing values of safety factors.


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Research summary
يتناول البحث تحليل تأثير نفاذية التربة المكونة للوجه الأمامي لسد برادون على استقراره في ظروف التغريغ السريع. يتم ذلك من خلال دراسة أنواع مختلفة من الترب وتحليل استقرار كل نوع تحت تأثير برنامجي تغريغ مختلفين: الأول يعتمد على غزارة مأخذ الري البالغة 25m²/s، والثاني يعتمد على غزارة نفق تحويل المجرى النهري البالغة 500m²/s. أظهرت النتائج أن استقرار المنحدر الأمامي يتأثر بشكل كبير بنوع التربة، حيث أن بعض الترب توفر عامل استقرار مقبول بينما تسبب ترب أخرى انهياراً للمنحدر. يوضح البحث أن الترب ذات النفاذية العالية والترب المتجانسة مع تربة النواة توفر عوامل أمان أعلى، بينما الترب ذات النفاذية المتوسطة تظهر انخفاضاً في قيم عامل الاستقرار. يوصي البحث بضرورة اختيار التربة المناسبة أثناء مرحلة الدراسة لتجنب المخاطر المحتملة في ظروف التغريغ السريع.
Critical review
دراسة نقدية: يعتبر البحث مهماً في مجال هندسة السدود، حيث يقدم تحليلاً شاملاً لتأثير نفاذية التربة على استقرار السدود في ظروف التغريغ السريع. ومع ذلك، يمكن توجيه بعض الملاحظات النقدية لتحسين البحث. أولاً، يمكن أن يكون من المفيد تضمين دراسات ميدانية إضافية لدعم النتائج المستخلصة من النماذج الحاسوبية. ثانياً، يمكن توسيع نطاق الدراسة ليشمل تأثير عوامل أخرى مثل التغيرات المناخية والزلازل على استقرار السدود. ثالثاً، يمكن تحسين العرض البياني للنتائج لتكون أكثر وضوحاً وسهولة في الفهم. وأخيراً، يمكن أن يكون من المفيد تقديم توصيات عملية أكثر تفصيلاً لمهندسي السدود بناءً على النتائج المستخلصة.
Questions related to the research
  1. ما هو الهدف الرئيسي من البحث؟

    الهدف الرئيسي من البحث هو تحليل تأثير نفاذية التربة المكونة للوجه الأمامي لسد برادون على استقراره في ظروف التغريغ السريع وتحديد أنواع الترب التي توفر عامل استقرار مقبول وتلك التي تسبب انهياراً للمنحدر الأمامي.

  2. ما هي الأدوات والبرامج المستخدمة في البحث لتحليل استقرار السد؟

    تم استخدام برنامج GEO-STUDIO، وخاصةً أدوات SEEP/W وSLOPE/W لتحليل التسرب والاستقرار في النماذج المعقدة والبسيطة وفقاً لنظرية العناصر المنتهية.

  3. ما هي النتائج الرئيسية التي توصل إليها البحث؟

    النتائج الرئيسية تشير إلى أن الترب ذات النفاذية العالية والترب المتجانسة مع تربة النواة توفر عوامل أمان أعلى، بينما الترب ذات النفاذية المتوسطة تظهر انخفاضاً في قيم عامل الاستقرار. كما تبين أن عوامل الأمان تقل بشكل أكبر في برنامج التغريغ الثاني مقارنة بالأول.

  4. ما هي التوصيات التي يقدمها البحث لمهندسي السدود؟

    يوصي البحث بضرورة اختيار التربة المناسبة أثناء مرحلة الدراسة لتجنب المخاطر المحتملة في ظروف التغريغ السريع، ودراسة تأثير عوامل أخرى مثل معدلات تغريغ متغيرة مع الزمن وتباين خواص نفاذية التربة المكونة للمنحدر الأمامي.


References used
ALONSO,E;PINYOL,N,Slope stability under rapid drawdown conditions, UniversitatPolitècnica de Catalunya, Barcelona,Canada2003,367
FREDLUND,M.Combined Seepage and Slope Stability Analysis of RapidDrawdown Scenarios for Levee Design.Geo-Frontiers2011© ASCE ,2011,1595- 1604
TRAN,T.stability problems of an earthfill dam in rapid drawdown condition.SlovakRepublicGrant Project No. 1/9066/02, 2004
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