STABILITY ANALYSIS OF AN EMBANKMENT DAM DURING RAPID DRAWDOWN OF WATER IN RESERVOIR

Öz

This paper focuses on stability analysis carried out on fictional embankment dam with clay core on impervious bed and calculating results using SLIDE V.6.0 and PLAXIS softwares. The stability of embankment slopes was checked by five different analysis methods: Fellenuis, Bishop, Janbu, Morgenstern-Price and Spencer methods respectively. It is assumed that rapid drawdown rate 3m/day and reservoir water level falling down to 3 m within 8 days. The stability of the upstream slope of the dam decreased dramatically but still in stable during drawdown condition. The factor of safety was greater than 1.3 for all reservoir condition. It was concluded that the factor of safety against sliding of the dam slopes decreases slightly within the short period after the start of rapid drawdown of water in the reservoir, then starts to increase. This is caused by dissipation of excess pore water pressure with time which leads to increase the effective stresses in the soil and hence increase its shear strength.

Anahtar Kelimeler

• Slide
• Embankment Dam
• Rapid Drawdown
• Stability.

BİR DOLGU BARAJIN REZERVUARINDAKİ SUYUN ANİ ÇEKİLMESİ SIRASINDAKİ STABİLİTE ANALİZİ

Öz

Bu çalışma, geçirimsiz yatak üzerinde kil çekirdekli kurgusal dolgu barajının stabilite analizine ve SLIDE V.6.0 ve PLAXIS yazılımları kullanılarak sonuçların hesaplanmasına odaklanmaktadır. Dolgu şevlerinin stabilitesi beş farklı analiz yöntemi ile kontrol edilmiştir: sırasıyla Fellenuis, Bishop, Janbu, Morgenstern-Price ve Spencer yöntemleri. Suyun ani çekilme hızının 3m/gün olduğu ve rezervuar su seviyesinin 8 günde 3 m'ye düştüğü varsayılmaktadır. Gözlem sonuçlarına göre barajın memba eğiminin stabilitesi önemli ölçüde azalmıştır, ancak suyun çekilmesi durumunda hala stabildir. Rezervuar su seviyesinin tüm durumları için güvenlik faktörü 1.3'ten büyüktür. Rezervuarda ani su çekilmesinin başlamasından sonra kısa sürede baraj yamaçlarının kaymasına karşı güvenlik faktörünün bir miktar azaldığı, ardından artmaya başladığı sonucuna varılmıştır. Bu, zemindeki efektif gerilmelerin artmasına ve dolayısıyla kayma mukavemetinin artmasına yol açan aşırı boşluk suyu basıncının zamanla azalmasından kaynaklanmaktadır.

Anahtar Kelimeler

• Şev
• Dolgu baraj
• Ani su çekilmesi
• Stabilite

Kaynakça

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