Baraj Rezervuarlarında Heyelanlardan Kaynaklanacak İtki Dalga Özelliklerinin Ampirik İlişkilerle Değerlendirilmesi: Borçka Barajı Örneği

Abstract

Bu çalışmada Borçka Baraj Rezervuarında baraj gövdesine 4 km uzaklıkta bulunan paleo-heyelan malzemesinin aktif hale gelmesi durumunda oluşacak itki dalgalarının çevresel etkilerinin ampirik ilişkiler kullanılarak belirlenmesi amaçlanmıştır. Çalışmada, heyelan malzemesine ait farklı kalınlık ve genişlik değerleri dikkate alınarak, 0.5 ile 1 milyon metreküp arasında değişen hacimlerde malzemenin rezervuara akması durumu için 3 farklı senaryo geliştirilmiştir. Heyelan kaynaklı dalganın rezervuarda her yöne dairesel olarak yayılacağı belirlenmiş, dalga özellikleri 3 boyutlu ampirik yaklaşımlarla değerlendirilmiştir. Farklı senaryolar için, dalga hızının 27.1 ile 27.7 m/s arasında değişeceği, en yüksek hız değeri için karşı kıyıya ulaşacak dalga yüksekliğinin 23 metre olacağı ve bu dalganın karşı kıyıda yamaç boyunca 42.3 metre yükseleceği hesaplanmıştır. En düşük dalga hızı değeri için ise dalga yüksekliği 18.5 m ve yamaç boyunca ilerleme yüksekliği ise 32.5 metre olacaktır. Baraja ait 4 metrelik dalga payı değeri dikkate alındığında, rezervuar boyunca ilerleyerek baraj gövdesine ulaşacak dalganın gövde için bir tehlike oluşturmayacağı belirlenmiştir. Basit rezervuar geometrileri ve kısa mesafeler için heyelan kaynaklı dalga özelliklerinin hesaplanmasında ampirik eşitliklerin kullanılması önerilirken, kompleks rezervuar geometrileri için mutlaka 3 boyutlu sayısal modellerin kullanılması, bu modellerde ise sayısal tabanlı yamaç duraylılık analizleri uygulanarak hesaplanacak heyelan hacmi değerinin kullanılması gerekliliği göz ardı edilmemelidir.

Keywords

• Heyelan,Rezervuar,Dalga,Borçka Barajı

Assessment of landslide generated impulse waves in dam reservoirs using empirical relations: a case study on Borçka Dam

Abstract

The aim of this study is to investigate environmental effects of impulse waves originated from reactivation of a paleo-landslide located 4 km far from the dam body in Borçka Dam reservoir using empirical relations. Considering different values of landslide width and thickness, 3 different scenarios were defined for the slide of landslide material in volumes ranging from 0.5 to 1 million cubic meters. The wave propagation in the reservoir was defined as radially, and properties of landslide generated impulse waves were evaluated using 3D empirical approaches. For different scenarios, it is determined that the wave height values range between 27.1 and 27.7 m/s, the wave height value for opposite shore reaches 23 m and run-up height value is 42.3 m for highest wave celerity value. The values of wave height and run-up height were calculated as 18.5 m and 32.5 m respectively for lowest wave celerity value. Considering the 4-meter freeboard for the dam, it was determined that the wave propagating through the reservoir and reaching the dam body would not create a danger for the body. Empirical equations can be used for the calculation of landslide-induced wave characteristics for simple reservoir geometries and short distances. But 3D numerical models should be preferred for complex reservoir geometries, and the need to use the landslide volume value to be calculated by applying numerical based slope stability analyzes should not be ignored in these models.

Keywords

• Landslide,Reservoir,Wave,Borçka Dam

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