Termal Şok Etkisinin Kaya Malzemelerinin Dayanım Kaybı Özellikleri üzerindeki Etkileri: Termal Yorulma üzerine Deneysel bir Çalışma

Öz

Doğu Karadeniz bölgesinden dört farklı kaya malzemesinin, 300 ^oC’ye kadar değişen sıcaklık değişimlerine sahip termal döngüler altında porozite değerlerindeki değişim, çatlama, parçalanma ve dayanım kaybı özellikleri incelenmiştir. Numunelerin soğuma süreleri ve soğuma esnasındaki birim deformasyonları da bu çalışma kapsamında belirlenmiştir. Toplamda altmış adet karot numunesi test edilmiştir. Elde edilen sonuçlara göre, döngü sayısı arttıkça porozite değerlerinde artış, dayanım değerlerinde düşüş yaşanmakta olduğu, kaya malzemesi türüne bağlı olarak çatlamalar ve parça kopmaları şeklinde bozunmaların olabildiği görülmüştür. Çalışmadaki termal döngülerde ani sıcaklık değişimleri incelenmiştir. Örneğin, beşinci ve son döngüde numuneler 250 ^oC etüvden alınarak doğrudan -50 ^oC sıcaklıktaki soğutma kabinine alınmıştır. Isıtma işleminden sonra numuneler suda ve havada farklı ortamlarda soğutulmuşlardır. Bu çalışma, kaya malzemelerinin termal yorulma karşısındaki dirençlerinin değerlendirilmesi üzerine ısıtma-soğutma işlemleri prosedürün belirlenmesi ve geliştirilecek yeni bir metoda yönelik çalışmalara kullanışlı bir referans oluşturmayı amaçlamıştır.

Anahtar Kelimeler

• Dayanım Kaybı,Kaya Dayanımı,Termal Döngü,Termal Yorulma

Thermal Shock Effect on Strength Loss Properties of Rock Materials: An Experimental Study on Thermal Fatigue Durability

Öz

Four different types of rock materials from Eastern Black Sea Region of Turkey were investigated to determine their change in porosity as well as the degree of cracking, fracturing, disintegration and strength loss under heating-cooling cycles with variations in temperatures up to 300 C^o. Cooling time and thermal strains of the rock specimens were also determined in this study. Totally, sixty rock core samples were tested to evaluate their physico-mechanical and mechanical properties. Thermal cycling was found to lead for increase in the porosity of the rocks, making new cracks, particle disintegration for two types of tested rocks and considerable losses in uniaxial compressive strength values of all the rock materials tested in this study. The purpose of this study is to investigate immediate changes in temperature values rather than step by step heating up to a target temperature. For instance, rock samples were directly put in 250 ^oC stove from a -50 ^oC cabin in the last and fifth thermal cycling. After the heating process, specimens were cooled in water and air. This study aims to be a usable reference to establish a thermal change procedure and improve a new testing method for determination of thermal fatigue durability of rock materials.

Anahtar Kelimeler

• Strength Loss,Rock Strength,Thermal Treatment,Thermal Fatigue

Kaynakça

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