Lif katkılı kumun hidrolik ve mekanik özelliklerinin belirlenmesi ve yeraltı suyu sızma erozyonuna karşı uygulanmasının incelenmesi
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Date
2018
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Open Access Color
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Abstract
Yeraltı suyu akımı doğal şevlerde erozyona yol açan başlıca sebeplerden biridir. Toprak kaymalarına, şev stabilite (duraylılık) kayıplarına yol açabilir. Stabilite kayıpları ya şev stabilitesini koruyan kuvvetleri artırarak, ya da şevi devirmeye çalışan kuvvetleri azaltarak önlenebilir. Bu çalışmada, şevi koruyan kuvvetleri artırma prensibine dayalı kumlu şev zemine sentetik fiber (lif) katkısı uygulanmaktadır. Burada kullanılan lifin uzunlukları 6 mm ve 18 mm olarak seçilmiştir. Bu kapsamda öncelikle kullanılan kumun zemin sınıflandırma deneyleri gerçekleştirilmiştir (elek analizi, 200 no'lu elekten geçen madde miktarı, minimum ve maksimum boşluk oranı ve özgül ağırlık). Lif katkılı kumun hidrolik özelliklerinin belirlenmesi kapsamında ise hidrolik geçirgenlik ve su tutma kapasitesi deneyleri hem katkısız hem de lif katkılı olmak üzere ağırlıkça polipropilen (PP) lif oranı %0.1, %0.2, %0.3, %0.4, %0.5, %0.6, %0.7, %0.8, %0.9 ve %1.0 olan numuneler üzerinde gerçekleştirilmiştir. Kayma mukavemeti parametrelerinin belirlenmesinde üç eksenli basınç deney düzeneği kullanılmış, konsolidasyonlu drenajlı (CD) deneyler hidrolik testlerde olduğu gibi 10 farklı lif oranında teste tabii tutulmuştur. Bu testlerden elde edilen sonuçlar doğrultusunda üç farklı katkı oranı belirlenmiş (%0.3, %0.5 ve %1.0) ve bu oranlarda üç boyutlu (3D) fiziksel şev modeli deneyleri yapılmıştır. Laboratuvarda 100 cm uzunluğunda, 50 cm genişliğinde ve 55 cm yüksekliğinde 45 derecelik şev elde edilecek şekilde katkısız ve lif katkılı kum 3D erozyon kanalı içerisinde inşa edilmiştir. Üç farklı hidrolik yük sınır koşulu (25, 38 ve 50 cm-su) altında, iki farklı lif uzunluğu (6mm ve 18mm) ve üç farklı katkı oranı (%0.3, %0.5 ve %1.0) kullanılarak toplam 21 adet deney (18 adet katkılı, 3 adet katkısız) yapılmıştır. Şev yüzeyinde meydana gelen şekil değiştirmeler üç boyutlu lazer tarayıcı ile taranmış ve erozyon hacimleri belirlenmiştir. Sızma suyu erozyonunun önlenmesinde zemin içerisindeki lif katkısının etkili olduğu görülmüştür.
Subsurface flow has been one of the major factors which provoke erosion on natural slopes. This could lead to landslides, and the loss of the slope stability. The loss of slope stability could be prevented either by increasing the forces which retain the slope stability or by decreasing the forces which drive the failure of the slope. In this study, the admixture of synthetic fiber into sandy slope was carried out on the basis of increasing the forces which retain the slope. Fiber lengths used in this study were selected as 6 mm and 18 mm. In this respect, the classification tests of the sand used in this study was carried out initially (particle size distribution, analysis of the amount of the particles passing through the mesh no 200, minimum and maximum opening size and specific gravity) In order to determine the hydraulic properties of fiber reinforced sand, hydraulic permeability and water retention tests were performed on both unreinforced and fiber reinforced samples with polypropylene fiber gravimetric content of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1.0%. Triaxial compression test setup was used in determination of shear strength parameters and, consolidated drained (CD) tests were conducted on 10 different fiber content as in the hydraulic tests. In accordance with all the results obtained from these tests, three different gravimetric contents were selected (0.3%, 0.5% and 1.0%) for three-dimensional physical slope experiments. Both unreinforced and fiber-reinforced sand was constructed in 3D laboratory erosion flume to obtain a 45o slope with dimensions of 100 cm long, 50 cm wide and 55 cm high. A total of 21 experiments (18 reinforced and 3 unreinforced slope ) were performed using two different fiber length (6 mm and 18 mm) and three different fiber gravimetric content (0.3%, 0.5% and 1.0%) under 3 different hydraulic head boundary conditions (25-, 38-, and 50 cm-water). The displacements occurred on the slope surface were measured by using three-dimensional laser scanner and the volume of seepage erosion was computed. In an effort to prevent seepage erosion, fibers were found to be an effective additive to the soil.
Subsurface flow has been one of the major factors which provoke erosion on natural slopes. This could lead to landslides, and the loss of the slope stability. The loss of slope stability could be prevented either by increasing the forces which retain the slope stability or by decreasing the forces which drive the failure of the slope. In this study, the admixture of synthetic fiber into sandy slope was carried out on the basis of increasing the forces which retain the slope. Fiber lengths used in this study were selected as 6 mm and 18 mm. In this respect, the classification tests of the sand used in this study was carried out initially (particle size distribution, analysis of the amount of the particles passing through the mesh no 200, minimum and maximum opening size and specific gravity) In order to determine the hydraulic properties of fiber reinforced sand, hydraulic permeability and water retention tests were performed on both unreinforced and fiber reinforced samples with polypropylene fiber gravimetric content of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1.0%. Triaxial compression test setup was used in determination of shear strength parameters and, consolidated drained (CD) tests were conducted on 10 different fiber content as in the hydraulic tests. In accordance with all the results obtained from these tests, three different gravimetric contents were selected (0.3%, 0.5% and 1.0%) for three-dimensional physical slope experiments. Both unreinforced and fiber-reinforced sand was constructed in 3D laboratory erosion flume to obtain a 45o slope with dimensions of 100 cm long, 50 cm wide and 55 cm high. A total of 21 experiments (18 reinforced and 3 unreinforced slope ) were performed using two different fiber length (6 mm and 18 mm) and three different fiber gravimetric content (0.3%, 0.5% and 1.0%) under 3 different hydraulic head boundary conditions (25-, 38-, and 50 cm-water). The displacements occurred on the slope surface were measured by using three-dimensional laser scanner and the volume of seepage erosion was computed. In an effort to prevent seepage erosion, fibers were found to be an effective additive to the soil.
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Keywords
İnşaat Mühendisliği, Civil Engineering