Dolgu Barajlarda Çekme Çatlaklarının Duvarına Etkiyen Gerilmelerin Fiziksel Olarak Modellenmesi

Yıl 2024, Cilt: 10 Sayı: 2, 285 - 299, 25.06.2024

Sadettin Topçu Hasan Tosun

https://doi.org/10.28979/jarnas.1377362

Öz

Dolgu barajların güvenliği, inşaatında kullanılan malzemelerin su akımıyla taşınması olarak tanımlanan içsel erozyon ile tehdit edilmektedir. Özellikle geçirimsiz perde inşaatında kullanılan kil zeminlerde gelişen çekme çatlaklarında oluşan içsel erozyon türlerinden olan kaçak erozyon, çekme çatlağının derinliği ve genişliği ile ilgili hidrolik parametrelerle kontrol edilir. Ek olarak kil zeminin içsel erozyon direncini kapsayan malzeme özellikleri de göz önünde tutulur. Bu çalışmada bu kontrol faktörlerine ilave olarak çatlama sonrası çatlak duvarlarında gelişen gerilme koşullarının da dikkate alınabilmesi için dolgu barajlardaki çatlak mekanizmasından faydalanılarak yeni bir yaklaşım üretilmiştir. Bu yaklaşımın da laboratuvar koşullarında fiziksel olarak modellenebilmesi için nümerik analiz yardımıyla yeni bir test cihazı; Modifiye Edilmiş Gerilme Kontrollü Üç Eksenli Test Cihazı (MGÜET), tanımlanmıştır. Duvarları tam düşey ve tam yatayda olan çekme çatlaklarının çatlama sonrası duvarlarında toplam gerilme esasında oluşan asal gerilme koşulları, bu test cihazıyla laboratuvar koşullarında oluşturulabilmiştir. Dolgu barajlarda gelişen çekme çatlakları, silindirik zemin örneğinde oluşturulan dairesel bir delik ile modellenmiştir. Böylece, içi boş silindirik cisimlerin mekaniğinden faydalanılarak çekme çatlaklarının çatlama sonrası duvar gerilmeleri, dairesel deliğin duvarında gelişen gerilmeler ile açıklanabilmektedir.

Anahtar Kelimeler

Çatlak, dolgu baraj, içsel erozyon, ansys workbench, üç eksenli gerilme

Physical Modelling of Stresses Affecting the Walls of Tensile Cracks in Embankment Dams

Öz

The safety of embankment dams is threatened by internal erosion, defined as the transporting materials used in their construction by water flow. One of the types of internal erosion, such as Concentrated Leak Erosion that occurs in tension cracks that develop in clay soils used in impervious zone construction, is controlled by hydraulic parameters related to the depth and width of the tension crack. Also, material properties, including the clay soil's internal erosion resistance, are considered. This study produced a new approach by utilizing the crack mechanism in an embankment dam to evaluate the stress conditions developing in the crack walls after cracking. To physically model this approach under laboratory conditions, a new test equipment was designed with the help of numerical analysis, i.e., Modified Stress Control Triaxial Equipment (MSCTE). The principal stress conditions occurring based on total stress in the post-cracking walls of tensile cracks with fully vertical and fully horizontal walls could be created under laboratory conditions with this test equipment. Tensile cracks developing in embankment dams were modeled with a circular hole formed in a cylindrical soil sample. Thus, by utilizing the mechanics of hollow cylindrical materials, the post-cracking wall stresses of tensile cracks can be explained by the stresses developing on the wall of the circular hole.

Anahtar Kelimeler

Crack, embankment dam, internal erosion, ansys workbench, triaxial stress

Kaynakça

• J. Lowe, Recent development in the design and construction of earth and rockfill dams, 10th International Congress on Large Dams, Montreal, Canada, 1970, pp. 11–23.
• S. Topçu, Kil çekirdekli kaya dolgu barajlarda hidrolik çatlama potansiyelinin tahmin edilmesi, DSİ Teknik Bülten 125 (2017) 1–7.
• M. Foster, R. Fell, M. Spannagle, The statistics of embankment dam failures and accidents, Canadian Geotechnical Journal 37 (5) (2000) 1000–1024.
• S. Topçu, Comparative analysis of internal erosion behaviour for fine grained soils under different stress state, Doctoral Dissertation Eskişehir Osmangazi University (2021) Eskişehir.
• United States of Burea of Reclamation (USBR), Design Standard No. 13. Embankment Dams, Protective Filters (2011), https://www.usbr.gov/tsc/techreferences/designstandards-datacollectionguides/finalds-pdfs/DS13-5.pdf, Accessed 17 Oct 2023.
• International Comission of Large Dams (ICOLD), Bulletin No. 95: Embankment Dams: Granular Filters and Drains – Review and Recommendations, Paris, 1994.
• H. Tosun, S. Topçu, Toprak Dolgu Barajlarda Hidrolik Çatlama, Uluslararası Katılımlı IV. Ulusal Baraj Güvenliği Sempozyumu, Elazığ, 2014, pp. 519–530.
• G. Hunter The deformation behaviour of embankment dams and landslides in natural and constructed soil slopes, Doctoral Dissertation The Universty of New South Wales (2003) Australia.
• R. Fell, M. A. Foster, J. Cyganiewicz, G. L. Sills, N. D. Vroman, R. R. Davidson, Risk analysis for dam safety: a unified method for estimating probabilities of failure of embankment dams by ınternal erosion and piping, URS Australia, Sdyney, 2008.
• Norwegian Geotechnical Institute (NGI), Jukla Sekundaerdam Lkkaasjer,Reparasjober,Pavisning av erosjonskanaler Gjennom Tetningskjernen, Internal Report 53600-1, Oslo, 1984.
• H. Bui, R. Fell, C. Song, Two and Three Dimensional Numerical Modelling of the Potential for Cracking of Embankment Dams during Construction, UNICIV Report 426, The Universty of New South Wales (2004) Sydney.
• J. G. Zhu, J. J. Wang, Investigation to arching action and hydraulic fracturing of core rock-fill dam, Proceedings of the 4th International Conference on Dam Engineering New Developments in Dam Engineering, Nanjing, 2004, pp. 1171–1180.
• J. J. Wang, Hydraulic Fracturing in Earth-Rock Fill Dam, Water Publication of China, China, 2012.
• S. Pells, R. Fell, Damage and Cracking of Embankment Dams by Earthquakes and the Implications for Internal Erosion and Piping, University of New South Wales, 2002.
• J. L. Shrerard, Influence of Soil Properties and Construction Methods on the Performance of Homogeneous Earth Dams, USBR Tech Memo No.645, Denver, 1953.
• P. Londe, La fissuration des Noveaux.Proc. 10th ICOLD, Montreal, vol. IV, 1970.
• F. C. Fong, W. J. Bennett, Transverse cracking in earth dams due to earthquakes, Proc. Western Regional Conference, American Society of State Dam Safety Officials, Red Lodge, 1995.
• K. He, C. Song, R. Fell, Numerical modelling of transverse cracking in embankment dams, Computers and Geotechnics 132 (2021) 104028.
• V. N. Nguyen, J. R. Courivaud, P. Pinettes, H. Souli, J. M. Fleureau, Using an improved jet-erosion test to study the influence of soil parameters on the erosion of a silty soil, Journal of Hydraulic Engineering 143 (8) (2017) 04017018.
• B. Burns, G. S. Ghataora, Internal erosion of kaolin, in A. J. Puppala, N. Hudyma, W. J. Likos (Eds.), Problematic Soils and Rocks and In Situ Characterization, Colorado, 2007, 1–8.
• H. J. Gibbs, A Study of erosion and tractive force characteristics in relation to soil mechanics properties, U. S. Department of Interior, Bureau of Reclamation, Colorado, Report No. EM-643, 1962.
• M. A. Tekinsoy, Zeminlerde kırılma ve denge (Mukavemet’de odömetre tekniği), Şırnak Üniversitesi Yayınları, Şırnak, 2018.
• E. G. Truscott, Behaviour of embankmemnt dams, Doctoral Dissertation University of London (1977) London.
• W. T. Lambe, Stress path method, ASCE Journal of the Soil Mechanics and Foundations Division 93 (6) (1967) 309–331.
• A. W. Bishop, V. K. Garga, Drained tension tests on London clay, Geotechnique 19 (2) (1969) 309–313.
• F. H. Kulhawy, T. M. Gurtowski, Load transfer and hydraulic fracturing in zoned dams, ASCE Journal of the Geotechnical Engineering Division 102 (9) (1976) 963–974.
• R. L. Sanchez, A. I. Strutynsky, M. L. Silver, Evaluation of the erosion potential of embankment core materials using the laboratory triaxial erosion test procedure (No. WES/TR/GL-83-4), Army Engineer Waterways Experiment Station Vicksburg Ms Geotechnical Lab, 1983.
• W. Fairbairn, Two lectures, on the construction of boilers, and on boiler explosions, with the means of prevention: Delivered before the Leeds’ Mechanics’ Institution, April 23 and 24, 1851: also a paper on the consumption of fuel and prevention of smoke, read before the British association for the advancement of science, Simpkin, Marshall, and Co., 1851.
• T. Stolarski, Y. Nakasone, S. Yoshimoto, Engineering analysis with ANSYS software, Butterworth-Heinemann, 2018.
• M. H. Farzin, R. J. Krizek, R. B. Corotis, Evaluation of modulus and poisson’s ratio from triaxial tests, Transportation Research Record 537 (1975) 69–80.
• J. L. Briaud, Introduction to soil moduli, Geotechnical News 19 (2) (2001) 54–58.
• W. T. Oh, S. K. Vanapalli, Relationship between Poisson’s ratio and soil suction for unsaturated soils, 5th Asia-Pacific Conference on Unsaturated Soils Bangkok, Thailand, 2011, 239–245.
• M. Ozen, Mesh Metric Spectrum Quality, California, Journal of Physics of Fluid 48 (2012) 236–267.