Konsol istinat duvarlarının 2018 TBDY'ye göre irdelenmesi = Examination of console retaining walls according to 2018 TBER

Abstract

Türkiye'de sık gündeme gelen istinat duvarı yıkılma olayları bu tezin çıkış noktası olmuştur. Tez kapsamında öncelikle istinat yapıları hakkında genel bilgi verilip statik ve dinamik durumdaki hesaplama yöntemleri anlatılmıştır. Araştırma kapsamında yıkılan duvar örnekleri fotoğraflardan incelenip yıkılma nedenleri irdelenmiştir. Türkiye Bina Deprem Yönetmeliğinde değişen dinamik hesaplama bölümünün eski yönetmelikle (2018 ve 2007) karşılaştırılabilmesi için örnek problem üzerinde elle çözüm yapılmıştır. Bir Türk yazılımı olan istCAD ile duvar yüksekliğinin (H) 6,50 m, temel gömme derinliğinin (Df) 1,50 m, zemin eğiminin (α) 15°, zemin arkası sürşarj yükünün (q) 10 kPa olduğu ve yer altı su seviyesinin mevcut olmadığı durumda modelleme yapılmıştır. Elle çözülen modelde elde edilen sonuçlar eski ve yeni yönetmelik sonuçlarıyla karşılaştırılmıştır. IstCAD programında ayrıca yer altı su seviyesinin, duvar yüksekliğinin, dolgu malzemesi özelliğinin, duvar gövdesinin konumunun ve zemin eğiminin etkisinin betonarme konsol istinat duvarının stabilitesine ve kesit tesirlerine etkisi statik ve dinamik durumlarda irdelenmiştir. Parametrelerin etkilerine göre stabiliteyi bozan durumlarda istinat yapısının boyutları güncellenmiş ve kesit tesirlerindeki değişim incelenmiştir. Bir diğer geoteknik yazılımı olan Plaxis 2D ile de ana modelin (H: 6,50 m, Df: 1,50 m, α: 15°, q: 10 kPa, Y.A.S.S.: yok) statik ve dinamik analizi gerçekleştirilmiştir. Ayrıca 6,50 m duvar yüksekliği için toplam 64 adet kombinasyona ait modellerde deformasyonlar ve kesit tesirleri hesaplanmıştır. Bu kombinasyonlara ait modellerde temel gömme derinliğinin, sürşarj yükünün, yer altı su seviyesinin ve duvar üstündeki zemin yüzey eğiminin etkisi irdelenmiştir. 4,50 metreden başlayarak 8,50 metre yüksekliğe kadar olan 5 adet betonarme konsol istinat yapısının metrajı istCAD programından elde edilerek Çevre, Şehircilik ve İklim Bakanlığı'nın 07/2022 tarihli birim fiyatlarıyla duvarların yaklaşık toplam maliyeti hesaplanmıştır. Elde edilen verilere göre yeni yönetmelikle dinamik hesap sonucu duvar boyutlarının arttığı yapılan karşılaştırmalarla ortaya konulmuştur. IstCAD ile yapılan analizler sonucunda yer altı su seviyesinin yıkıcı etkisi ortaya konmuştur. Dolgu malzemesi olarak geçirimliliği ve kayma direnci açısı düşük bir malzeme olan kilin kullanılması durumunda duvara etki eden yanal basınçların artması ile duvarın gövdesindeki kesit tesirlerinin iki katından fazla arttığı gözlenmiştir. Ana model Plaxis 2D programında modellenmiş ve duvar üstündeki zemin eğiminin 0°'den 15°ye artması ile toplam deformasyon ve yatay deformasyon oranlarının, kesit tesirlerinde ise ciddi şekilde artış olduğu gözlenmiştir. Plaxis 2D programında psödostatik analiz ile 0,25g, -0,25g, 0,40g ve -0,40g ivmeleri ana modele etki ettirilmiş ve 0,40g ivmede model oturmalardan kaynaklı göçmeye uğramıştır.

Within the scope of the thesis, first of all, general information about retaining structures is given, and calculation methods in static and dynamic situations are explained. Lateral earth pressures acting on the wall in static condition Rankine and Coulomb pressure theories and Mononobe-Okabe and Seed-Whitman methods, which are dynamic earth pressures acting in dynamic condition, are included in the thesis. Within the scope of the study, in which the news of the collapse of retaining walls in a static condition, which has recently come to the fore in various regions of Turkey, is investigated, the estimated causes of collapse were investigated by examining these walls from photographs. In the photographs, it was observed that the walls collapsed after a rain. It is estimated that the retaining walls collapsed as a result of the use of granular and impermeable fillings that do not have good drainage. The points to be considered in the construction of retaining walls are explained on the faults seen in the collapsed walls. In order to reveal the differences between the new earthquake code and the changing dynamic calculation method, a manual solution was made and the results were compared with the old earthquake code. Studies on cantilever retaining walls in the literature are included in the thesis. The interface presentation of the two software used in the study was supported by visuals. The walls were modeled in two different retaining wall modeling programs and the results were examined comparatively. With the Turkish-made istCAD software, wall height (H) 6.50 m, foundation burial depth (Df) 1.50 m, ground slope (α) 15°, back-ground surcharge load (q) 10 kPa and groundwater level modeling were made. The results were compared with the old and new regulation results solved manually. In the IstCAD program, the effects of groundwater level, wall height, infill material, position of the wall body and ground slope on the cross-sectional effects of the reinforced concrete cantilever retaining wall were investigated in static and dynamic conditions. The dimensions of the retaining structure have been updated and the variation of the cross-section effects in cases where the stability has deteriorated due to the effects of the parameters has been examined. Static and dynamic analysis of the main model (H: 6.50 m, Df: 1.50 m, α: 15°, q: 10 kPa, U.W.L: none) was done with Plaxis 2D, another geotechnical software. In Plaxis, a total of 64 combinations were created for the main model, and the variation of the deformation and cross-section effects on the wall was investigated. The effects of frost level (basic burial depth), surcharge load, groundwater level and ground surface slope on these combinations were investigated. The approximate total cost of the walls has been calculated with the unit prices of the Ministry of Environment, Urbanization and Climate dated 07/2022, by taking the quantity data of 5 reinforced concrete cantilever retaining structures from 4.50 meters to 8.50 meters from the istCAD program. It has been observed that the cost increases as the wall dimensions increase. According to the data obtained, it was revealed by the comparisons that the dynamic account values increased with the new arrangement. It is thought that this increase is due to the fact that the ground effects are included in the calculation with the new earthquake code and the SDS (short period design acceleration spectral coefficient) is taken into account. As a result of the wall analyzes made with istCAD, it has been found that the destructive effect of the groundwater level, that the wall can collapse when an impermeable filling is used, and that the slope of the ground imposes excessive loads on the wall. It has been observed that the cross-sectional effects on the wall body increase more than twice as the lateral pressures acting on the wall increase when used in clay filling material with low shear strength angle, which is an undrained material. The main model was modeled in the Plaxis 2D program and by increasing the ground slope from 0° to 15°, the overall deformation, horizontal deformation rate decreased significantly, while the section effects increased significantly. It was observed that the deformation data decreased in all cases as the foundation depth increased in Plaxis. It has been observed that the surcharge load can collapse the retaining wall in cases where the foundation depth is insufficient. Since the heel of the retaining wall is modeled as 1 meter, the models collapsed in all cases where the groundwater level was at the height of the wall. With Plaxis 2D printing pseudostatic analysis, 0.25g, -0.25g, 0.40g and -0.40g accelerations were applied to the main model and at 0.40g acceleration, the model collapsed due to settlements.