Pamukkale Univ Muh Bilim Derg. 2021; 27(3): 431-440 | DOI: 10.5505/pajes.2020.53138

Kumlarýn sývýlaþmasýnda rölatif sýkýlýk ve kesme birim deformasyonu etkisinin incelenmesi

Turgay Beyaz¹, Kamil Kayabalý², Yetiþ Bülent Sönmezer^3
1Pamukkale Üniversitesi Mühendislik Fakültesi Jeoloji Mühendisliði Bölümü, Denizli
²Ankara Üniversitesi Mühendislik Fakültesi Jeoloji Mühendisliði Bölümü, Ankara
³Kýrýkkale Üniversitesi Mühendislik Fakültesi Ýnþaat Mühendisliði Bölümü, Kýrýkkale

Kohezyonsuz zeminlerin sývýlaþma potansiyeli, gerilme yaklaþýmýný kullanan SPT, CPT gibi arazi yöntemleri ve üç eksenli dinamik kesme, burulmalý kesme, rezonant kolon, bender eleman gibi laboratuvar deneyleri ile belirlenmektedir. Kumlarýn sývýlaþma potansiyelinin tahmininde son zamanlarda, enerji kavramý kullanýlmaya baþlanmýþtýr. Bu yaklaþýmda kullanýlan baþlýca parametreler, zeminin rölatif sýkýlýðý ve efektif gerilmedir. Bu çalýþmada, Devirsel Basit Kesme Düzeneði kullanýlmýþtýr. Bu çalýþmada, kumlarýn sývýlaþma enerjisinin belirlenmesinde, kesme birim deformasyonu oraný ve rölatif sýkýlýðýn etkisi incelenmiþtir. Çalýþmada, temiz ince deniz kumu kullanýlmýþtýr. Kum numuneleri 3 farklý rölatif sýkýlýkta (Dr=%40, %55 ve %70); 4 ayrý düþey gerilme (σv= 50, 100, 200 ve 300 kPa) ve boþluk suyu basýncý (u= 25, 50, 75 ve 150 kPa) etkisinde býrakýlmýþtýr. 3 ayrý kesme birim deformasyonu oranýnda (𝛶= %2, %3.5 ve %5) toplam 36 deney yapýlmýþtýr. Deney örneklerine, tek eksenli 0.1 Hz frekansta harmonik yükleme uygulanmýþtýr. Çalýþma sonucunda rölatif sýkýlýk, kesme birim deformasyonu oraný ve düþey gerilme þartlarýnýn kumlarýn sývýlaþma potansiyeline etkisi ince taneli deniz kumu için ortaya konmuþtur. Kesme birim deformasyon oranýndaki artýþ, sývýlaþma potansiyelini %3’lük oranda azaltmaktadýr. Rölatif sýkýlýktaki artýþ, kumun kesme direncini arttýrmaktadýr. Bu ise sývýlaþmayý geciktirmekte ve devir sayýsýnda artýþa neden olmaktadýr.

Anahtar Kelimeler: Devirsel basit kesme deneyi, boþluk suyu basýncý, kesme birim deformasyonu, sývýlaþma potansiyeli, düþey gerilme, rölatif sýkýlýk

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Investigation of the effect of the relative density and shear strain on liquefaction of sands

Turgay Beyaz¹, Kamil Kayabalý², Yetiþ Bülent Sönmezer^3
1Department of Geology Engineering, Pamukkale University, Denizli, Turkey
²Department of Geology Engineering, Ankara University, Ankara, Turkey
³Department of Civil Engineering, Kirikkale University, Kirikkale, Turkey

Liquefaction potential of non-cohesive soils is determined by field tests such as SPT, CPT, which use the stress approach, and laboratory tests such as three-dimensional dynamic shear, torsional shear, resonant column, and bender element tests. Recently, the approach of energy has been used to estimate the liquefaction potential of sands. The main parameters used in this approach are relative density and effective stress of the ground. In this study, Cyclic Simple Shear Test arrangement is used. In this study, the effect of deformation rate and relative density on the liquefaction energy of the sands were investigated. In the study, clean fine marine sands were used. In this study, 3 different relative densities for a sand sample (Dr= 40%, 55% and 70%); 4 different stresses (σv= 50, 100, 200 ve 300 kPa), and pore water pressure (u= 25, 50, 75 ve 150 kPa). Totally of 36 experiments were performed in and 3 different deformation rates ( = 2%, 3.5%, and 5%). The harmonic loading was applied to the experimental samples at a frequency (f) of 0.1 Hz. The effect of relative density, deformation rate and vertical stress conditions on the liquefaction energy of sands has been demonstrated for a type of fine-grained clean sea sand. The increase in the shear strain rate reduces the liquefaction potential by about 3%. The increase in relative density, increases the shear resistance of the sand. This delay liquefaction and causes an increase in the number of cycles.

Keywords: Cyclic simple shear test, pore pressure, shear strain, liquefaction potential, vertical stress, relative density

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