Kumların sıvılaşmasında rölatif sıkılık ve kesme birim deformasyonu etkisinin incelenmesi

Öz

Kohezyonsuz zeminlerin sıvılaşma potansiyeli, gerilme yaklaşımını kullanan SPT, CPT gibi arazi yöntemleri ve üç eksenli dinamik kesme, burulmalı kesme, rezonant kolon, bender eleman gibi laboratuvar deneyleri ile belirlenmektedir. Kumların sıvılaşma potansiyelinin tahmininde son zamanlarda, enerji kavramı kullanılmaya başlanmıştır. Bu yaklaşımda kullanılan başlıca parametreler, zeminin rölatif sıkılığı ve efektif gerilmedir. Bu çalışmada, Devirsel Basit Kesme Düzeneği kullanılmıştır. Bu çalışmada, kumların sıvılaşma enerjisinin belirlenmesinde, kesme birim deformasyonu oranı ve rölatif sıkılığın etkisi incelenmiştir. Çalışmada, temiz ince deniz kumu kullanılmıştır. Kum numuneleri 3 farklı rölatif sıkılıkta (Dr=%40, %55 ve %70); 4 ayrı düşey gerilme (σv= 50, 100, 200 ve 300 kPa) ve boşluk suyu basıncı (u= 25, 50, 75 ve 150 kPa) etkisinde bırakılmıştır. 3 ayrı kesme birim deformasyonu oranında (𝛶= %2, %3.5 ve %5) toplam 36 deney yapılmıştır. Deney örneklerine, tek eksenli 0.1 Hz frekansta harmonik yükleme uygulanmıştır. Çalışma sonucunda rölatif sıkılık, kesme birim deformasyonu oranı ve düşey gerilme şartlarının kumların sıvılaşma potansiyeline etkisi ince taneli deniz kumu için ortaya konmuştur. Kesme birim deformasyon oranındaki artış, sıvılaşma potansiyelini %3’lük oranda azaltmaktadır. Rölatif sıkılıktaki artış, kumun kesme direncini arttırmaktadır. Bu ise sıvılaşmayı geciktirmekte ve devir sayısında artışa neden olmaktadır.

Anahtar Kelimeler

• Devirsel basit kesme deneyi
• Boşluk suyu basıncı
• Kesme birim deformasyonu
• Sıvılaşma potansiyeli
• Düşey gerilme
• Rölatif sıkılık

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

Abstract

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 shear strain 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 (γ= 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

Kaynakça

1. [1] Towhata I. Geotechnical Earthquake Engineering. 1st ed. Berlin, Heidelberg, Germany, Springer-Verlag, 2008.
2. [2] Law KT, Cao YL, He GN. “An energy approach for assessing seismic liquefaction potential”. Canadian Geotechnical Journal, 27, 320-329, 1990.
3. [3] Figueroa J, Saada A, Liang L, Dahisaria N. “Evaluation of soil liquefaction by energy principles”. Journal of Geotechnical Engineering, 120(9), 1554-1569, 1994.
4. [4] Liang L. Development of an Energy Method for Evaluating the Liquefaction Potential of a Soil Deposit. PhD Dissertation. Case Western Reserve University, Cleveland, Ohio, USA, 1995.
5. [5] Cetin KO, Seed RB, Der-Kiureghian A, Tokimatsu K, Harder Jr F, Kayen RE, Moss RES. “Standard penetration test-based probabilistic and deterministic assessment of seismic soil liquefaction potential”. Journal of Geotechnical and Geoenvironmental Engineering, 130(12), 1314-1340, 2012.
6. [6] Berrill JB, Davis RO. “Energy dissipation and seismic liquefaction of sands: revised model”. Soils and Foundations, 25(2), 106-118, 1985.
7. [7] Kokusho T. “Liquefaction potential evaluation: energy-based method comparedto stress-based method”. 7th International Conference on Case Histories in Geotechnical Engineering, Chicago, Illinoise, USA, 29 April-4 May 2013.
8. [8] Amini PF, Noorzad R. “Energy-based evaluation of liquefaction of fiber-reinforced sand using cyclic triaxial testing”. Soil Dynamics and Earthquake Engineering, 104, 45-53, 2018.

9. [9] Jafarian Y, Towhata I, Baziar MH, Noorzad A, Bahmanpour A. “Strain energy based evaluation of liquefaction and residual pore water pressure in sands using cyclic torsional shear experiments”. Soil Dynamics and Earthquake Engineering. 35, 13-28, 2012.
10. [10] Seed HB, Lee KL. “Liquefaction of saturated sands during cyclic loading”. Journal of Soil Mechanics & Foundations Division, Proceedings of Amerikan Society of Civil Engineers, 92(6), 105-134, 1966.
11. [11] Hyodo M, Tanimizu H, Yasufuku N, Murata H. “Undrained cyclic and monotonic triaxial behavior of saturated loose sand”. Japan Society of Soil Mechanics and Foundation Engineering, Soils and Foundations, 34(1), 19-32, 1994.
12. [12] Green RA. Energy-Based Evaluation and Remediation of Liquefiable Soils. PhD Dissertation, Virginia Polytechnic Institute and State University, Blacksburg, VA, 2001.
13. [13] Seed HB, Idriss IM. “Simplified procedure for evaluating soil liquefaction potential”. Journal of the Soil Mechanics and Foundations Division, 97(8), 1249-1274, 1971.
14. [14] Youd TL, Idriss IM, “Liquefaction resistance of soils: summary report from the 1996-NCEER and 1998-NCEER/NSF workshops on evaluation of liquefaction resistance of soils”. Journal of Geotechnical and Geoenvironmental Engineering, 127(4), 297-313, 2001.
15. [15] Martin GR, Finn WDL, Seed HB. “Fundementals of liquefaction under cyclic loading”. Journal of Geotechnical and Geoenvironmental Engineering, 101(5), 423-438, 1975.
16. [16] Ishihara K and Yasuda S. “Sand liquefaction in Hollow Cylinder Torsion under irregular excitation”. Soils and Foundations, 15(1), 45-59, 1975.
17. [17] Boulanger RW, Idriss IM. “Probabilistic standard penetration test-based liquefaction-triggering procedure”. Journal of Geotechnical and Geoenvironmental Engineering, 138(10), 1185-1195, 2012.
18. [18] Moss RES, Seed RB, Kayen RE, Stewart JP, Der Kiureghian A, Cetin KO. “CPT based probabilistic and deterministic assessment of in situ seismic soil liquefaction potential”. Journal of Geotechnical and Geoenvironmental, 132, 1032-1051, 2006.
19. [19] Baziar MH, Jafarian Y. “Assessment of liquefaction triggering using strain energy concept and ANN model, capacity energy”. Soil Dynamics and Earthquake Engineering, 27, 1056-1072, 2007.
20. [20] Dobry R, Ladd RS, Yokel FY, Chung RM, Powell D. “Prediction of Pore Water Pressure Buildup and Liquefaction of Sands During Earthquakes by the Cyclic Strain Method”. National Bureau of Standards, Building Science Series, US Department of Commerce Report, Washington DC, USA, NBS-BSS-138/176, 1982.
21. [21] Alavi AH, Gandomi AH. “Energy-based numerical models for assessment of soil liquefaction”. Geoscience Frontiers, 3(4), 541-555, 2012.
22. [22] Seed HB. “Closure to soil liquefaction and cyclic mobility evaluation for level ground during earthquakes”. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 106(GT6), 720-724, 1980.
23. [23] Zhang W, Goh ATC, Zhang Y, Chen Y, Xiao Y. “Assessment of soil liquefaction based on capacity energy concept and multivariate adaptive regression splines”. Engineering Geology, 188, 29-37, 2015.
24. [24] Nemat-Nasser S, Shokooh A. “A unified approach to densification and liquefaction of cohesionless sand in cyclic shearing”. Canadian Geotechnical Journal, 16(4), 659-678, 1979.
25. [25] Towhata I, Ishihara K. “Shear work and pore water pressure in untrained shear”. Soils and Foundations, 25(3), 73-84, 1985.
26. [26] Hadush S, Yashima A, Uzuoka R. “Importance of viscous fluid characteristics in liquefaction induced lateral spreading analysis”. Computers and Geotechnics, 27, 199-224, 2000.
27. [27] Altun S. “Suya doygun kumların drenajsız koşullardaki davranışının tekrarlı yükler altında burulmalı kesme deney aleti ile incelenmesi”. DEÜ Mühendislik Fakültesi Fen ve Mühendislik Dergisi, 6(1), 139-152, 2004.
28. [28] Altun S, Ansal AM. “Anizotropik konsolide zeminlerin dinamik davranışı”. İMO Teknik Dergi, 16(2), 3523-3545, 2005.
29. [29] Ishihara K, Towhata I. “Sand response to cyclic rotation of principal stress directions as induced by wave loads”. Soils and Foundations, 23(4), 11-26, 1983.
30. [30] Japanese Geotechnical Society. “Method for Cyclic Torsional Shear Test on Hollow Cylindirical Specimens to Determine Deformation Properties of Soils”. Standarts of Japanese Geotechnical Society for Laboratory Shear Test, JGS 0543, Japan, 2000.
31. [31] Japanese Geotechnical Society. “Preparation of hollow Cylindirical Soil Specimens for Torsional Shear Tests”. Standarts of Japanese Geotechnical Society for Laboratory Shear Test, JGS 0550, Japan, 1998.
32. [32] Japanese Geotechnical Society. “Method for Torsional Shear Test on Hollow Cylindirical Specimens”. Standarts of Japanese Geotechnical Society for Laboratory Shear Test, JGS 0551, Japan, 1998.
33. [33] Ishihara K. Soil Behavior in Earthquake Geotechnics. 2nd ed. New York, USA, Oxford University Press, 1996.
34. [34] Elibol B. Kısmi Doygun Kumların Tekrarlı Yükler Altındaki Davranışları. Yüksek Lisans Tezi, İstanbul Teknik Üniversitesi, İstanbul, Türkiye, 2005.
35. [35] Ural N, Özocak A, Önalp A. “Dinamik üç eksenli deneyde frekansın etkisi”. 6. Ulusal Deprem Mühendisliği Konferansı, İstanbul, Türkiye, 16-20 Ekim 2007.
36. [36] Orhan M, Ateş A. “Rölatif sıkılığın Saruhanlı (Manisa) ilçesi zeminlerinin sıvılaşmasına etkisinin dinamik üç eksenli deneyi ile araştırılması”. Süleyman Demirel Üniversitesi Teknik Bilimler Dergisi, 2(1), 26-41, 2012.
37. [37] Bilge HT, Çetin KÖ. “Sıvılaşma tetikleme analizlerinde düşey efektif gerilme etkisinin performans esaslı olarak belirlenmesi”. Zemin Mekaniği ve Temel Mühendisliği 15. Ulusal Kongresi, Ankara, Türkiye, 16-17 Ekim 2014.
38. [38] Nateghi A. Numerical Modelling of Sand Behavior Under Cyclic Simple Shear Tests in a Special Liquefaction Box. MSc Thesis, Istanbul Technical University, Istanbul, Turkey, 2015.
39. [39] Monkul MM, Etminan E, Şenol A. “Influence of coefficient of uniformity and bases and gradation on static liquefaction of loose sands with silt”. Soil Dynamics and Earthquake Engineering, 89, 185-197, 2016.
40. [40] Polito C, Green RA, Dillon E, Sohn, C. “Effect of load shape on relationship between dissipated energy”. Canadian Geotechnical Journal, 50, 1118-1128, 2013.
41. [41] Baziar MH, Jafarian Y, Shahnazari H, Movahed V, Tutunchian MA. “Predictionof strain energy-based liquefaction resistance of sand-silt mixtures: An evolutionary approach”. Computers and Geosciences. 37(11), 1883-1893, 2011.
42. [42] Arab A, Shahrour I, Lancelot L. “A laboratory study of liquefaction of partially saturated sand”. Journal of Iberian Geology, 37(1), 29-36, 2011.
43. [43] Kammerer A, Pestana JM. “Undrained Response of Monterey 0/30 Sand Under Multidirectional Cyclic Simple Shear Loading Conditions”. University of California, Berkeley, USA, Geotechnical Engineering Report No UCB/GT/02-01, 2002.
44. [44] Özçelik Ş. Kumlu Zeminlerin Sıvılaşma Enerjisinin Laboratuvarda Belirlenmesinde Numune Boyutunun Etkisinin Araştırılması. Yüksek Lisans Tezi, Pamukkale Üniversitesi, Denizli, Türkiye, 2019.
45. [45] Özlen N. “Ilgın (Konya) Yerleşim Alanı Zeminlerinin Jeoteknik Özelliklerinin Araştırılması”. Yüksek Lisans Tezi, Konya Teknik Üniversitesi, Konya, Türkiye, 2019.
46. [46] American Society for Testing and Materials. “Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table”. ASTM D4253-16. ASTM International, West Conshohocken, USA, 2016.
47. [47] Lo Presti DCF, Pedroni S, and Crippa V. "Maximum dry density of cohesionless soils by pluviation and by ASTM D4253-83: A Comparative Study". Geotechnical Testing Journal. 15(2), 180-189, 1992.
48. [48] American Society for Testing and Materials. “Standard Test Methods for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density”. ASTM D4254-16. ASTM International, West Conshohocken, USA, 2016.
49. [49] American Society for Testing and Materials. “Standart Method of Test for Sieve Analysis of Fine and Coarse Aggregates”. ASTM C136. ASTM International, West Conshohocken, USA, 2006.