EFFECTIVE STRESS BASED NUMERICAL ANALYSIS OF LATERAL DEFORMATIONS DUE TO CYCLIC MOBILITY

Abstract

Cyclic mobility is a dynamic soil behaviour observed in saturated cohesionless soils under dynamic loads in which large amounts of shear deformation is accumulated after initial liquefaction and gives way to great lateral displacements. In this paper, one dimensional site response analyses are carried out on medium and verd dense sand profiles under sinuzoidal lateral acceleration in order to investigate numerically the development of cyclic mobility. The analyses are performed by using the nonlinear finite element method in OPENSEES framework and the cyclic mobility behaviour is represented by an effective stress based model called PDMY (Pressure Dependent Multi-Yield Surface Plasticity ) model. The results of the study showed that the development of cyclic mobility behaviour is strongly dependent on the relative density and initial effective stress conditions of the sand stratum, driving shear stresses, residual strength and the duration, frequency and the amplitude of the dynamic load

Keywords

• Liquefaction, Flow liquefaction, Cyclic mobility

ÇEVRİMSEL HAREKETLİLİK DAVRANIŞINA BAĞLI YANAL ZEMİN DEFORMASYONLARININ EFEKTİF GERİLME TABANLI SAYISAL ANALİZİ

Abstract

Çevrimsel hareketlilik, dinamik yükler altındaki suya doygun kum zeminlerde, sıvılaşma meydana geldikten sonra kayma deformasyonlarının birikmesi sonucunda yüksek düzeylerde yanal yerdeğiştirmelerin oluşmasına neden olan dinamik bir zemin davranışıdır. Bu çalışmada, çevrimsel hareketlilik davranışının oluşum sürecini sayısal olarak ortaya koymak amacı ile orta sıkı ve çok sıkı suya doygun kum tabakalarına uygulanan sinüzoidal yanal yer ivmesi altında bir boyutlu zemin tepkisi analizleri gerçekleştirilmiştir. Yapılan parametrik çalışmalarda sayısal analiz yöntemi olarak doğrusal olmayan sonlu elemanlar yöntemi, çevrimsel hareketlilik davranışının temsil edilebilmesi için ise efektif gerilme tabanlı bir zemin modeli olan PDMY (Pressure Dependent Multi-Yield Surface) plastisite modeli kullanılmıştır. Analizler OPENSEES sonlu eleman açık kod ortamında gerçekleştirilmiştir. Analizler sonucunda kum zeminin sıkılığı, başlangıç efektif gerilme durumu, dinamik yükleme öncesinde maruz kaldığı statik kayma gerilmeleri, rezidüel kayma dayanımı ile dinamik yüklemenin süresi, frekansı ve genliğinin çevrimsel hareketlilik davranışı üzerinde büyük ölçüde etkili oldukları görülmüştür.

Keywords

• Sıvılaşma, Akma sıvılaşması, Çevrimsel hareketlilik

References

1. K. Arulanandan, R. F. Scott edt. (1994): “Verification of Numerical Procedures for the Analysis of Soil Liquefaction Problems”, Cilt 1-2.
2. J. P. Bardet, N. Mace, T. Tobita (1999): “Liquefaction-Induced Ground Deformation and Failure”, Rapor PEER/PG&E, Task 4A-Faz 1, Southern California Üniversitesi.
3. L. C. Baynes (2005): “An Evaluation of Free Field Liquefaction Analysis Using Opensees”, Yüksek Lisans Tezi, Washington Üniversitesi, İnşaat ve Çevre Müh. Bölümü.
4. L. F. Bonilla, R. J. Archuleta, D. Lavallee (2005): “Hysteretic and Dilatant Behaviour of Cohesionless Soils and their Effects on Nonlinear Site Response: Field Data Observations and Modelling”, Bulletin of the American Society of America, Cilt 95, No. 6, sf. 2373- 2395.
5. H. G. Cooke (2000): “Ground Improvement For Liquefaction Mitigation At Existing Highway Bridges”, Doktora Tezi, Virginia Polytechnic Institute and State Universitesi.
6. A. Elgamal, Z Yang, E. Parra (2002): “Computational Modeling of Cyclic Mobility and Post- Liquefaction Site Response”, Soil Dynamics and Earthquake Engineering, Cilt 22, sf. 259- 271.
7. A. Elgamal, Z. Yang, E. Parra, A. Ragheb (2003): “Modeling of Cyclic Mobility in Saturated Cohesionless Soils”, International Journal of Plasticity, Cilt 19, sf. 883-905.
8. S. Iai, Y. Matsunaga, T. Kameoka (1990): “Strain Space Plasticity Model For Cyclic Mobility”, Port and Harbour Research Institute Raporu, Cilt 29,No. 4.

9. S. Iai (1991): “A Strain Space Multiple Mechanism Model for Cyclic Behaviour of Sand and its Application”, Earthquake Engineering Research Note, No:43, Earthquake Engineering Research Group Port And Harbour Research Institute, Ministry of Transport, Japan.
10. S. L. Kramer, A. Elgamal (2001): “Modelling Soil Liquefaction Hazards for Performance- Based Earthquake Engineering”, PEER Raporu 2001/13, Pacific Earthquake Engineering Research Center, College of Engineering, California Üniversitesi.
11. S. L. Kramer (1996): “Geotechnical Earthquake Engineering”, Prentice Hall, New Jersey.
12. R. L. Kuhlmeyer, J. Lysmer (1973): “Finite Element Method Accuracy for Wave Propagation Problems”, Journal of the Soil Mech. and Foundation Division, Cilt 99, No. 5, sf. 421-427.
13. S. Lenart (2008): “The Response of Saturated Soils To A Dynamic Load”, Acta Geotechnica Slovenica, No. 1.
14. S. Mazzoni, F. Mc Kenna, G. L: Fenves (2004): “OpenSees Command Language Manual in Preparation”, OpenSees and NEESgrid Simulation Component User Workshop, Pacific Earthquake Engineering Research Center, Richmond, CA., Pacific Earthquake Engineering Research Center Web Site, http://opensees.berkeley.edu.
15. W. F. Marcuson, M. Hynes, A. G: Franklin /2007): “Seismic Analysis and Analysis of Embankment Dams: The State of Practice”, The Donald M. Bermister Lecture, The Department of Civil Engineering and Engineering Mechanics, Columbia Universitesi.
16. E. Naesgaard, P. M. Byrne (2007): “Flow Liquefaction Simulation Using A Combined Effective Stress-Total Stress Model”, 60th. Canadian Geotechnical Conference, Canadian Geotechnical Society, Ottawa, Ontario.
17. M. Y. Özkan (1998): “A Review of Considerations on Seismic Safety of Embankments and Earth and Rock-Fill Dams”, Soil Dynamics and Earthquake Engineering, Cilt 17, sf. 439- 458.
18. E. Parra, (1996): “Numerical Modelling of Liquefaction and Lateral Ground Deformation Including Cyclic Mobility and Dilation Response in Soil Systems”, Doktora Tezi, Department of Civil Engineering, Rensselaer Polytechnic Institute, Troy, NY.
19. T. Sano (1916): “Aseismic Design of Buildings (I)”, Report of Earthquake Disaster Prevention Investigation Council, 83A.
20. R. B. Seed, K. O. Çetin, R. Moss, A. Kammerer, J. Wu, M. Pestana, M. F. Riemer, R. B. Sancio, J. D. Bray, R. E. Kayen, A. Faris (2003) “Recent Advances In Soil Liquefaction Engineering-A Unified and Consistent Framework”, 26. Annual ASCE Los Angeles Geotechnical Spring Seminar, Keynote Presentation, H.M.S. Queen Mary, Long Beach, California.
21. I. M. Smith (1994): “An Overview of Numerical Procedures Used in the VELACS Project”, Proc. Numerical Procedures for the Analysis of Soil Liquefaction Problems, Cilt 2, sf. 1321-1328.
22. M: Taiebat, H: Shahir, A. Pak (2007): “Study of Pore Pressure Variation During Liquefaction Using Two Constitutive Models For Sand”, Soil Dynamics and Earthquake Engineering, Cilt 27, No.1, sf. 60-72.
23. M. Tonaroğlu (2006): “Sıvılaşmanın Nümerik Yöntemlerle Modellenmesi”, Doktora Tezi, Yıldız Teknik Üniversitesi, Fen Bilimleri Enstitüsü.
24. I. Towhata (2005): “Development of Geotechnical Earthquake Engineering In Japan”, Heritage Lecture, 16. ICSMGE, Osaka, Japan.
25. Z. Yang, A. Elgamal, E. Parra (2003): “A Computational Model for Liquefaction and Associated Shear Deformation”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Cilt 129, No. 12.
26. Z. Yang (2000): “Numerical Modeling of Earthquake Site Response Including Dilation and Liquefaction”, Doktora Tezi, Columbia Universitesi.