اثر عرض گسیختگی بر تغییر مکان ماندگار لرزه ای شیب‌های خاکی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 پژوهشکده ژئوتکنیک، پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزله، تهران، ایران

2 دانشکده مهندسی عمران، دانشگاه سمنان، سمنان، ایران

چکیده

مدل بلوک لغزنده‌ی نیومارک برای محاسبه تغییر مکان ماندگار شیب‌ها و سدهای خاکی در برابر زلزله بکار می‌رود و به دلیل سادگی و دقت نسبتاٌ مناسب مورد توجه بسیاری از مهندسان قرار گرفته است. محدودیت‌هایی همانند عدم در نظر گرفتن دوران گوه‌ی گسیختگی و همچنین پاسخ سیستم این روش توسط بسیاری از محققین اصلاح شده است. در این مقاله اثر عرض توده لغزنده بر مقدار تغییرمکان ماندگار مورد ارزیابی قرار می‌گیرد و شتاب گسیختگی با در نظر گرفتن این اثر که معرف بعد سوم گوه‌ی گسیختگی است اصلاح می‌شود. با توجه به شتاب گسیختگی اصلاح شده، تغییر مکان ماندگار توسط تحلیل‌های غیر وابسته و وابسته محاسبه شده است. نتایج نشان می‌دهد که عرض گسیختگی بر روی تغییر مکان ماندگار موثر می‌باشد. به طوری که در یک طول لغزش ثابت، هرچه عرض گسیختگی کاهش یابد شتاب گسیختگی افزایش یافته و اختلاف بین روش غیر وابسته (یا وابسته) اصلاح شده با تحلیل غیر وابسته (یا وابسته)افزایش می‌یابد.

کلیدواژه‌ها


عنوان مقاله [English]

Effect of slip width on the permanent displacement of earth slopes

نویسندگان [English]

  • Y. Jafarian 1
  • A. Lashgari 2
1 Geotechnical Engineering Research Center, International Institute of Earthquake Engineering and Seismology, Tehran, Iran
2 Department of Civil Engineering, Semnan University, Semnan, Iran
چکیده [English]

Newmark sliding block method is commonly used for estimating earthquake-induced permanent displacement of earth slopes and embankments. Since this method is a simplified dynamic analysis procedure with acceptable accuracy, it has been received considerable attention among the geotechnical practitioners. However, it has some shortcomings such as neglecting system response and sliding mass rotation. Hence, researchers have proposed modified procedure to enhance the realistic features of this method. The effect of sliding mass rotation, which sets the block in a gentler condition, was previously considered by continuous increment of yield acceleration. Since the sliding mass is three dimensional in reality, smaller permanent displacement is expected when the width of block is accounted for. In this paper, width of the rotating-sliding mass is taken into account in the coupled and decoupled solution of block sliding equations. The results show that the width of the slip zone is effective on the resulting displacements. With a constant slip length, whatever slip width is reduced, yield acceleration increases and consequently difference between the modified decoupled (or modified coupled) and decoupled (or coupled) increases.

کلیدواژه‌ها [English]

  • Earth slopes
  • Permanent displacement
  • Rigid block method
  • Decoupled analysis
  • Coupled analysis
[1] N. M., Newmark; Effects of Earthquakes on Dams and Embankments, Geotechnique, Vol. 15, No. 2, pp. 139-160, 1965.
[2] J. S., Lin; R. V., Whitman; Decoupling Approximation to the Evaluation of Earthquake–Induced Plastic Slip in Earth Dams, Earthquake Engineering Structural Dynamics, Vol. 11, No. 5, pp. 667-678, 1983.
[3] A. K., Chopra; L., Zhang; Earthquake–Induced Base Sliding of Concrete Gravity Dams, Journal of Structural Engineering, ASCE, Vol. 117, No. 12, pp. 3698-3719,1991.
[4] S. L., Kramer; M. W., Smith; Modified Newmark Model for Seismic Displacements of Compliant Slopes, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 123, No. 7, pp. 635-644, 1997.
[5] E. M., Rathje; N., Abrahamson; J. D., Bray; Simplified Content Estimates of Earthquake Ground Motions, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 124, No. 2, pp. 150-159, 1998.
[6] E. M., Rathje; J. D., Bray; An Examination of Simplified Earthquake–Induced Displacement Procedures for Earth Structures, Canadian Geotechnical Journal, Vol. 36, No.1, pp. 72-87, 1999.
[7] C. A., Stamatopoulos; Sliding System Predicting Large Permanent Co–seismic Movements of Slope, Earthquake Engineering Structural Dynamics, Vol. 25, No. 10, pp.1075-1093, 1996.
[8] M. H., Baziar; H., Rezaeipour; Y., Jafarian; Decoupled Solution for Seismic Permanent Displacement of Earth Slopes Using Deformation-Dependent Yield Acceleration, Journal of Earthquake Engineering, Vol.16, No. 7, pp. 917-936, 2012.
[9] D., Pradel; P. M., Smith; J. P., Stewart; G., Raad; Case History of Landslide Movement During the Northridge Earthquake, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 131, No. 11, pp.1360-1369, 2005.
[10] F. I., Makdisi; H. B., Seed; Simplified Procedure for Estimating Dam and Embankment Earthquake–Induced Deformations, Journal of Geotechnical Engineering, ASCE, Vol. 104, No. GT7, pp. 849 867, 1987.
[11] E. M., Rathje; J. D., Bray; Nonlinear Coupled Seismic Sliding Analysis of Earth Structures, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 126, No. 11, pp. 1002-1014, 2000.
[12] J. D., Bray; T., Travasarou; Simplified Procedure for Estimating Earthquake-Induced Deviatoric Slope Displacements, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 133, No. 4,pp. 381-392, 2007.
[13] E. M., Rathje; G. A., Antonakos; Unified Model for Predicting Earthquake-Induced Sliding Displacements of Rigid and Flexible Slopes, Soil Dynamics and Earthquake Engineering, Vol. 122, No. 12, pp. 51-60, 2011.
[14] N. M., Newmark; A Method for Computation for Structural Dynamics, Journal of the Engineering Mechanics Division, ASCE, Vol. 85, No. 3, pp. 67-94,1959.