NONPLASTİK SİLT KUM KARIŞIMLARINDA BOOTSTRAP YÖNTEMİ İLE BOŞLUK SUYU BASINCI OLUŞUMUNUN DEĞERLENDİRİLMESİ

Yıl 2018, Cilt: 7 Sayı: 1, 197 - 205, 31.01.2018

Eyyüb Karakan , Selim Altun

https://doi.org/10.28948/ngumuh.386530

Öz

   Bu
çalışmanın temel amacı, tekrarlı yükler altında nonplastik silt kum
karışımlarının boşluk suyu basıncı üretimini literatürdeki üç farklı modeli
kullanarak incelemektir. Boşluk suyu basıncı oluşumunda, kumlu zeminlerde silt
içeriğinin etkisini araştırmak amacıyla dinamik üç eksenli deneyler
yapılmıştır. Deneylerde sıvılaşma kriteri olarak, 200 çevrimdeki değer ya da
birincil sıvılaşma başlangıcından hangisi daha önce gerçekleşir ise, o durum
göz önüne alınmıştır. Altı farklı silt içeriğinde (FC=%0-100) hazırlanan
örneklerden, farklı tekrarlı gerilme genliği oranlarında aşırı boşluk suyu
basıncı üretiminin ölçülmesi için gerilme kontrollü dinamik üç eksenli deneyler
gerçekleştirilmiştir. Deneyler D_r=%25-50 rölatif sıkılıkta ve 100
kPa efektif çevre gerilmesi altında yapılmıştır. Deney sonuçları siltli
kumların drenajsız dinamik koşullar altında ne denli etkilendiğini bulmak için
kullanılmıştır. Seed ve ark. [3], Booker ve ark. [2] ve Polito ve ark. [8]
boşluk suyu basıncı üretimi model sonuçları çalışma kapsamında sunulmuştur.
Boşluk suyu basınçları model katsayısı a,
silt içeriği, rölatif sıkılık ve tekrarlı gerilme genliği oranına bağlı olarak
tahmin edilmeye çalışılmıştır.

Anahtar Kelimeler

Boşluk suyu basıncı, nonplastik silt–kum karışımı, dinamik üç eksenli deney, bootstrap yöntemi

CYCLIC PORE WATER PRESSURE GENERATION IN NON-PLASTIC SILT-SAND MIXTURES

Öz

   The aim of
this paper is to evaluate the applicability of the available three different
models to predict excess pore water pressure generation in non-plastic silty
sand mixtures during cyclic loading. Cyclic triaxial tests were performed to
investigate the effect of silt content on the pore pressure generation in sand.
These tests were carried to 200 cycles or to onset of initial liquefaction,
whichever occurred first. Several stress-controlled cyclic triaxial tests were
performed to measure excess pore water pressure generation at different levels
of cyclic stress ratios for the specimens prepared at six different silt
contents (FC=0% to 100%). The specimens were tested under 100 kPa confining
pressures at two relative densities of 25% and 50%. Results of these tests were
used to investigate the behavior of silty sands under undrained cyclic triaxial
testing conditions. Seed et al. [3], Booker et al. [2] and Polito et al. [8]
pore water pressure generation models based on test results are also presented in
this paper. An attempt to estimate the pore pressure model coefficient a as a function of silt content, relative density, cyclic stress ratio
was made.

Anahtar Kelimeler

Pore water pressure, non-plastic silt-sand mixtures, cyclic triaxial tests, bootstrap method

Kaynakça

• [1] LEE, K.L., A. ALBAISA., “Earthquake Induced Settlements in Saturated Sands”, J. Geotech. Eng. Div., ASCE, 100(4), 387-406, 1974.
• [2] BOOKER, J.R., RAHMAN, M. S., SEED, H.B., “A Computer Program for the Analysis of Pore Pressure Generation and Dissipation During Cyclic or Earthquake Loading”, Rep. No. EERC 76-24, Earthquake Engineering Research Center, Univ. of California at Berkeley, California, USA, 1976.
• [3] SEED, H.B., MARTIN, P.P., LYSMER J., “Pore Water Pressure Change During Soil Liquefaction”, J. Geotech. Eng. Div., ASCE, 102(4), 323-346, 1976.
• [4] ISHIHARA, K., “Stability of Natural Deposits During Earthquakes”, 11th International Conference on Soil Mechanics and Foundation Engineering, 321–376. San Francisco, CA, USA, 1985.
• [5] EVANS, M. D., ZHOU, S., “Liquefaction Behavior of Sand-Gravel Composites”, J. Geotech. Eng. Div., 121, 3, 287–298, 1995.
• [6] IDRISS, R.M., BOULANGER, R.W., “Soil Liquefaction During Earthquakes”, Report No. MNO-12, Earthquake Engineering Research Institute, California, USA, 2008.
• [7] ÇETİN, K., BİLGE, H., “Cyclic Large Strain and Induced Pore Pressure Models for Saturated Clean Sands” J. Geotech. Geoenviron. Eng., 138(3), 309–323, 2012.
• [8] POLITO, C.P., MARTIN, J.R., “The Effects of Nonplastic Fines on the Liquefaction Resistance of Sands”, J. Geotech. Geoenviron. Eng., 127, 408–415, 2008.
• [9] THEVANAYAGAM, S., “Effect of Fines and Confining Stress on Undrained Shear Strength of Silty Sands”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 124, 479–491, 1998.
• [10] AMINI, F., QI, G.Z., “Liquefaction Testing of Stratified Silty Sands”, Journal of Geotechnical and Geoenvironmental Engineering, 126, 208–217, 2000.
• [11] XENAKI, V.C., ATHANASOPOULOS, G.A., “Liquefaction Resistance of Sand-Silt Mixtures: An Experimental Investigation of the Effect of Fines”, Soil Dynamics and Earthquake Engineering, 23, 183–194, 2003.
• [12] HUANG, J., ZHANG, J., ZHANG, Z., XU, C.Y., WANG, B., YAO, J., “Estimation of Future Precipitation Change in the Yangtze River Basin by Using Statistical Downscaling Method”, Stochastic Environmental Research and Risk Assessment, 25, 781–792, 2011.
• [13] STAMATOPOULOS, C., “An Experimental Study of the Liquefaction Strength of Silty Sands In Terms Of the State Parameter”, Soil Dynamics and Earthquake Engineering, 30, 662–678, 2010.
• [14] EFRON, B., “Bootstrap Methods: Another Look at the Jackknife”, The Annals of Statistics, 1-26, 1979.
• [15] QUENOUILLE, M., “Approximation Tests of Correlation in Time Series”, Journal of the Royal Statistical Society, 11(1), 68-84, 1949.
• [16] EFRON, B., “Computers and the Theory of Statistics: Thinking the Unthinkable”, Siam Review, 21.4, 460-480, 1979.
• [17] EFRON, B., TIBSHIRANI, R., “Bootstrap Methods for Standard Errors, Confidence Intervals and Other Measures of Statistical Accuracy”, Stat. Sci. 1, 54-77, 1986.
• [18] EFRON, B., TIBSHIRANI, R.J., An Introduction to the Bootstrap, Chapman and Hall, Inc., New York, USA, 1993.
• [19] DAVISON, A.C., HINKLEY, D.V., Bootstrap Methods and Their Application (1th ed.), Cambridge Series in Statistical and Probabilistic Mathematics, Cambridge University Press, 1994.
• [20] TERCAN, A.E., “Global Rezerv Kestirimine İlişkin Güven Aralıklarının Uzaklık Bağımlı Bootstrap Yöntemi ile Belirlenmesi”, Madencilik, 41(3), 35-42, 2002.
• [21] KHAN, M.S., COULIBALY, P., DIBIKE, Y., “Uncertainty Analysis of Statistical Downscaling Methods”, Journal of Hydrology, 319, 357–382, 2006.
• [22] EFRON, B., Nonparametric Estimates of Standard Error: the Jacknife, the Bootstrap, and Other Resampling Methods”, Biometrika 68, 589-599, 1981.
• [23] EFRON, B., “The Jacknife, the Bootstrap and Other Resampling Plans”, SIANI Monograph No. 38. Philadelphia: Society for Industrial and Applied Mathematics, 1982.
• [24] HINKLEY, D.V., “Bootstrap Methods”, Journal of the Royal Statistical Society. Series B (Methodological), 321-337, 1988.
• [25] LEPAGE, R., BILLARD, L., Exploring the Limüs of Bootstrap, John Wiley & Sons, New York, USA 1992.
• [26] LAMBE, T.W., WHITMAN, R.V., Soil mechanics, Wiley, New York, USA 1969.
• [27] ASTM 4254-91, Standard Test Methods for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density.
• [28] ASTM 4253-93, Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table.
• [29] JGS0541-2000, Preparation of Soil Specimens for Triaxial Tests [30] JGS 0541-2000, Method for Cyclic Undrained Triaxial Test on Soils