پیوندهای مفید
آمار
| تعداد نشریات | 8 |
| تعداد شمارهها | 444 |
| تعداد مقالات | 5,694 |
| تعداد مشاهده مقاله | 7,895,405 |
| تعداد دریافت فایل اصل مقاله | 6,443,255 |
اثر ریزدانهها بر کرنش برشی آستانه ماسه های اشباع | ||
| نشریه مهندسی عمران امیرکبیر | ||
| مقاله 11، دوره 47، شماره 1، شهریور 1394، صفحه 131-140 اصل مقاله (867.58 K) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22060/ceej.2015.478 | ||
| نویسندگان | ||
| سید مجدالدین میر محمد حسینی* 1؛ مهدی درخشندی2 | ||
| 1استاد، دانشکده مهندسی عمران و محیط زیست، دانشگاه صنعتی امیرکبیر، تهران، ایران | ||
| 2استادیار، دانشکده مهندسی عمران، دانشگاه آزاد اسلامی واحد علوم و تحقیقات، تهران، ایران | ||
| چکیده | ||
| یکی از خصوصیات مهم ماسههای اشباع تحت بارهای سیکلی کرنش برشی آستانه ( ) میباشد. کرنش برشی آستانه بمنظور بررسی فشار منفذی ایجاد شده ناشی از بارهای زلزله، ماشین آلات ارتعاشی وکلیه بارهای سیکلی موقت یا همیشگی وارده بر خاک تعیین میشود. بر اساس مطالعات انجام شده کرنش برشی آستانه میزان کرنشی است که تا قبل از آن فشار آب حفرهای در حالت اشباع و نوسانات حجمی در حالت خشک دستخوش تغییر نشوند. با افزایش مقدار کرنش برشی به بیش از تغییرات در فشار منفذی معنیدار شده و ریز ساختار خاک دستخوش تغییر میشود. در این تحقیق نمونههایی از ماسههای حاوی ریزدانههای چسبنده و غیر چسبنده با استفاده از روش تراکم کاهش یافته مرطوب تهیه شده و با انجام آزمایشهای سه محوری سیکلی کنترل کرنش در محدوده کرنشهای کوچک، اثر نوع و مقدار ریزدانهها بر کرنش برشی آستانه این خاکها مورد بررسی قرار گرفته است. نتایج آزمایشها نشان میدهند با افزایش مقدار ریزدانههای چسبنده به بیش از 20 درصد، کرنش برشی آستانه نیز به میزان قابل توجهی نسبت به ماسه تمیز افزایش مییابد. همچنین افزایش ریزدانههای غیر چسبنده، ابتدا افزایش و سپس کاهش کرنش برشی آستانه را نشان میدهد. | ||
| کلیدواژهها | ||
| کرنش برشی آستانه؛ ماسههای اشباع؛ ریزدانههای چسبنده و غیر چسبنده؛ فشار آب منفذی؛ آزمایش سه محوری سیکلی کنترل کرنش | ||
| عنوان مقاله [English] | ||
| The Effect of Fines on Threshold Shear Strain of Saturated Sands | ||
| نویسندگان [English] | ||
| Seyed magdldin Mir Mohammad Hosseini1؛ Mehdi Derakhshandi2 | ||
| 1Professor, Department of Civil & Environmental Engineering, Amirkabir University of Technology, Tehran, Iran. | ||
| 2Assistant professor, Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran | ||
| چکیده [English] | ||
| Threshold shear strain is one of the basic parameters of soil during cyclic loading condition. The threshold shear strain should be determined for evaluating pore water pressure generation due to earthquake, vibrating machine and all the cyclic loading which apply permanently or temporary on the soil. According to many scientific researches, the threshold shear strain is the strain, which there is no pore water pressure generation at the saturated soils and no volume changes at the dry conditions during cyclic loading. By increasing the shear strain more than threshold shear strain ( ), pore pressure increase is noticeable at the saturated soil and the soil microstructure starts to change. In this study, the effects of plastic and non-plastic fines on the threshold shear strain of saturated sands were evaluated by performing a number of cyclic triaxial tests with strain control method at small shear strain. All the specimens contained 0%, 10%, 20% and 30% plastic and non-plastic fines prepared by wet tamping undercompaction method. As a result, by increasing plastic fines more than 20%, threshold shear strain increased significantly. Moreover, by increasing non-plastic fines, threshold shear strain fluctuated. It first increased and then decreased. | ||
| کلیدواژهها [English] | ||
| Threshold Shear Strain, Saturated Sands, Plastic and Non-plastic Fines, Pore Pressure, Strain-controlled Cyclic Triaxial Test | ||
|
سایر فایل های مرتبط با مقاله
|
||
| مراجع | ||
|
[1] Drenvich, V.P., Richart, F.E. JR., “Dynamic prestraining of dry sand”, Journal of Soil Mechanics and Foundation Engineering Division (ASCE), Vol. 96, No. 2, pp. 453- 469, 1970. [2] Anderson, D.G., Richart F.E., JR., “Effects of straining on shear modulus of clays”, Journal of Geotechnical Engineering Division (ASCE),Vol.102, No. 9, pp. 975- 987, 1976. [3] Dobry, R., Ladd R., “Discussion of Soil liquefaction and cyclic mobility evaluation for level ground during earthquakes by Seed HB and Liquefaction potential: science versus practice by Peck RB”, Journal of Geotechnical Engineering Division (ASCE), Vol. 106, No. 6, pp. 720- 724,1980. [4] Dobry, R., Ladd, R.S., Yokel, F.Y., Chung, R.M., and Powell, D., “Prediction of pore water pressure buildup and liquefaction of sands during earthquakes by the cyclic strain method”,National Bureau of Standards Building. Sci. Series 138, Washington, D.C., 1982. [5] Ladd, R. S., Dobry, R., Dutko, P., Yokel, F. Y., and Chung, R.M., ‘‘Pore-water pressure buildup in clean sands because of cyclic straining’’, Geotechnical Testing Journal, Vol. 12, Issue.1,pp. 77– 86, 1989. [6] Stoll R.D., Kald, L., “Threshold of dilation under cyclic loading”, Journal of Geotechnical Engineering Division, ASCE, Vol. 103, No. 10,pp. 1174- 1178, 1977. [7] Ishihara K., “Strength of cohesive soils under transient and cyclic loading conditions”, State-of-the-Art in Earthquake Engineering, Proceeding, 7th World Conference on Earthquake Engineering, Istanbul, Turkey, pp. 154- 169, 1981. [8] Vucetic, M., “Cyclic threshold shear strains in soil”, Journal of Geotechnical Engineering, ASCE, Vol.120, No. 12, pp. 2208– 2228, 1994. [9] Hsu, C.C., Vucetic, M., “Threshold shear strain for cyclic pore water pressure in cohesive soils”, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 32, No.10, pp. 1325- 1335, 2006. [10] Hazirbaba, K., Rathje, E.M., “Pore pressure generation of silty sands due to induced cyclic shear strains”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 135, No. 12, pp. 1892- 1905, 2009. [11] Tabata, K., Vucetic, M., “Threshold shear strain for cyclic degradation of three clays”, Proceedings of the 5th International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, On CD-ROM, Session 1a, Paper No. 1.15a, San Diego, California, Publisher: Missouri University of Science and Technology, 12 pages, 2010. [12] Mortezaie, A., and Vucetic, M., “Small-strain cyclic testing with standard NGI simple shear device”, Geotechnical Testing Journal (ASTM), Vol. 45, Issue. 6, pp. 935- 948, 2012. [13] Ladd, R.S., “Preparing test specimens using undercompcation”, Geotechnical Testing Journal, Vol.1, No. 1, pp. 16- 23, 1978. [14] Erten, D., “Effect of fines content on liquefaction potential of sands”, Ph.D. Dissertation, Rutgers the State University of New Jersey– New Brunswick, U.M.I., 1994. [15] Finn, W.D.L., Pickering, D.J. and Bransby, P.L.,“Sand liquefaction in triaxial and simple shear tests”, Journal of the Soil Mechanics and Foundations Division, ASCE, Vol. 97, No. SM4, pp. 639- 659, 1971. [16] Boulanger, R.W., Seed, R.B., Chan, C.K., Seed, H.B., Sousa J., “Liquefaction behavior of saturated sands under uni-directional and bi-directional monotonic and cyclic simple shear loading”, Report No. UCB/GT/91- 08, University of California, Berkeley, 1991. [17] Polito, C.P., “The effects of non-plastic and plastic fines on the liquefaction of sandy soils”, Ph.D. Dissertation, Virginia Polytechnic Institute and State University, 1999. [18] ASTM D854, “Standard test methods for specific gravity of soil solids by water pycnometer”, 2000. [19] ASTM D4318-05, “Standard test methods for liquid limit, plastic limit, and plasticity index of soils”, 2000. [20] ASTM D 4253, “Standard test methods for maximum index density and unit weight of soils using a vibratory table”, 2000. [21] ASTM D 4254, “Standard test methods for minimum index density and unit weight of and calculation of relative density”, 2000. [22] ASTM D 1557, “Standard test methods for laboratory compaction characteristics of soil using modified effort”, 2000. [23] Youd, T.L., “Compaction of sands by repeated shear straining”, Journal of Soil Mechanics and Foundations Division (ASCE), Vol. 98, No. SM, pp. 709- 725, 1972. [24] Pitman, T.D., Robertson, P.K., and Sego D.C., “Influence of fines on the collapse of loose sands”, Canadian Geotechnical Journal, Vol. 31, No. 5, pp. 728– 739, 1994. [25 Derakhshandi M., Rathje EM., Hazirbaba K., and Mirhosseini, S.M., “The effect of plastic fines on pore pressure generation characteristics in saturated sands”, Soil Dynamics and Earthquake Engineering, Vol. 28, No. 5, pp. 376- 386, 2008. | ||
|
آمار تعداد مشاهده مقاله: 2,084 تعداد دریافت فایل اصل مقاله: 1,661 |
||
