Abstract




 
   

IJE TRANSACTIONS B: Applications Vol. 28, No. 2 (February 2015) 180-189   

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  FRICTIONAL STRAIN HARDENING-SOFTENING IN EXPERIMENTAL AND NUMERICAL INVESTIGATION OF ARCHING EFFECT
 
G Moradi and A. R. Abbasnejad
 
( Received: May 09, 2014 – Accepted: November 13, 2014 )
 
 

Abstract    In the current paper the results of a numerical simulation that were verified by a well instrumented experimental procedure for studying the arching effect over a trapdoor in sand is presented. To simulate this phenomenon with continuum mechanics, the experimental procedure is modeled in ABAQUS code using stress dependent hardening in elastic state and plastic strain dependent frictional hardening-softening with Mohr Coulomb failure criterion applying user sub-routine. The apparatus comprises concentric circular trapdoors with different diameters that can yield downward while stresses and deformations are recorded simultaneously. As the trapdoor starts to yield, the whole soil mass deforms elastically. However, after an immediate specified displacement, depending on the diameter of the trapdoor, the soil mass behaves plastically. This behavior of sand occurs due to the flow phenomenon and continues until the stress on trapdoor is minimized. Then the failure process develops in sand and the measured stress on the trapdoor shows an ascending trend. This indicates gradual separation of the yielding mass from the whole soil body. Finally, the flow process leads to establish a stable vault of sand called arching mechanism or progressive collapse of the soil body.

 

Keywords    Arching effect, Modified Mohr Coulomb, Frictional hardening-softening, ABAQUS.

 

چکیده    در این مقاله نتایج شبیه سازی عددی با نتایج حاصل از مدل آزمایشگاهی جهت بررسی پدیده قوس در ماسه ارائه شده است. روش آزمایشگاهی دقیقاً در نرم افزار ABAQUS مدل سازی گردیده و از رفتار سخت شدگی وابسته به تنش در قسمت الاستیک و همچنین سخت شدگی و نرم شدگی وابسته به کرنش پلاستیک همراه با معیار گیسختگی موهر- کولمب استفاده شده است. این رفتار توسط زیربرنامه دیگری در نرم افزار تعریف گردید. در مدل فیزیکی از دریچه های دایروی با اقطار مختلف و با قابلیت حرکت به سمت پایین همراه با ابزاربندی جهت قرائت تنش ها و جابجایی ها بهره گرفته شده است. زمانی که دريچه شروع به پايين آمدن می‌کند،توده خاک بالای دريچه در محدوده الاستيک جابه‌جا می‌شود. سپس، بعد از يک جابه‌جايي مشخص، که مقدار آن بستگی به قطر دريچه و دانسيته نسبی ماسه دارد، توده رفتار پلاستيک از خود نشان می‌دهد. اين رفتار ماسه، که بدليل بروز پديده جريان به وقوع می‌پيوندد، تا آنجا که تنش روی دريچه کمترين شود، ادامه می‌يابد، تا اين که گسيختگی در توده به وقوع می‌پيوندد و تنش اندازه‌گيری شده روی دريچه به سمت يک مقدار معين ميل می‌کند. اين مرحله جدا شدگی قسمتی از توده از ماسه مجاور می‌باشد و یا گسیختگی پیش رونده تا سطح ماسه ادامه پیدا می کند که منجر به افزایش تنش اعمال شده به دریچه می شود.

References   

 

1.     Terzaghi, K., "Theoretical soil mechanics", (1943).

2.     Finn, W., "Boundary value problems of soil mechanics", Journal of Soil Mechanics and Foundation Division, ASCE,  Vol. 89, (1963), 39-72.

3.     Getzler, Z., Komornik, A. and Mazurik, A., "Model study on arching above buried structures", Journal of Soil Mechanics & Foundations Div, (1968).

4.     Ladanyi, B. and Hoyaux, B., "A study of the trap-door problem in a granular mass", Canadian Geotechnical Journal,  Vol. 6, No. 1, (1969), 1-14.

5.     Burghignoli, A., "Soil interactin in buried structures", Source: Proceeding of the International Conference on Soil, (Univ of Rome, Italy),  Vol. 2, (1981), 69-74.

6.     Vardoulakis, I., Graf, B. and Gudehus, G., "Trapdoor problem with dry sand: A statical approach based upon model test kinematics", International Journal for Numerical and Analytical Methods in Geomechanics,  Vol. 5, No. 1, (1981), 57-78.

7.     Chevalier, B. and Otani, J., "3-d arching effect in the trap-door problem: A comparison between X-Ray ct scanning and DEM analysis", in GeoFlorida 2010@ sAdvances in Analysis, Modeling & Design, ASCE, (2010), 570-579.

8.     Sadrekarimi, J. and Abbasnejad, A., "Arching effect in fine sand due to base yielding", Canadian Geotechnical Journal,  Vol. 47, No. 3, (2010), 366-374.

9.     Hosseinian, S. and Seifabad, M.C., "Optimization the distance between piles in supporting structure using soil arching effect", Optimization,  Vol. 3, No. 6, (2013), 386-391.

10.   Dalvi, R.S. and Pise, P.J., "Analysis of arching in soil-passive state", Indian Geotechnical Journal,  Vol. 42, No. 2, (2012), 106-112.

11.   Maynar, M.J. and Rodríguez, L.E., "Discrete numerical model for analysis of earth pressure balance tunnel excavation", Journal of Geotechnical and Geoenvironmental Engineering,  Vol. 131, No. 10, (2005), 1234-1242.

 12.   Vardakos, S.S., Gutierrez, M.S. and Barton, N.R., "Back-analysis of shimizu tunnel No. 3 by distinct element modeling", Tunnelling and Underground Space Technology,  Vol. 22, No. 4, (2007), 401-413.

13.   Chen, R., Tang, L., Ling, D. and Chen, Y., "Face stability analysis of shallow shield tunnels in dry sandy ground using the discrete element method", Computers and Geotechnics,  Vol. 38, No. 2, (2011), 187-195.

14.   Dang, H.K. and Meguid, M.A., "An efficient finite–discrete element method for quasistatic nonlinear soil–structure interaction problems", International Journal for Numerical and Analytical Methods in Geomechanics,  Vol. 37, No. 2, (2013), 130-149.

15.   Sadrekarimi, J. and Abbasnejad, A., "An experimental investigation into the arching effect in fine sand", International Journal of Engineering-Transactions B: Applications,  Vol. 21, No. 4, (2008), 345-360..

16.   Sardrekarimi, J., Moradi, G. and Abbasnejad, A.R., "Studying and comparing the experimental and numerical investigation on to the arching effect in fine sand using plaxis code and mohr-coulomb criteria", Proceeding of 4th International conference on geotechnical engineering, Tehran, Iran, (2010).

17.   Atkinson, J. and Potts, D., "Stability of a shallow circular tunnel in cohesionless soil", Geotechnique,  Vol. 27, No. 2, (1977), 203-215.

18.   ABAQUS, " Inc. Abaqus v.6.12.1 user’s manual", (2012).

19.   Wroth, C., "Correlations of some engineering properties of soils", in Proceedings of the Second International Conference on the Behaviour of Off-Shore Structures, held at Imperial College, London, England. Vol., No. Issue, (1979).

20.   Wroth, C., "Soil mechanics-property characterization and analysis procedures", Proceedings of the 11th International Conference on Soil Mechanics and Foundation Engineering, San Francisco, Vol. 1, (1985), 1-55.

21.   Vermeer, P.A. and De Borst, R., "Non-associated plasticity for soils, concrete and rock",  (1984).

22.   Rowe, P., "Stress-dilatancy, earth pressures, and slopes", ASCE, JSMFE,  Vol. 89, (1963), 37-62.

23.   Soreide, O., Nordal, S., Bonnier, P. and Mestat, P., "An implicit friction hardening model for soil materials", in Proc. 5th Europ. Conf. on Numerical Methods in Geotechnical Engng (NUMGE), Mestat (ed.), Paris, France. Presses de l’ENPC/LCPC, (2002), 155-161.

24.   Shibuya, S., Mitachi, T. and Tamate, S., "Interpretation of direct shear box testing of sands as quasi-simple shear", Geotechnique,  Vol. 47, No. 4, (1997), 769-790.

25.   Vardoulakis, I. and Graf, B., "Calibration of constitutive models for granular materials using data from biaxial experiments", Geotechnique,  Vol. 35, No. 3, (1985), 299-317.

26.   Jewell, R. and Wroth, C., "Direct shear tests on reinforced sand", Geotechnique,  Vol. 37, No. 1, (1987), 53-68.

27.   Chevalier, B., Combe, G. and Villard, P., "Experimental and numerical studies of load transfers and arching effect", The 12th International Conference of International Association for Computer Methods and Advances in Geomechanics (IACMAG), Goa, India, Citeseer, (2008), 273-280.

 





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