مطالعه آزمایشگاهی اثر بارگذاری در حالت رفت و برگشت بر شمع های پیچشی پره ای درمدل فیزیکی FCV

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشجوی دکتری ژئوتکنیک، گروه مهندسی عمران، واحد علوم و تحقیقات، دانشگاه آزاد اسلامی، تهران، ایران

2 استاد، دانشکده مهندسی عمران و محیط زیست، دانشگاه صنعتی امیرکبیر، تهران، ایران

3 استادیار، گروه مهندسی عمران، واحد علوم و تحقیقات، دانشگاه آزاد اسلامی، تهران، ایران

10.22065/jsce.2021.247246.2232

چکیده

استفاده از شمع‌های پیچشی پره‌ای در سالهای اخیر در فونداسیون سازه‌های دریایی که درمعرض امواج رفت و برگشتی آب دریا قرار دارند، رواج زیادی پیدا نموده است. از طرفی به دلیل زمان اندک مورد نیاز برای نصب در زمین و قابلیت بارگذاری بلافاصله بعد از نصب، سرعت احداث فونداسیون و نصب و تسریع در برپایی سازه اصلی مورد توجه خاص قرار گرفته است. در تحقیق حاضر به منظور بررسی رفتارشمع‌های پیچشی پره‌‌ای تحت بارگذاری کششی و فشاری‌، سه تیپ شمع پیچشی بصورت تک پره ، دو پره و سه پره، با اقطار 70 و 90 میلیمتر و نسبت فاصله بین پره‌ها به قطر آنها در اندازه‌های 5/1 و 3 تحت آزمایش قرار گرفتند. خاک مورد آزمایش ماسه بندر انزلی بوده و با اعمال رطوبت 4 درصد ، در تراکم‌های سست و متوسط ارزیابی‌ها صورت گرفتند. فشار کف اعمال شده در دستگاه فشار همه جانبه مخروطی دانشگاه صنعتی امیرکبیر (FCV-AUT) برابر با 200 کیلوپاسکال بوده است. نتایج نشان داد که اینگونه شمع‌ها در بارگذاری فشاری و کششی رفتار مناسبی داشته و در اثر بهسازی و افزایش تراکم خاک‌، ظرفیت باربری بطور قابل ملاحظه‌ای افزایش یافت. ولیکن رفتار شمع‌های پیچشی پره‌ای در اثر توالی بارگذاری فشاری و کششی، رفتار کاهشی داشته است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Laboratory Study of the Helical Piles Behavior Under Reciprocal Loading Via Frustum Confining Vessel (AUT-FCV)

نویسندگان [English]

  • Hossein Safikhani 1
  • Abolfazl Eslami 2
  • Navid Ganjian 3
  • Amin Bahmanpour 3
1 PhD Student in Geotechnics, Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 Professor, Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran
3 Assistant Professor, Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
چکیده [English]

Pile foundations are one of the significant marine substructure systems for a variety of offshore and onshore facilities. In recent years, helical piles have become common foundation system for marine structures exposed to the reciprocal seawater waves. Moreover, these foundation systems have received particular attention due to several influential parameters, including the limited required time for installing and the ability to be immediately loaded after installation. However, the methods for estimating their bearing capacity is limited. The present study investigates the behavior of three different helical piles under tensile and compressive loading via Frustum Confining Vessel available at Amirkabir University of Technology (FCV-AUT). The under-study piles were single, double, and triple-helix with diameters of 70 and 90 mm. Double and triple-helix piles are designed with two different spacing to helix diameter ratios of 1.5 and 3. These piles were installed in Bandar Anzali sand regarding two loose and medium densities. The soil was prepared by adding 4% humidity for testing. The applied bottom pressure of FCV-AUT was 200 kPa. The results indicated that the helical pile bearing capacity increased due to soil improvement and densification during the special installation procedure. However, during the reciprocal loading, the tensile capacity of helical piles was reduced.

کلیدواژه‌ها [English]

  • Helical Piles
  • FCV physical modeling
  • Bearing Capacity
  • tension loading
  • compression loading
  • reciprocal loading
[1] Perko, H. (2009). A practical guide to design and installation. John Wiley & Sons Inc, Hoboken. NJ. USA.
[2] Di Bernardo, G. (2012). Helical pile deck foundation.New jersey deck boulder. USA.
[3]Trofimenkov, J.G. and Maruipolshii, L.G. (1965). Screw piles used formats and foundations.In: Proceedings of the 6th      International Conferenceon Soil Mechanics and Foundation Engineering. vol.2, pp.328–332.
[4] Adams, J.I. and Klym, T.W. (1972). A study of anchors for transmission tower foundations.Canadian Geotechnical Journal, 9(1), 89–104.
[5] Vickers, R. and  Clemence, S.P. (2000). Performance of helical piles with grouted shafts. New Technological and Design Developments in Deep Foundations. American Society of Civil Engineers. USA. pp.327–341.
[6] Nasr, M.H. (2004). Large capacity screw piles.In: Proceedings oft he International Conference .Future Vision and Challenges for Urban Development. Cairo, Egypt,20–22 December, pp.1–15.
[7] Sakr , M. (2010). High capacity helical piles;  a new dimension for bridge foundations.In: Proceedings of 8th International Conference on Short and Medium Span Bridges, Niagara Falls, Canada, 2010.
[8] Merifield, R. S. (2011). Ultimate uplift capacity of multiplate helical type anchors in clay. Journal of Geotechnical and Geoenviromental Engineering, ASCE, pp 704-712.
[9] Zhang, D.J.Y. (1999). ”Predicting capacity of helical screw piles in Alberta soils”. MSc Thesis, Geotechnical Engineering, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alta.
[10] Rawat, S. and Gupta, A.K. (2017). Numerical modelling of pullout of helical soil nail. Journal of Rock Mechanics and Geotechnical Engineering 9 (2017) 648e658.
[11] Abranj, A. (2013). Investigating the effects of run on deep PC performance using a pressure device
conical immersive (FCV)
. MSc in Civil Engineering. Amirkabir University of Technology.
[12] Horvath, R.G. (1996). Frustum for testing model piles. Canadian Geotechnical Journal, Vol. 33, No.3, June, pp. 499-504.
[13] Khazaei, J. (2016). Study of helical piles behavior via frustum confining vessel. PhD Thesis. Amirkabir University of Technology.
[14] Sedran, G. (1999). Experimental and analytical study of a frustum confining vessel, Doctoral Thesis, McMaster University.
 [15] Zare, M. and Eslami, A. (2014). Study of deep foundations performance by frustum confining vessel (FCV). PhD Thesis. Amirkabir University of Technology.
[16] CFEM, (2006). Canadian foundation engineering manual, Canadian Geotechnical Society, Technical Members of Foundations, BiTech Publishers Ltd., Richmond, EC.
 [17] Beigi.F. (2018). Comparison of the behavior of various candle models in a comprehensive pressure device cone, University of Amirkabir (FCV-AUT). MSc in Civil Engineering. Amirkabir University of Technology.
[18] Zarrabi, M. and Eslami, A. (2016). Behavior of piles under different installation effects by physical modeling. Int. J. Geomech., 04016014.ASCE.
[19] Nabizadeh,F.(2016). Laboratory study and performance accuracy of screw piles in sandy soils. Journal of Structural and Construction Engineering (JSCE).Vol.3,No.3,pp.5-15