Abstract
Helical anchors have been used to carry tension loads in different applications including transmission tower foundation, pipeline anchors, foundation repair elements, and excavation bracing. There have been numerous changes in the shape and size of helical anchors and piles since their first usage. Several researchers have studied their failure mechanism to find their pullout capacity. In this paper, the uplift capacity of helical screw anchors has been investigated through laboratory testing. Half-cut double-helix anchors were tested in a sand tank by varying helix size, helix spacing, and relative density of sand. A series of images were captured during the process of anchor pullout. The images were used to obtain displacement and strain fields by Particle Image Velocimetry (PIV). Load–displacement curves have been presented and compared to the earlier works. Afterwards, pullout capacity factors were calculated from peak load values. PIV analysis results were used to study the effects of helix spacing, helix size, and relative density of sand on the displacement fields. The results showed that the effect of helix spacing and soil density in increasing pullout load is more than that of helix size. Moreover, failure surfaces were discussed through displacement and strain fields. The findings indicated that failure surface above the top helix of deeply embedded anchors is a truncated cone with the angle of approximately \({\raise0.7ex\hbox{$\phi $} \!\mathord{\left/ {\vphantom {\emptyset 3}}\right.\kern-0pt}\!\lower0.7ex\hbox{$3$}}\), with the vertical and the failure surface shape between the two helices dependent on helix spacing.
Similar content being viewed by others
Abbreviations
- C :
-
Cohesion (kPa)
- \(\phi\) :
-
Angle of internal friction (°)
- \({C_{\text{u}}}\) :
-
Uniformity coefficient (–)
- \({C_{\text{c}}}\) :
-
Coefficient of curvature (–)
- \({D_{10}}\) :
-
Effective grain size (mm)
- \({\gamma}\) :
-
Unit weight (\({\raise0.7ex\hbox{${{\text{kN}}}$} \!\mathord{\left/ {\vphantom {{{\text{kN}}} {{{\text{m}}^3}}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${{{\text{m}}^3}}$}}\))
- \({\gamma _{\text{d}}}\) :
-
Dry unit weight (\({\raise0.7ex\hbox{${{\text{kN}}}$} \!\mathord{\left/ {\vphantom {{{\text{kN}}} {{{\text{m}}^3}}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${{{\text{m}}^3}}$}}\))
- H :
-
Embedment depth of top helix (mm)
- D :
-
Helix diameter (mm)
- A :
-
Area of the helices (mm2)
- s :
-
Helix spacing (mm)
- d :
-
Anchor rod diameter (mm)
- \({P_{\text{p}}}\) :
-
Peak pullout resistance (N)
- \({\delta _{\text{p}}}\) :
-
Anchor displacement at the moment of peak (mm)
- N :
-
Pullout capacity factor (–)
- \({D_{\text{r}}}\) :
-
Relative density (%)
- ROI:
-
Region of interest (–)
- \({\sigma _{{I_{\text{s}}}}}\) :
-
Standard deviation of the subset pixel intensities (–)
- SSSIG:
-
Sum of squares of subset pixel intensity gradients (–)
- \({n_{\text{s}}}\) :
-
Number of pixels in the subset (–)
- \({I_{i,j}}\) :
-
Intensity of the pixel in row i and column j of the subset (–)
- \(\bar {I}\) :
-
Mean subset pixel intensities (–)
- \({I^\prime }\) :
-
Intensity gradient (–)
- \({x_{{\text{re}}{{\text{f}}_i}}}\) :
-
x coordinate of an initial reference subset point (px)
- \({x_{{\text{re}}{{\text{f}}_c}}}\) :
-
x coordinate of the center of the initial reference subset (px)
- \({\tilde {x}_{{\text{cu}}{{\text{r}}_i}}}\) :
-
x coordinate of a current subset point (px)
- \({y_{{\text{re}}{{\text{f}}_j}}}\) :
-
y coordinate of an initial reference subset point (px)
- \({y_{{\text{re}}{{\text{f}}_c}}}\) :
-
y coordinate of the center of the initial reference subset (px)
- \({\tilde {y}_{{\text{cu}}{{\text{r}}_j}}}\) :
-
y coordinate of a current subset point (px)
References
Sharma M, Samanta M, Sarkar S (2017) Laboratory study on pullout capacity of helical soil nail in cohesionless soil. Can Geotech J 54(10):1482–1495
Mosallanezhad M, Moayedi H (2017) Developing hybrid artificial neural network model for predicting uplift resistance of screw piles. Arab J Geosci 10(22):479
Mitsch MP, Clemence SP (1985) The uplift capacity of helix anchors in sand. In: Uplift behavior of anchor foundations in soil, pp 26–47
MacDonald HF (1964) Uplift resistance of caisson piles in sand. Nova Scotia Technical College, Halifax
Bobbitt DE, Clemence SP (1987) Helical anchors: application and design criteria. In: Proceedings of the 9th Southeast Asian geotechnical conference, Bangkok, Thailand, vol 2, pp 6–105
Murray EJ, Geddes JD (1987) Uplift of anchor plates in sand. J Geotech Eng 113(3):202–215
Ghaly A, Hanna A, Hanna M (1991) Uplift behavior of screw anchors in sand. I: dry sand. J Geotech Eng 117(5):773–793
Ghaly A, Hanna A (1994) Model investigation of the performance of single anchors and groups of anchors. Can Geotech J 31(2):273–284
Ghaly A, Hanna A (1994) Ultimate pullout resistance of single vertical anchors. Can Geotech J 31(5):661–672
Ilamparuthi K, Dickin E, Muthukrisnaiah K (2002) Experimental investigation of the uplift behaviour of circular plate anchors embedded in sand. Can Geotech J 39(3):648–664
Nazir R, Chuan HS, Niroumand H, Kassim KA (2014) Performance of single vertical helical anchor embedded in dry sand. Measurement 49:42–51
Balla A (1961) The resistance to breaking-out of mushroom foundations for pylons. In: Proceedings of the 5th international conference on soil mechanics and foundation engineering, pp 569–576
Baker WH, Konder RL (1966) Pullout load capacity of a circular earth anchor buried in sand. Highway Res Rec 108
Matsuo M (1967) Study on the uplift resistance of footing (I). Soils Found 7(4):1–37
Matsuo M (1968) Study on the uplift resistance of footing (II). Soils Found 8(1):18–48
Meyerhof GG, Adams JI (1968) The ultimate uplift capacity of foundations. Cana Geotech J 5(4):225–244
Khadilkar BS, Paradkar AK, Golait YS (1971) Study of rupture surface and ultimate resistance of anchor foundations. In: Proceedings of 4th Asian regional conference on soil mechanics and foundation engineering, vol 1, pp 121–127
White DJ, Take WA, Bolton MD (2001) Measuring soil deformation in geotechnical models using digital images and PIV analysis. In: 10th international conference on computer methods and advances in geomechanics, vol 1, pp 997–1002
White DJ, Take Wa (2002) GeoPIV: particle image velocimetry (PIV) software for use in geotechnical testing. Cambridge University Department of Engineering, Cambridge
Niedostatkiewicz M, Lesniewska D, Tejchman J (2011) Experimental analysis of shear zone patterns in cohesionless for earth pressure problems using particle image velocimetry. Strain 47:218–231
Ahmadi H, Hajialilue-Bonab M (2012) Experimental and analytical investigations on bearing capacity of strip footing in reinforced sand backfills and flexible retaining wall. Acta Geotech 7(4):357–373
Jahanandish M, Ansaripour M (2016) Application of particle image velocimetry in establishing the field of zero extension lines in soils. Iran J Sci Technol Trans Civ Eng 4(40):337–348
Liu J, Liu M, Zhu Z (2012) Sand deformation around an uplift plate anchor. J Geotech Geoenviron Eng 138(6):728–737
Raee E, Hataf N, Barkhordari K, Ghahramani A (2018) The effect of rigidity of reinforced stone columns on bearing capacity of strip footings on the stabilized slopes. Int J Civ Eng 1–13
Blaber J, Adair B, Antoniou A (2015) Ncorr: open-source 2D digital image correlation matlab software. Exp Mech 55(6):1105–1122
Stanier SA, White DJ (2013) Improved image-based deformation measurement in the centrifuge environment. Geotech Test J 36(6):2013
Ghaly A, Hanna A (1992) Stresses and strains around helical screw anchors in sand. Soils Found 32(4):27–42
Perko HA (2009) Helical piles: a practical guide to design and installation. Wiley, New York
Stanier S, Dijkstra J, Leśniewska D, Hambleton J, White D, Wood DM (2016) Vermiculate artefacts in image analysis of granular materials. Comput Geotech 72:100–113
Pan B, Xie H, Wang Z, Qian K, Wang Z (2008) Study on subset size selection in digital image correlation for speckle patterns. Opt Exp 16(10):7037–7048
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Motamedinia, H., Hataf, N. & Habibagahi, G. A Study on Failure Surface of Helical Anchors in Sand by PIV/DIC Technique. Int J Civ Eng 17, 1813–1827 (2019). https://doi.org/10.1007/s40999-018-0380-2
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s40999-018-0380-2