Effects of installation disturbance on behavior of multi-helix piles in structured clays

Helical piles and anchors are installed by applying torque to the pile head. Their application as a foundation option has gained popularity in recent years because of their intrinsic advantages of rapid installation with minimal vibration and noise, and the development of powerful hydraulic driving heads. In spite of extensive research that investigated the behavior of helical piles and anchors, discrepancies between predictions and actual observations of axial behavior of helical piles installed in clay still exist. This is, in large part, because much of previous research involved installation of helical pile models in remolded (reconstituted) cohesive materials rather than natural soil deposits. Since the strength of the remolded materials does not change significantly, the effects of installation cannot be distinguished in remolded materials. In this study, full scale uplift and compression load tests data are analyzed and different failure patterns have been investigated for helical piles and anchors installed in structured clays. The research findings indicate that the behavior of the helical piles and anchors is significantly affected by the degree of soil disturbance induced by penetration of pile shaft and helices. In addition, back-calculated undrained shear strength mobilized by different sections of pile revealed that, for helical piles and anchors installed in structured clay, the undrained shear strength should be reduced to account for installation disturbance.

[1]  C. P. Wroth,et al.  An analytical solution for the consolidation around a driven pile , 1979 .

[2]  Samuel P. Clemence,et al.  UPLIFT CAPACITY OF HELICAL ANCHORS IN CLAY AND SILT. , 1985 .

[3]  M. Randolph,et al.  Stress and pore pressure changes in clay during and after the expansion of a cylindrical cavity , 1979 .

[4]  G. G. Meyerhof,et al.  The Behavior of Piles Driven in Clay. I. An Investigation of Soil Stress and Pore Water Pressure as Related to Soil Properties , 1972 .

[5]  Jonathan D. Bray,et al.  Effect of Pile Driving on Static and Dynamic Properties of Soft Clay , 2002 .

[6]  P. R. Vaughan,et al.  The general and congruent effects of structure in natural soils and weak rocks , 1990 .

[7]  S. N. Rao,et al.  Lateral Capacity of Helical Piles in Clays , 1996 .

[8]  Yasunori Koizumi,et al.  Field Tests with Regard to Pile Driving and Bearing Capacity of Piled Foundations , 1967 .

[9]  J Biarez,et al.  BEARING CAPACITY AND SETTLEMENT OF PILE FOUNDATIONS , 1977 .

[10]  Jessica Young.  Uplift capacity and displacement of helical anchors in cohesive soil , 2012 .

[11]  Kenichi Soga,et al.  Fundamentals of Soil Behaviour , 2005 .

[12]  H. Bolton Seed,et al.  Closure of "The Action of Soft Clay along Friction Piles" , 1957 .

[13]  Diane Jia Ying. Zhang,et al.  Predicting capacity of helical screw piles in Alberta soils , 1999 .

[14]  M. Roy,et al.  Long-term behaviour of reconsolidated clay around a driven pile , 1986 .

[15]  Chris M. Martin,et al.  Applications of the lower and upper bound theorems of plasticity to collapse of circular foundations , 2001 .

[16]  S. N. Rao,et al.  THE BEHAVIOUR OF MODEL SCREW PILES IN COHESIVE SOILS , 1991 .

[17]  Serge Leroueil,et al.  BEHAVIOR OF DESTRUCTURED NATURAL CLAYS , 1979 .

[18]  G G Mayerhof,et al.  Bearing Capacity and Settlement of Pile Foundations , 1976 .

[19]  K Y Lo,et al.  INDUCED PORE PRESSURES DURING PILE-DRIVING OPERATIONS , 1965 .

[20]  Armin W. Stuedlein,et al.  Uplift Performance of Multi-Helix Anchors in Desiccated Clay , 2012 .

[21]  Kaare Flaate.  Effects of Pile Driving in Clays , 1972 .

[22]  R. S. Merifield,et al.  Ultimate Uplift Capacity of Multiplate Helical Type Anchors in Clay , 2011 .

[23]  Y. V. S. N. Prasad,et al.  Estimation of Uplift Capacity of Helical Anchors in Clays , 1993 .

[24]  M. Hesham El Naggar,et al.  Axial compressive capacity of helical piles from field tests and numerical study , 2013 .

[25]  J. Burland.  On the compressibility and shear strength of natural clays , 1990 .

[26]  Armin W. Stuedlein,et al.  Displacement of Spread Footings on Aggregate Pier Reinforced Clay , 2008 .

[27]  Alan J. Lutenegger.  Behavior of Grouted Shaft Helical Anchors in Clay , 2011 .

[28]  Alan J. Lutenegger,et al.  Cylindrical Shear or Plate Bearing? — Uplift Behavior of Multi-Helix Screw Anchors in Clay , 2009 .

[29]  M. Sakr.  Installation and Performance Characteristics of High Capacity Helical Piles in Cohesive Soils , 2012 .

[30]  El NaggarM. Hesham,et al.  Axial compressive response of large-capacity helical and driven steel piles in cohesive soil , 2015 .