Comprehensive Analysis of Screw Piles: Design, and Applications

This presentation provides a detailed analysis of axially loaded screw piles, beginning with background information, an introduction to screw piles, and their historical context. It explores methods for designing screw piles, including bearing capacity, the cylindrical shear model, and axial capacity methods, focusing on vertically loaded piles in both cohesionless and cohesive soils. The presentation highlights the advantages of screw piles, such as ease of installation and reusability, while also addressing disadvantages like soil condition limitations. It discusses the installation process and its impact on design, emphasizing the importance of torque and downward pressure. The presentation concludes by examining the determination of bearing capabilities, differentiating between cohesionless and cohesive soil analysis, and providing formulas for calculating uplift capacity, referencing key sources in the bibliography.

Presentation on
Screw Piles
This presentation is focuses on the analysis of screw piles analysis is the
background information of the crew piles, then the introduction of the
screw piles and then the historical perspectives of the screw piles and
their implications. The methods of designing screw piles include bearing
capacity, cylindrical shear model, and axial capacity methods. The axial
piles that are vertically loaded in tension and compression in both
cohesionless soils and cohesion form the primary of the analysis of the
screw piles.

Figure 1: Screw Pile Elements

Advantages and Disadvantages of Screw Piles
The disadvantages and advantages of crew piles are critical in the
determination of the conditions under which they are most suitable and
important compared to other customary methods of piling. Some of the
advantages of crew piles include ease in installation, reusability,
removability, suitable for regions with restricted access, and quick
installation where loaded can follow soon. Despite the advantages
above, the screw piles are faced with numerous disadvantages such as
the assertion of disadvantageous conditions of the soil for the screw
piles like boulders, bedrocks, and rocky soils. However, these
drawbacks can be mitigated by the use of surface with a sharp toe when
rocks that are weak are met to improve the rock passage.

The process of installation of the crew piles is understood to have an
effect of the design. The normal procedure entails advancing the
screw piles into the soil through the use of motor of hydraulic
torque which consequences in the penetration of the helices in the
soil through rotations by the application of a moment of turning at
the head of the shaft. When the pitch of every helix is similar, this
enables further installations since every succeeding helix follows the
similar trail as the one previously. The installation of crew piles
entails torque application and also the downward pressure
application which is commonly known as the crowd.

Determination of Bearing Capabilities
The common properties and parameters utilized in
the determination of the bearing capabilities include
:

The primary difference in the analysis of cohesionless and cohesive soils under loads
of compression is the utilization of the angle of internal friction which is utilized in the
analysis of cohesion as shown below:
Thus: The capacity of the uplift can be calculated by:
Nu=1.2H1/Dis equals to or less than 9, where H1 is the uppermost helix’s depth and in
the cohesion less soil, the Nq value is factor of dimensionless and varies according to
the angle of the internal friction of the soil.

Conclusion
This research paper focuses on the analysis of
axially loaded screw piles. The first section of
screw piles analysis is the background
information of the crew piles, then the
introduction of the screw piles and then the
historical perspectives of the screw piles and
their implications.

Bibliography
• Tomlinson M, 2015. Foundation Design and Construction. Malaysia: Pearson Prentice Hall.
• Trofimenkov J, 2011. Screw piles used for mast and tower foundations. Toledo:
Proceedings of the 6th International Conference on Soil Mechanics and Foundation
Engineering.
• Vickars H, 2016. Performance of helical piles with grouted shafts. Paris: Geotechnical
Special Publication.
• Vickars R, 2013. Performance of helical piles with grouted shafts. New York: New
Technological and Design Developments in Deep Foundations, American Society of Civil
Engineers.
• Vito D, 2012. Highly loaded helical piles in compression and tension applications: a case
study of two projects. Colorado: Proceedings of the Pan-Am CGS Geotechnical
Conference.