Among all foundation types, screw pile foundations are considered one of the easiest to install. Despite their simplicity, they effectively solve many construction problems associated with suboptimal soil conditions or uneven terrain.
Installing a screw pile foundation doesn't require much time
or effort, and in most cases, it delivers the expected results. However, even
such a simple technology can have its pitfalls. Mistakes made during screw pile
installation can have serious consequences for both the foundation and the
entire structure.
Because of the relative simplicity of the installation
technology, many people attempt to assemble screw pile foundations themselves,
which often leads to unpleasant consequences.
In this article, we'll look at five common mistakes
inexperienced installers make when installing screw pile foundations. Be
careful and avoid them!
Soil analysis is not
performed.
Neglecting a thorough soil survey is a serious mistake when
constructing a screw pile foundation. Even though this type of foundation is
claimed to be suitable for any type of soil, a thorough soil survey is
essential for successful construction.
Skimping on a thorough soil survey can lead to serious
consequences, including instability and damage to the foundation structure. A
high-quality soil analysis requires a comprehensive process that can only be
performed by professionals. Conducting such a survey independently without the
appropriate qualifications and equipment can lead to unforeseen problems.
A thorough soil survey allows you to develop a project that
takes into account all site features and avoids mistakes at the initial stage.
This helps prevent structural damage, uneven foundation settlement, damage to
utilities, and other problems that may arise in the future.
Removing a support to
adjust the foundation height
Removing supports to adjust the height is a common mistake,
especially among inexperienced installers. This error can significantly reduce
the load-bearing capacity of the supports. When the supports are unscrewed,
loose soil forms under their blades, and the working element is no longer
anchored in the supporting soil layer, leading to structural instability. The
piles thus begin to "loose," reducing the reliability of the entire
foundation. The more such supports there are in a pile field, the less reliable
the foundation becomes.
Pile Deviation from
the Vertical
Pile deviation from the vertical is a common problem when
installing a screw pile foundation. Although the installation process requires
precise calculations, minor deviations are acceptable, but they should not
exceed 2 degrees vertically and 4-5 cm horizontally, according to regulations.
Pile deviation can be caused by various factors, including
defects in the support structure, the presence of hard inclusions in the soil,
or errors in the installation process. To prevent such problems, it is
recommended to carefully inspect the piles, order installation from reputable
teams, and conduct a preliminary soil survey.
Pile deviation from the vertical position is monitored
during the screw pile installation process. For this purpose, it is recommended
to check the support's position after every second turn using a level. When
installing manually, it is optimal to have at least three people involved in
the screw pile installation: two screw the pile in, and a third checks for
deviation.
Installing piles in pre-dug holes
On the one hand, the automated process of installing screw
piles simplifies the work of installers and eliminates additional physical
effort. However, on the other hand, this approach can result in less secure
anchoring of the pile, especially if the hole diameter is wider than the
support itself. As a result, the pile is less securely anchored, which can
significantly reduce its load-bearing capacity, especially if a pilot hole is
used. In such cases, the screw piles may fail to withstand the expected load,
increasing the risk of foundation problems.
Avoiding backfilling
the pile cavity
Protecting the external surfaces of helical piles with an
anti-corrosion coating plays a key role in maintaining their durability.
However, inside the pile, the metal structure remains unprotected. This creates
conditions for condensation to form, which, accumulating in the pile cavity,
can cause corrosion of the metal, reducing its service life. Moisture from the
environment can also penetrate the pile, especially if it is not sufficiently
sealed. In cold weather, the water can freeze, expand, and damage the metal
structure.
To extend the service life of helical piles, it is
recommended to fill them with a dry cement-sand mixture. This method provides a
higher density than liquid concrete or semi-dry mixtures, allowing air to be
displaced from within the pile and preventing condensation from forming on its
inner walls.
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