The driven piles are a commonly-used form of building foundations that provide the support for structures. They are also called displacement piles. They transfer their loads to the layers of soil or rock which have sufficient bearing capacity.
They are used to support tanks, walls, bridges, buildings, and towers. They are the most cost-effective deep foundation solution. They can also be used in applications such as embankments, anchorage structures, retaining walls, bulkheads, and cofferdams.
If the depth of a foundation is more than three times its breadth then it is termed as piled. A long, slender column made of preformed material is a driven pile. It has a predetermined shape and size and it is installed by vibrating, impact hammering or pushing it into the ground to a design depth or resistance. Pre-drilling is required for enabling the pile to reach the design depth if the soil is dense.
The driven piles are very adaptable and they can be installed to accommodate compression, tension or lateral loads. The specifications are set according to the needs of the structure, budget and soil conditions. The driven piles have both advantages and disadvantages but the benefits surely outweigh its disadvantages. Let us have a look at them.
The advantages of pile foundation are as follows:
- They can be pre-fabricated off-site which allows for efficient installation once on site.
- They displace and compact the soil which increases the bearing capacity.
- The piles are cost-effective.
- The piles have a superior structural strength to other forms of foundation.
- The piles are ideal for challenging conditions such as wind, water, and seismic loading as they have a high lateral and bending resistance
The main disadvantages of using driven piles are:
- One of the disadvantages is that advance planning is required for handling and driving.
- Precast or pre-stressed concrete piles must be adequately reinforced for withstanding handling stresses during transportation and installation.
- If the ground has poor drainage qualities then the driving piles may not be suitable.
- The piles may not be suitable for compact sites as the foundations of structures that are near to each other may be affected by the vibrations caused by installation.
- They can be noisy to install and vibrations can result in complaints from neighbors.
- The exact length required for the piles may not be possible to determine and so the splicing or cut-off techniques may be required which adds to extra cost and time.
Types of driven pile include:
Steel
The box section piles or H-section piles can be formed using the Standard steel sheet pile sections. They are used mainly in connection with marine structures. These piles are having a load range of 300-1,700 kN. They can reach up to 36 m in length.
The Steel screw piles are having a cast iron helix. They are used for support at shallow depths in soft silts and sands. These piles have a load range of 400-3,000 kN. They are able to reach up to 24 m length.
Timber
The timber based piles can be used for small contracts on sites with shallow alluvial deposits overlying suitable bearing strata. They are usually percussion driven. Their load range is 50-350 kN. The timber piles can be up to 12 m in length without splicing.
Pre-cast concrete
The pre-cast concrete piles can be square, octagonal, cylindrical or sheet piles. These piles are percussion-driven piles which are used where bored piles would not be suitable owing to very loose soils or running water. They can reach up to 30 m and have a load range of 300-1,200 kN.
Composite
The composite piles use a combination, such as a concrete pile with a steel tip extension.
The driven piles require very good quality control. They are generally built using high-strength materials with precise tolerance. The BS 8004:2015 and EC standards are used to check whether the quality is as per the proper standards or not. Inspection is done before installation to verify the integrity of the piles.
It is highly important that driven piles maintain their shape during installation. They shouldn’t be damaged by the installation of subsequent piles.
To check the pile capacity, i.e., how much maximum load a pile can carry without failure or excessive settlement of the ground, the static or dynamic pile testing is used. The capacity of the pile depends on the following three factors.
- The method used for pile installation.
- The pile dimensions.
- The type of soil through which the pile is driven is also seen.
So, here was a detailed overview of the driven piles which can be an important material for robust construction work. Hope you got a clear idea about the pile foundation! To give you a detailed explanation about the piles, Architectures Ideas has brought this article. So, continue reading the article and know about the pile foundation in detail.