Secant Walls | Secant Wall Construction | Complete Guide

Secant Walls

Secant walls are the traditional technique used to construct retaining walls, especially in areas with hard soil.

In this article, we will talk at length about these Secant Walls that support these engineering constructions without respite. Read the article until the end to find out everything you need to know about the secant walls, advantages, and disadvantages of secant walls.

Ever wondered how those standalone, Underground story, framed bridge heads, and other constructions are unwavering no matter what they are put through.

What are Secant Walls?

Secant Walls or Secant Pile Walls are constructed of intersecting buttressed concrete piles for strengthened support. Steel rebars or steel beams bolster these secant piles up, and then they are augured using machinery or hand augers. The piles are reinforced with steel rebars and constructed with the process of drilling.

As for the installation of such piles, primary ones are given priority, followed by secondary ones, and such overlap is in the order of 8 cm. These piled walls are regarded as retaining walls for ground retention before any excavation process goes underway.

The secant pile wall is also known as the retaining wall, which is usually constructed for the retention of the ground before the excavation is carried out to construct the foundation of the structure.

The secant pile wall is generally made from steel and timber, and they are constructed according to the slope of the foundation row is offset from the first. The purpose of using this type of design is to provide proper drainage between the piles and to prevent the water from saturating.

Secant pile wall is used in areas having high water tables. It is made from water-resistant materials.

The secant walls are used as an alternative to the diaphragm walls where the space available is limited. The secant wall are very flexible in shape. The secant pile walls are formed by the construction of the alternative unreinforced piles.

Also Read: What Is Pile Foundation? | Uses of Pile Foundations | Types of Pile Foundations |

Secant Wall Construction

In order to build these Secant pile wall, you need to keep a few considerations in mind and following the steps mentioned below:

1. The first step involves the Secant Wall Construction of guide walls to draw up the positioning of secant pile walls. This first step acts as the guiding one to the rest.
2. Once the guiding walls are set up, Vibro-hammer sticks a casing into the ground, and about a meter length of the casing is left off from the ground.
3. Over here, augers/drilling machines are brought to get rid of the soil coming in the way of the casing and form a primary borehole. The soil around the borehole is under propped by a casing that was previously installed.
4. For the formation and strengthening of the primary pile, concrete/cement is cascaded down the borehole.
5. Now it’s time for the installation of secondary boreholes. Over here, the casing of the two primary bored piles is taken out using Vibro-hammers to make space for a secondary bored pile. These two bored piles are now adjacent to each other.
6. Once the two boreholes are fitted, a steel cage is positioned within the secondary boreholes.
7. Upon finishing the steps described above, secondary bore holes are concretized using concrete or cement.
8. From 2-7 steps are repeated until the entire length of Secant piled walls are placed, and the work is brought to a satisfactory end.

These are the steps to undertake for a perfect Secant Wall Construction.

Also Read: What is Mat Foundation? | What Is Mat Foundation Used For? |Types of Mat Foundation | Construction of Mat Foundations |

Uses of Secant Piled Walls

There are quite a few uses of such walls, and all of them are self-explanatory. However, the following ones are the most pronounced:

1. The uttermost Use of Secant pile wall is to provide consistent support to various constructions like standalone, storey, and other deep foundations as without such piled walls, they would not be steadfast.
2. The Secant wall is constructed as a retaining structure used as a supporting component for the deep foundations.
3. The next most important Use of such walls is to resist overflowing levels of groundwater for which CFA techniques or CFA technologies are required.
4. Alternatively, these are called load-bearing walls to hold up the weight of deep foundations, as already highlighted in the first few points.
5. The secant pile walls are used to create permanent or temporary retaining walls, and they are formed by placing piles that are directly adjacent to one another.
6. The secant walls are also used as an alternative to the diaphragm walls where the obstructions are anticipated, and the space available is limited.
7. The secant pile walls are used to establish good lateral stability of the wall. The wall is made from the molded concrete unit with an internal row of steel helical pipes.
8. It helps to determine the height of the embankment, which helps in the effective control of the seepage of the water.
9. The secant pile walls retain the material or the filling from the large excavations.
10. The secant wall is used to construct the retaining walls, which are perpendicular to the ground.

Also Read: What Is Retaining Walls? | Uses of Retaining Wall | Types of Retaining Wall | Advantages of Retaining Wall

Advantages of Secant Piled Walls

There are various benefits of installing Secant piled walls. A few of the major ones are specified in the following points.

1. One of the highlighted advantages of secant walls is when it is set against sheet piles. As compared to sheet ones, these have an increased wall stiffness, so no matter what, your buildings will stand upright.
2. There is no doubt how some stories or accommodative spaces prove to be gravely difficult to erect because of the ground. Opting for Secant piled walls in major deep foundation undertakings with difficult grounds(boulders/cobbles)brings you better and fast results. If you’ve signed a contract to construct buildings on either of these, Secant Piled walls will provide you with better support.
3. Construction works can be real galling, especially with the constant drilling, Vibro–hammer, and other sounds. Installation of Secant Piled Walls involves minimal construction noise, and the activities are carried swimmingly without anyone noticing or getting the feels there’s some sort of construction work is taking place.
4. The construction of the Secant piled walls creates less noise as compared to the traditional method of the construction of the pile wall foundation.
5. The construction of the secant walls requires very little time.
6. The secant walls are much stiffer and stronger as compared to the traditional method of the construction of the retaining walls.
7. The secant walls are constructed with good alignment, due to which there are no chances of deformation.
8. The secant walls can be installed in the areas having cobbles and boulders.

Also Read: What Is Pier and Beam Foundation? | Difference Between Pier and Beam Foundation Vs Slab Foundation

Disadvantages of Secant Piled Walls

1. Though they are more durable and steadfast as compared to sheet piles, the cost is nothing to sneeze at. These support piled walls cost quite a lot in comparison to the sheet piles.
2. The next difference lies in their lack of fully waterproof, even more so in joints, and for this reason, they face disdain.
3. If deep piles are buried down the ground, it’s pretty unsure if verticality is tolerable or not, and for this reason, sometimes these Secant piled walls are passed over.
4. The waterproofing method done for the secant pile walls is not satisfactory as the faces of the concrete in contact with the ground can get wet and cause several issues.
5. It does not have enough resistance to the water pressure.
6. To further elaborate, when these Secant piled walls are constructed using steel beams, weaker than normal concrete is required and used.

These are the disadvantages of Secant piled walls that may very well influence one’s decision.

Also Read: What Is Shear Wall? | Purpose of Shear Wall | Function of Shear Wall | Types of Shear Wall | Advantages & Disadvantages of Shear Wall | Application of Shear Wall

Secant Piled Walls Vs Tangent Piled Walls

• Secant Piled Walls come in handy in cases where fleeting water retention is required. In such cases, these Secant piled walls provide a better alternative, for the installation and erection is cost-effective and quick as well.
• Whereas, Secant Walls, on the other hand, are preferably better alternatives when confronted with diaphragm wall construction tasks. This is the major polarity between these two walls.
• However, there is another piled wall as well, namely Tangent Pile Walls. These piled walls are constructed without any overlap of 3 inches, unlike Secant Pile Walls.
• Talking of the advantages of this alternative, they are much quicker and easier to set about. However, the tangent pile wall lacks in terms of its capability to hold up water levels, for this needs dewatering of the groundwater to manifest better results.
• The secant piles walls do not intersect and all the tangent piles are required to be reinforced. The tangent pile walls help to increase the flexibility of the construction alignment.

Are Secant Piles Load Bearing?

The secant piles are embedded retaining walls structures that are constructed to enable the deep excavation in the water-filled ground situations.

The piles are installed in a specific sequence to construct the walls. The soft piles are erected initially, which are followed by the hard piles, which overlap and cut through the two soft piles on both sides.

In difficult drilling conditions, the secant piles are proved to be a very economical method for cutoff wall construction.

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Frequently Asked Questions (FAQ)

What Are Secant Piles Used For?

The uttermost Use of the Secant pile wall is to provide consistent support to various constructions like the standalone, story, and other deep foundations as without such piled walls, they would not be steadfast.

Are Secant Piles Permanent?

Reinforced and non-reinforced piles are used in secant piles walls. Sometimes secant walls are used by anchor or stringing systems as a permanent or temporary retaining wall.

How Deep Do Secant Piles Go?

Using CFA or LDA technology, depending on the soil conditions, can be done from about 600 mm to 1180 mm in diameter, up to 60 m with secondary pile (male) up to a depth of 24 m (primary pile).

How Do Secant Piles Work?

The secant piles are embedded retaining walls structures that are constructed to enable the deep excavation in the water-filled ground situations.

What Is a Secant Pile System?

The secant pile wall is also known as the retaining wall, which is usually constructed for the retention of the ground before the excavation is carried out to construct the foundation of the structure.

The secant pile system is embedded retaining walls structures that are constructed to enable the deep excavation in the water-filled ground situations.

Are Secant Piles Temporary?

When deflection criteria are tight, secant pile walls can be retained by anchors or strutting systems either as temporary or permanent retention.

Is Secant Pile Wall Waterproof?

Secant pile wall is a new and growing technology in construction for the construction of underground walls. The use of Xypex products provides a cost-effective and easy way to waterproof the underground structure of the secant wall.

How Are Contiguous Pile Walls Constructed?

The piles are installed in a specific sequence to construct the walls. The soft piles are erected initially, which are followed by the hard piles, which overlap and cut through the two soft piles on both sides.

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