Classification and design of bored piles and their advantages

Since they provide the structural support for a variety of structures, bored piles are a crucial component of contemporary construction. These drilled deep foundation components provide stability even in difficult soil situations. Selecting the best option for a given construction project can be aided by having an understanding of the various bored pile types and designs.

Bored piles fall into various categories, each intended to fulfill a distinct purpose. The variety, which includes under-reamed and straight-shaft piles, guarantees that there’s a suitable

Scope

There are several situations in which using bored piles makes sense:

• In a city environment next to already constructed objects, where there is a danger of destruction of surrounding buildings due to “heavy” work.
• On sites with limited space where it is difficult to move and install driven piles.
• When building on a slope.
• At sites where dense soils are observed on the construction site.
• When it is impossible to drive or vibrate piles due to natural soil with frequent boulders.

Advantages of bored piles

The following benefits serve as a guide when selecting bored piles:

• Minimal impact through the ground on the foundations of surrounding buildings.
• Absence of destructive phenomena on communications located underground.
• The piles are laid at the depth of freezing of the soil; this will help prevent their heaving, which threatens cracks on the facade.
• No need to remove soil from the construction site.
• Low level of vibration and noise, allowing work to be carried out near residential buildings.
• Long service life.
• High production speed.
• Reducing the cost and reducing construction time.
• The technology does not harm the surrounding terrain and is applicable on uneven soils and poor soils.

When building on unstable soils, bored piles—a kind of deep foundation—are crucial for supporting large, weighty structures. The various varieties of bored piles, their design concepts, and their special advantages—like their high load-bearing capacity and low vibration during installation—will all be covered in this article. By being aware of these factors, engineers and builders can select the ideal pile for their projects, assuring stability and durability for a range of building types.

Classification and design of bored piles

Concrete and reinforcing bars are the tools used in the technology of bored pile construction.

The techniques used to create a foundation depend on the kind of underlying soil at the construction site:

• Dry method. Used for piles that do not require preparation to strengthen the walls of the wells. It is recommended to use for soils that do not slide when drilling a well and do not collapse after and during concrete pouring. An example of such soils: clayey soils are tightly plastic and have a semi-solid to hard consistency.
• Strengthening the walls of wells with increased water pressure or clay solution. The method is used against caving when cutting through water-saturated unstable soils (clayey soils of soft plastic and fluid plastic consistency).
• Using tubular shells (pipe concrete). Used in construction on water-saturated heterogeneous clay soils of fluid consistency with layers of sand and sandy loam. Application in the construction of especially critical structures and during construction in areas covered with water.
• Using casing pipes. Used in weak, watery soils and with high groundwater levels.

Technology for installing bored piles with casing

Borehole casing pipes are a kind of metal frame that is submerged in the well and serves as a means of greatly reinforcing the entire structure.

To reduce the risk of the latter, such a foundation is typically utilized when constructing a residential building with a dense neighborhood. With the exception of rocks, the technique works well with loose, unstable soils. Its viability is limited to soils where passage without inflexible protection is not necessary and where employing lighter techniques is not feasible. There is heavy construction equipment used in the work. Installing piles without casing pipes occurs on comparatively stable soils.

The following procedures are involved in installing bored piles with casing pipes:

1. The drill makes a hole of the same diameter as the casing pipe.
2. Then the pipe is pressed into the ground and the soil that has fallen inside is removed from it.
3. Since, in order to immerse a pipe to great depths, equipment is needed, which can develop enormous forces, the process technology provides for alternating lowering the pipe with the operation of drilling out rock.
4. When the well is completely ready, the reinforced frame is lowered into it and then the casing is filled with concrete.
5. When the concrete is poured, the casing pipe is removed from the ground.

Technology for installing bored piles with a grillage

A combination of foundation types is referred to as the foundation on bored piles using a grillage. During its manufacturing process, bored piles are normally poured into the wells, and on top of them, a grillage is also poured. This allows the load to be distributed evenly across all of the piles at once.

This technology is suitable for areas with highly branched underground communications and weaker, complex soils; it should not be used in earthquake-resistant areas. Because it is difficult to drill wells for piles, you will need to schedule water removal measures right away if the groundwater level is high, even during the design phase of the construction site.

• Short. Completely goes into the ground below the freezing level, and the upper contour is equal to ground level.
• Elevated. Layed level with the ground.
• High. The sole is significantly higher than the ground by 20-30 cm.

Prior to constructing this kind of foundation, it is important to research and understand the following information:

• Type of underlying soil at the construction site.
• Location of groundwater.
• Soil moisture saturation.

They use data to design foundation characteristics and come up with the following values:

• Pile depth.
• Cross-section of grillage and piles.
• Gap between piles.
• Reinforcement of piles and grillage.

Horizontal reinforcement is fastened to the reinforcing bars that have been previously taken out of the piles in order to build a bored foundation with grillage. The formwork needs to be installed and ready for use. The thickness of the wall determines the width of the grillage, while the estimated weight of the house determines its height. To strengthen the completed formwork, concrete is poured into it and left for at least 15 days.

The greater load-bearing capacity of bored piles with grillage is an advantage. The foundation’s base is perfect for a brick residential building because it can support loads from even the heaviest structures.

Applying a waterproofing layer to the grillage is essential to prevent materials with different properties from being destroyed between the concrete and the house walls.

Manufacturing technology of bored piles with a monolithic grillage

Multi-story buildings are constructed on a foundation of bored piles with a monolithic grillage, which is created in the following order:

Site marking

The soil’s plant layer is eliminated, and the area is cleared. Wooden cast-offs are positioned at predefined intervals along the exterior of the future home. It has a cord attached to it that indicates the house’s axes.

Drilling wells, reinforcing and pouring piles

Following the markings and a predetermined depth calculation, formwork is set up and reinforcement is completed. After loose soil is removed from the bottom using a hand drill driven to the design depth, a rammer is used to create a 30–50 cm thick layer of sand. After the reinforcement is in place, we start to pour concrete. In 20 to 25 days, this foundation will be completed.

Polystyrene foam boards are a good way to insulate the foundation of the house and create a proper microclimate. Insulation is only necessary for the portion of the foundation that comes into direct contact with the house. Thermal insulation is applied to the blind area concurrently, which helps to keep the foundation dry and warm.

Subject to technological advancements, the brownish foundation will endure for at least a century.

Buronabish pile manufacturing technology with tape grillage

Since each support in a brownizer pile functions independently, there is a greater chance of uneven shrinkage, which is dangerous for homes. Strip grillage made of reinforced concrete is used to prevent such wall destruction. The distinction lies in the way reinforcement joins all supports to form a comprehensive base that precisely senses the bending moment.

The following is the installation order for a strip foundation with bored piles:

1. A pillow of sand and crushed stone with a thickness of 20-30 cm is arranged along the perimeter of the strapping.
2. Wooden formwork is arranged on top, on the inner walls of which rolled waterproofing is laid.
3. A frame is assembled from reinforcement bars, laid in the formwork, and attached to the ends of the pile reinforcement.
4. Pouring the grillage with concrete mortar in one step with further compaction and 30-day strength gain.

Differences between foundations with bored piles depending on the material of the house

The thickness is the only notable distinction between brick and wood foundation construction technology. This is because walls and floors were constructed with lighter construction materials.

In many cases, bored piles provide a reliable foundation option for building projects. They are made by excavating a hole in the ground, filling it with concrete, and occasionally adding steel reinforcement. This technique ensures that buildings stay secure and stable by providing a strong foundation, particularly in areas with unstable soil.

The primary benefit of bored piles is their versatility in handling different types of soil. Bored piles can be customized to meet the unique needs of the site, regardless of whether they are dealing with loose soil, sand, or clay. They are therefore a flexible option for both commercial and residential structures.

Furthermore, compared to other foundation techniques, the installation of bored piles causes less disturbance to the surrounding area. That implies fewer

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