Bored pile foundation: selection of piles, layout and calculation, step-by-step installation instructions

Due to its strength and adaptability, a bored pile foundation is a popular option for many types of construction projects. In order to create sturdy support pillars, this kind of foundation entails drilling deep holes in the ground and filling them with concrete. It is particularly helpful in locations with unstable soil or high load-bearing needs.

The success of your foundation depends on the type of piles you select. Your decision will be influenced by various factors such as budget, load requirements, and soil conditions. Bored piles are available in different lengths and diameters, making them suitable for a range of building types. Making the right choice guarantees the longevity and stability of your structure.

The next stage is to plan the arrangement of your piles once you have selected them. This entails figuring out how many piles are required and where they should be placed. The weight of the structure is distributed evenly and uneven settling is avoided with a well-designed layout. Building a solid foundation requires careful planning and calculation.

Installing a bored pile foundation requires a number of meticulous procedures. Every step, from drilling the holes to installing the reinforcement and pouring the concrete, needs to be done precisely. By carefully following the instructions, you can make sure that the foundation is constructed correctly and will give your construction project the support it needs.

Topic	Details
Selection of Piles	Choose the right type of piles based on soil type and load requirements. Common types include concrete, steel, and composite piles.
Layout and Calculation	Determine the number and spacing of piles by calculating the load each pile must support. Use a grid pattern for uniform load distribution.
Step-by-Step Installation	1. Drill holes to the required depth. 2. Place reinforcement cages if needed. 3. Pour concrete into the holes. 4. Allow the concrete to cure before proceeding with construction.

Pros and cons of bored pile foundations

The following benefits come with using a bored pile:

1. No need for additional work on leveling the soil and constructing a trench or pit. If we compare it with a foundation such as a strip foundation, on bored piles the foundation requires less preparation costs, since the device of the strip type requires a flat surface and a large amount of excavation work.
2. Low cost of installation work, low consumption of materials in comparison with a slab foundation.
3. High speed of work. They can be completed in 12 hours, depending on the features of the object and the properties of the soil on the site. For the concrete mixture to harden, 8 days are enough, while the strip foundation will harden within a month.
4. No need for additional waterproofing, which also helps to reduce costs.

Furthermore, installing a bored type eliminates the need to find a spot to store piles, which is crucial on a small site. The foundation has a one hundred-year service life. This is a long time for frame homes and private construction.

However, there is a disadvantage to this kind of foundation as well: even under identical geological conditions, different types of piles can have 30% different bearing capacities. This makes figuring out a pile’s bearing capacity more difficult.

Bored or screw piles: which is better?

The two types of foundations used for building on soft, marshy, and subsiding soils are screw and bored. The question of which is superior is hard to answer.

Screw piles are thought to be a more dependable structure with a high design load capacity. They can be installed more quickly than bored piles and require no additional time for the solution to harden. They can support a full load right away.

Screw piles can be fixed, though it’s a relatively easy procedure. If needed, they can also be reused. Conversely, they are significantly more expensive than a bored pile foundation, which is a drawback.

Calculation and layout of bored piles

The developer must be aware of the features of such a foundation’s design if he chooses to create a bored pile version by hand. Therefore, beneath every load-bearing wall, bored piles are installed in rows; these piles must be placed at the corners of the future home.

You must account for the soil’s structure and the structure’s weight when determining the diameter, quantity, and necessary spacing between the piles. The best bearing capacity soils are semi-rocky and rocky. More piles are needed for loamy, sandy, and clayey soils.

You must compute the weight of the building materials—including the roofing "pie"—used in the construction of the future structure in order to ascertain its weight. For this, there are SNiPs and unique reference tables.

The weight of the house will determine how many piles need to be installed and how close together they should be spaced.

At least three times the diameters of the piles should separate them. The foundation’s bearing capacity will be lowered if the supports are put in with smaller steps.

DIY bored pile foundation

You must follow the algorithm and building codes when installing a bored pile foundation.

Step-by-step instructions for installing a bored pile foundation

The future foundation is first drawn out. Formwork panels are removed from boards and beams for this purpose. Two levels make up this type of design: the top edge of the grillage is indicated on the first level, which shows the height of the piles.

Establish the reference point, which may be the site’s border or a fence that has been erected there, from which the counting will be done. Next, draw the foundation’s base lines; these will contain the building’s walls. After that, a string is pulled between the formwork panels once they are installed.

The angles between neighboring partitions should be checked; they should be straight.

After marking the pile locations according to the project, a plumb line is lowered from the string, and reinforcing pegs are driven in beneath it.

Next, the following categories of tasks are completed:

• well drilling;
• installation of casing pipes;
• reinforcement of piles;
• their concreting;
• cutting of casing pipes.

The above-ground portion of the future house’s foundation is installed at the last stage.

Drilling wells and installing casing pipes

In private construction, drilling can be done manually or with the aid of specialized equipment.

You can drill a well that is between 15 and 45 cm in diameter using a hand drill. In order for the wells to be at least 0.3 meters below the freezing point of the soil, you must drill to a minimum depth of 1.5 meters.

When the well is prepared, construct a casing pipe. You can use roofing material for its device. The casing’s length should be 50 cm greater than the well’s depth, and its diameter should nearly match the well’s. Several layers of roofing material are used for the upper portion of the pipe, and they are pulled with wire. Formwork for the next pile, which is positioned in the well until it stops, is revealed.

Reinforcement of brownish piles

If a pile’s length can reach several tens of meters and its diameter must be at least one meter in industrial or multi-apartment residential facilities, then in private construction, piles with a diameter of 0.35 meters and a length of 2.5–3 meters are typically utilized.

In this sense, it’s crucial to keep in mind a few guidelines when strengthening such a foundation:

1. The total length of the reinforcing frame can be less than the pile length no more than 10 cm.
2. The ligation of the longitudinal reinforcement with horizontal jumpers should be carried out every 70 cm. At the same time, welding is not always used for connection, sometimes knitting wire is enough.
3. For reinforcement, either 3 rods of ribbed reinforcement with a cross-section of 14 mm or 4 rods with a cross-section of 12 mm are used . For transverse lintels, smooth reinforcement with a diameter of 6-8 mm is used.

The necessary amount of reinforcement is calculated during the design phase.

Concreting of bored piles

Concrete can be poured into the casing pipe to form the pile after the reinforcement bundle is installed. For these uses, a mixer works best because it is made for producing large-scale concrete projects.

During the design phase, an appropriate material is chosen; for these uses, concrete grade M100 or higher is typically utilized.

It is advised to use a deep vibrator to process each layer in order to prevent voids from forming inside the mass. Preparing small amounts of concrete at the same time as the previous layer is rammed in place is preferable.

Device of the heel – the base of the bored support

You can widen the heel, which is the base of the support, to increase the pile’s load-bearing capacity by five to ten percent.

Two approaches can be used for this:

• spreading the soil at the wellhead, after which reinforced ramming is performed, and then the concrete mixture is poured;
• casing pipe of such a design that a widening is obtained at the bottom.

It is challenging to maintain control over the final structure’s quality in the first scenario. Since a wider well must be drilled in the second case, the quality will be higher but the labor intensity of the work will also increase.

Such widening is not required when constructing a relatively light private home.

Cutting casing pipes and reinforcement

A grinder is used to cut reinforcement and pipes. All of the reinforcement rods should be the same height and protrude from the completed pile. Connecting the piles to the above-ground portion of the foundation requires doing this.

Heavy structures can be effectively supported by bored pile foundations, which provide strength and stability even in difficult soil conditions. To guarantee the success of the foundation, choosing the appropriate pile type, organizing their arrangement, and carrying out precise computations are essential stages. You can build a solid foundation for any construction project by carefully weighing these considerations.

The distribution of the load and the properties of the soil should be taken into consideration when planning the pile layout. Achieving the intended load-bearing capacity requires proper spacing and depth. Adhering to guidelines and standards is crucial in order to prevent problems like uneven settling or structural damage.

Bore pile installation is a methodical process that includes drilling holes, inserting reinforcement, and pouring concrete. To maintain the integrity of the foundation, each step necessitates close attention to detail and adherence to best practices. You can steer clear of common pitfalls and build a strong, long-lasting foundation by taking a step-by-step approach.

All things considered, a bored pile foundation offers a strong and trustworthy choice for a range of building projects. You can build a foundation that satisfies the needs of your structure and guarantees its stability for many years to come with careful planning, precise calculations, and careful installation.

When building in regions with high groundwater levels or on unstable soils, a bored pile foundation is an essential option. This article will walk you through the process of choosing the appropriate pile type, creating a functional layout, and carrying out the required computations. A simple, step-by-step installation guide is also included to make sure your foundation is sturdy and dependable. Whether you’re a novice do-it-yourselfer or an experienced builder, this thorough guide will enable you to approach your next construction project with confidence.

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