Pile foundation: laying stable foundations

Understanding pile foundations: Basics, advantages and applications

What is a pile foundation?

Pile foundations are a construction technique that has its roots in history. Even the master builders of antiquity and the Middle Ages used this method to create stable foundations on difficult ground. With pile foundations, long, cylindrical elements – called piles – are driven deep into the ground. These piles are used to create a robust base for buildings, bridges, masts and other structures with heavy loads, among other things.

Why is the pile foundation important?

The load-bearing capacity of the soil varies depending on the location. Depending on the location, the subsoil can be stony, rocky, loamy or sandy, for example. Some floors are solid and can easily support the weight of buildings, while other floors are less stable and could give way. The pile foundation/deep foundation is necessary to ensure that tall or heavy buildings stand securely and do not sink or tilt.

How does the pile foundation work?

Pile foundations are based on the principle that deeper soil layers are often more stable than the upper layers. By inserting piles into these deep layers, the weight of the structure can be evenly distributed, reducing the load on the ground.

What are the advantages of a pile foundation?

Stability and load-bearing capacity: Pile foundations make it possible to create stable foundations on difficult or yielding ground. By penetrating into deeper, load-bearing soil layers, piles distribute the weight of the structure evenly, providing a solid base for buildings and structures.

Adaptability: Different building sites require different approaches. Pile foundations are extremely adaptable and can be customised to different soil conditions.

Time and cost efficiency: Compared to other foundation methods, pile foundations often require less complex ground preparation.

Versatile application: Pile foundations are used in a wide range of construction projects. From high-rise buildings and bridges to wind turbines and industrial plants – the versatility of this method makes it a proven choice for a wide range of construction projects.

Minimisation of subsidence: By penetrating into deeper soil layers, pile foundations can minimise settlements and subsidence, which ensures the long-term stability of the structures.

Where are pile foundations used?

Pile foundations are used when the upper soil layers are not sufficiently stable to bear the loads of the structure. In this case, piles are driven into the ground to transfer the loads to deeper, more stable layers. Deep foundations may be required in the following situations, for example:

• For high loads, such as high-rise buildings, bridges or wind turbines
• For layers with low load-bearing capacity, such as peat, lake clay or silt
• In the event of groundwater lowering, which can lead to a deterioration of the soil properties
• For earthquake risks that require increased safety

Clarity on costs: budgeting and financial planning for pile foundations

When it comes to building robust and durable structures, pile foundations are a proven method. However, it is crucial for building owners and project managers to keep an eye on costs and ensure accurate cost estimation and efficient financial planning of the building.

Factors that influence the cost of deep foundations

1. Soil condition: The condition of the soil at the construction site is a decisive factor. Different soil types require different pile types and lengths, which can affect the overall costs.
2. Pile material and type: Depending on the project requirements, different materials such as concrete, steel or wood can be selected for the piles. Each material has its own cost, and the choice depends on the geotechnical conditions.
3. Accesability and location: The accessibility of the construction site and the local conditions can influence the costs. Difficult terrain or confined spaces may require specialised equipment or additional measures that could increase the overall cost.
4. Depth of the pile foundation: The depth to which the piles have to be driven into the ground has an effect on the amount of labour required and therefore on the costs. Deeper foundations may require additional materials and more time.

Tips for estimating and managing costs as part of a construction project

To successfully estimate and manage the cost of pile foundations, consider the following tips:

1. Thorough site investigation: A comprehensive geotechnical investigation is essential to assess ground conditions and other factors that may affect costs.
2. Early involvment of experts: Get experts such as geotechnical and civil engineers on board as early as possible in the planning phase. Their expertise can help to provide accurate estimates.
3. Plan realistic buffers: It is advisable to plan a buffer in the budget for unforeseen expenses. Geotechnical conditions can change, which can cause additional costs.
4. Transparent communication: Keep communication between all parties involved open and transparent. Clarify financial issues at an early stage to avoid misunderstandings.

Importance of foundations: How deep foundations guarantee stability and durability

Deep foundations are an important measure for erecting structures on weak subsoil.

Avoidance of subsidence: Subsidence is the slow sinking of buildings. This can happen if the ground under the foundation gives way. This is often the case when building on unstable ground. Piles can prevent this. They reach deep into the ground and rest on stable layers that can support the structure. This ensures that the structure remains stable.

Avoidance of deformation: The floor can sometimes deform, for example due to water. This can damage the building. Piles are like solid supports that hold the structure up. They prevent it from deforming or cracking.

Durability of pile foundations: Pile foundations also play an important role in the durability of buildings. If piles are installed correctly, they can last for decades or even centuries. This means that buildings remain safe and stable over long periods of time.

The durability of pile foundations depends on various factors, such as the quality of the materials used and the correct manufacture and processing of the piles. If these factors are taken into account, pile foundations can help buildings to last for generations without developing serious structural problems.

Pile foundations are essential to make buildings stable and durable. They protect against subsidence and deformation by distributing the loads evenly across the substrate. The durability of pile foundations ensures that a structure remains safe and stable over long periods of time, making them an important component in foundation construction. It is therefore very important that the subsoil is thoroughly checked before construction and that the appropriate type of pile is selected.

The processing of the piles should not be underestimated for the longevity and durability of the foundation. The top part must be removed again after construction in order to be able to lay the connecting reinforcements. If handled incorrectly, the pile can be damaged during this process.

Standing pile foundation: Load-bearing capacity due to friction and load transfer

A vertical pile foundation is a common method for erecting structures on soft or watery ground. Piles are driven into the ground to transfer the loads of the structure to deeper, more load-bearing layers.

Analysis of the standing pile foundation as a common method

The vertical pile foundation is a variant of the deep foundation that is used when the soil layers close to the surface are not sufficiently load-bearing or when very high loads have to be transferred. With a standing pile foundation, the piles are driven into the ground to a depth of several tens of metres in order to achieve a stable layer. A vertical pile foundation may be required, for example, for

• High-rise buildings, bridges or wind turbines that generate very high loads
• Groundwater lowering, which can lead to a deterioration of soil properties
• Earthquake risks that require increased safety

A vertical pile foundation requires careful planning and execution to ensure optimum load-bearing capacity. The quality of the materials used, the correct manufacture and processing of the piles and the testing of the piles also play an important role.

Friction and surcharge load for pile foundations

Pile foundations are a crucial component in the stability of structures. Two key factors play a decisive role here: friction and load.

Frictional forces maximise the load-bearing capacity

Friction is caused by direct contact between the pile and the surrounding soil. This resistance counteracts the vertical movement and stabilises the structure. By optimising the contact surface between the pile and the ground, the load-bearing capacity can be significantly increased.

Ballast – additional stability through weight

The load refers to the weight bearing on the pile. The higher the load, the more stable the pile foundation will be. The load-bearing capacity of the foundation can be optimised through targeted planning and calculation of the load.

With in-depth expertise and precise planning, civil engineers can maximise the load-bearing capacity of pile foundations. Careful consideration of friction and load forms the basis for safe and durable structures.

Diversity at a glance: Different pile foundation types for customised solutions

Overview of different pile foundation types

There are different types of pile foundations that can be selected depending on the soil and project conditions. Choosing the right pile foundation is crucial and depends on specific soil and project conditions.

Piles by type of manufacture

Following the manufacturing process, piles are either drilled or driven into the ground. A distinction is made between prefabricated piles, cast-in-situ piles and bonded piles. Among other things we speak of:

• Bored piles: are drilled into the ground and filled with concrete.
• Precast driven piles: consist of pre-cast reinforced concrete and are driven into the ground.
• Cast-in-place concrete piles: are driven into the ground using a steel pipe and filled with concrete.
• Screw piles: are driven into the ground with a screw tip, displacing the soil.
• Displacement bored piles: is a relatively noise and vibration-free method of creating a foundation in soft soils.
• Micropiles: have a small diameter and are drilled or injected into the ground.

Piles made from different materials

Piles can be made from various materials such as wood, steel, concrete or reinforced concrete. The choice of material depends on the individual requirements and the given ground conditions.

Emphasising adaptability to different soil and project conditions

In a dynamic construction project environment, the focus on adaptability to different ground and project conditions is of crucial importance. For this reason, choosing the right pile type and material is crucial and depends on various factors:

• Soil properties
• Loads and loading of the building
• Building construction
• Environmental requirements
• Costs
• Building laws and regulation
• Aesthetic requirements

Profound decisions: When is a deep pile foundation the right choice?

A deep foundation is always necessary if the subsoil is not of a suitable quality for a building project and this cannot be remedied using other methods. This is the case, for example, if the load-bearing capacity directly under the structure is not given or if large settlements are to be feared. For example:

• Unstable soil conditions
• High loads that have to be taken on
• Areas at risk of subsidence
• Groundwater
• Earthquake-proof construction
• Poor surface conditions (swampy or wet areas)

The choice of pile foundation depends on many different factors, including the specific soil conditions, the type of structure and local building regulations. For example at:

• High-rise buildings, bridges or wind turbines that generate very high loads
• Peat, lake clay or swamp areas with very low load-bearing capacity
• Groundwater lowering, which can lead to a deterioration of soil properties
• Earthquake risks that require increased safety

In-depth investigation of deep pile foundations as a solution for particularly challenging soils

Demanding floors are often a challenge. In regions with loose or unstable soils, such as silty, clayey or sandy deposits, a conventional shallow foundation can quickly reach its limits. Settlement and instability can jeopardise the integrity of the structure.

Important factors in the realisation of the pile foundation are the following topics:

• Thorough soil analysis
• Quality of the piles
• Professional installation
• Regular inspections

Brextor®: Efficient, safe & high-quality pile cropping

Pile foundations are a complex and demanding task that requires a great deal of expertise and experience. But even after the piles have been installed, the work is not yet done.

With pile installation methods such as bored piles, cast-in-place driven piles or displacement bored piles, the uppermost concrete section must be removed from the pile and the reinforcement enclosed in the concrete exposed. This ensures an optimum connection with the floor slab.

Why over-concrete and not simply leave the required reinforcing bars exposed from the start?

During pile production, concrete is filled into the pile. The concrete mixes with dirt, sand and stones. This mixture floats to the top and must be removed accordingly. In order to comply with the guidelines, it is very important that a pure concrete and steel connection without foreign bodies is created. The reinforcing bars are appropriately preserved / protected by the concrete.

For this reason, it is extremely important that no damage is caused to the pile or the rebars when exposing the rebars. Corrosion damage or unstable foundations can be the result.

Pile production is extremely expensive!! Pile breaking costs a fraction of the pile production costs. Unfortunately, far too often and too many compromises are made when pile breaking.

There is no need to compromise when pile breaking with the innovative Brextor® methode!

With the patented milling process, the dismantling force is under control at all times. The core and surface tension is broken in a single work step. But that’s not all! Brextor® contributes to efficient and sustainable pile breaking:

🏗 Increased construction quality

Perfectly cut piles without cracks in the pile body or spalling on the pile outer skin, no bent or torn reinforcements and a height accuracy of +/- 1cm.

💵 Reduced construction costs

The demolition material consists of 80% gravel 0-30mm and can be reused directly on the construction site. In addition, Brextor^® requires less working space than conventional demolition methods. This not only saves costs for transport and disposal, including fees, but also eliminates the need to purchase and supply replacement material. Furthermore, the preparatory work is reduced by eliminating the need for a cut at the definitive demolition height, and the cleaning effort is much lower than with conventional demolition methods.

⏱ Shortened processing time A pile, for example, with a diameter of 1m and a demolition height of 1m can be processed within 40 minutes. This makes a daily output of up to 16 piles possible. In addition, Brextor^® provides reliable performance and thus increased planning reliability.

♻️ Environmental friendly

With Brextor^®, the demolition material (80% gravel 0-30mm) can be reused directly on the construction site. In addition, Brextor^®requires less working space. This saves excavation and replacement material. Due to the direct reuse of the demolition material on the construction site and the saving of excavation and replacement material, transports can be saved. In addition, landfills are less burdened.

👷 Increased health & safety protection

No heavy physical work is required for pile breaking, which massively reduces the risk of health hazards such as HAVS syndrome. In addition, Brextor^® avoids working in danger zones.

Summary

The pile foundation is crucial, as not every building site has sufficient load-bearing capacity. This allows stable foundations to be created as the basis for buildings, bridges and other structures. Cylindrical piles are usually driven deep into the ground. The pile foundation offers numerous advantages, including stability, adaptability, time and cost efficiency and minimised settlement.

Friction and surcharge are decisive factors in pile foundations that influence the stability of structures. Friction is caused by the direct contact of the pile with the ground and stabilises the structure by inhibiting vertical movement. An optimised contact surface between the pile and the ground significantly increases the load-bearing capacity. Superimposed load refers to the weight bearing on the pile and contributes to the stability of the pile foundation. Expertise and precise planning enable civil engineers to maximise the load-bearing capacity of pile foundations, which forms the basis for safe and durable structures.

Depending on the soil and project conditions, various types of pile foundations are available. From bored piles to screw piles, each method offers individual advantages that can be customised to meet specific requirements. For most pile types, the top part of the reinforcement must be exposed (cut). It is important that the relevant guidelines and regulations are complied with.

Pile breaking using Brextor® offers numerous advantages. With this innovative milling process, piles are processed gently, resulting in increased construction quality, reduced construction costs and shorter processing times. Brextor® is also environmentally friendly and contributes to health and safety at work, as no heavy physical labour is required.

The right choice of pile foundation method and professional pile breaking are crucial steps for stable and durable structures that can withstand a wide range of ground conditions.