Underpinning is a technique used to stabilize and strengthen the foundation of an existing structure or building. It is a complex and highly technical process and should only be performed by experienced professionals of a reputable constructions company Gold Coast. It is necessary for various reasons such as increasing load-bearing capacity, bolstering foundation, etc. There are various methods to underpinning and it isessential to choose the one that is suitable for the building and soil type.
There are several reasons why a constructions company will perform underpinning for a building or structure. Some of the most common reasons are:
Structural Damage
Underpinning may be necessary when a building or structure has experienced structural damage due to natural causes such as earthquakes or flooding, or due to human activities such as construction or excavation nearby. Structural damage can cause the foundation to become unstable, resulting in cracks in the walls, ceilings, and floors, and in severe cases, the building may become unsafe and uninhabitable.
Unsuitable Soil
Soft or unstable soil can lead to cracking, settling, and instability of the foundation of the building. This can be due to a variety of factors such as soil erosion, poor soil compaction, or an insufficient depth of suitable soil. You can identify unsuitable soil condition during the soil testing phase of construction, or after the building constructionwhen signs of foundation problems become noticeable.
Soil Movement
Soil movement can occur due to a variety of natural causes, such as changes in water levels or erosion, as well as human activities like construction or mining nearby. Soil movement can bring about issues with the foundation or underpinning of a building likesettling, cracking, and instability. When soil movement is the cause of foundation problems, underpinning may be required to fix the problem.
Building Extension
When an extension is added to a building, the load on the foundation increases. But if the foundation is not capable of supporting the additional load, it can lead to instability and structural damage. A constructions company uses underpinning to increase the load-bearing capacity of the foundation as well as to ensure that the building can support the additional weight of the extension. Building extension can be adding a new room, floor, or an additional structure to an existing building.
Improper Construction
Improper construction can cause settling, cracking, instability, and other issues, which can lead to the need for underpinning. This can be due to poor construction techniques, poor soil conditions, or failure to follow building codes and standards. It is crucial to identify and address any issues with improper construction as soon as possible to ensure the structural integrity of the building and prevent further damage.
Vibration and Noise
Underpinning may be needed when a building or structure is experiencing vibration and noise due to heavy traffic or industrial activities nearby. Over time, vibration and noise can cause damage to the foundation and structural elements of the building and can also causediscomfort for the occupants. The choice of technique of the constructions company will depend on the specific situation, soil conditions, and the type of building.
Underpinning Methods
Some of the most common techniques used for underpinning include:
Pile underpinning.This involves driving steel or concrete piles into the soil beneath the existing foundation to provide extra support. The process starts by drilling or excavating holes for the piles at predetermined locations beneath the existing foundation. Using a pile driving rig, steel or concrete piles are inserted into the holes and driven into the soil. The piles are driven to a depth that reaches a stable soil layer. Once the piles are in place, they are connected to the existing foundation with the use of a load transfer platform or a reinforced concrete beam.
Mini Pile method.The process starts by drilling or excavating holes for the piles at predetermined locations beneath the existing foundation. The mini piles, which are typically smaller in diameter compared to traditional pilesare inserted into the holes and driven into the soil. The piles are usually driven to a depth that is sufficient to reach a stable soil layer. Similar to pile underpinning technique, the piles are connected to the existing foundation.
Mass concrete underpinning.This involves excavating below the existing foundation and filling the void with concrete. The constructions company starts excavating a trench underneath the existing foundation. The trench is filled with concrete, and the concrete is allowed to cure before the next section of trench is excavated and filled. The process is repeated until the entire area beneath the foundation is filled with concrete.
One of the benefits of mass concrete underpinning is that it is a straightforward and inexpensive method. It can be used in a variety of soil conditions and is ideal for small-scale underpinning projects.
Beam and Base method.This entails installing a reinforced concrete beam below the existing foundation, with the base of the beam resting on piles or piers that are driven into the soil. It requires excavating a trench beneath the existing foundation and then installing the piles or piers in the trench. Afterwards, the base of the beam is placed on top of them and connected to the existing foundation using a load transfer platform. This transfers the load of the building from the existing foundation to the piles or piers.
Grout Injection method. The process involves installing steel plates and anchors beneath the existing foundation, to provide additional support. The process starts by drilling or excavating holes at predetermined locations beneath the existing foundation. A grout mixture, usuallycomprises cement, water, and other additives, is injected into the holes under high pressure. The grout fills the voids underneath the foundationand hardens to form a solid mass; thus, giving additional support to the foundation.
Plate Anchor method.This involves placing steel plates and anchors beneath the existing foundation to offer additional support. The constructions company drills or excavates holes for the anchors at predetermined locations below the existing foundation. Then they insert the anchors into the holes and drive into the soil using a pile driving rig. After that, they will connect the steel plates to the anchors, causing the load of the building to be transferred from the existing foundation to the plates and anchors.
