Underpinning Of An Age Care Facility
Basics Of An Underpinning System For An Age Care Facility
Underpinning is the process of stabilizing, strengthening, and repairing an existing building%u2019s foundations which have been weakened due to a variety of factors. Underpinning repairs and reinforces the area beneath a load bearing foundation to make it stronger. There are many different types of underpinning which suit different types of repair projects. It is important to understand the structure of the entire foundation, the supports currently in place, and the type of factors that caused damage to the foundation before deciding which type of underpinning should be used.
There are a variety of reasons for underpinning the foundation of an Aged Care Facility, some of them being:
– Due to the decay of wood piles, the original foundation is no longer stable enough.
– There has been a change in how the structure is used.
– The properties of the soil that support the foundation have changed or were originally mischaracterized during the planning stages.
– Construction of structures nearby necessitates excavation of the soil that supports the existing foundations.
Soil subsistence usually occurs in low- and medium rise buildings with shallow foundations. Subsistence and settlement are terms that are used interchangeably to describe the sinking of the soil on which the structure was built. Rising ground can also occur causing movement known as %u2018heave%u2019. Depending on the cause for the subsistence or heave, horizontal squeezing or stretching of the ground may accompany this vertical movement. When movement becomes excessive it may compromise the use and safety of a building such as an Aged Care Facility and underpinning generally becomes the best solution.
Application and Benefits
The process of underpinning involves extending the foundation by digging beneath shallow footings and pouring concrete to extend the reach in depth and/or breadth in order that it is supported by a stronger soil stratum, or the load of the foundation is distributed more evenly across a greater area. Common methods of underpinning are jet grouting and making use of micro piles. Alternatively, underpinning can be done by the introduction of a grout to strengthen the soil.
There are 3 common methods of underpinning a foundation:
1. The traditional mass concrete method used for shallow underpinning involves excavation of the soil beneath the foundation and replacing it with mass concrete to provide more strength. In this way, the structural weight of the existing foundation is distributed in a more efficient manner.
2. Incorporating the use of a beam and base in conjunction with a mass concrete base construction. The load of the foundation is transferred to the concrete beam that has been constructed beneath it, then transferred to the mass concrete base and evenly spread underneath it.
3. Mini piled underpinning involves the transfer the load of a structure and its foundation to more stable soil found deeper underground. Piles are constructed and cased in steel and then driven into drilled holes to rest on the stable soil up to 15 meters below ground.
Underpinning is an option to soil treatment with techniques that bypass the problem of weak soil with the installation of structural elements that transfer the load of the building to underlying bedrock or competent soil. Foundation underpinning can be done in such a way that the aesthetics of the structure such as an Aged Care Facility are uncompromised.