Underpinning Methods, Procedure, Use in Foundation Strengthening and Repair

It is an important construction method that can be used for either strengthening a foundation already in place or placing a foundation deeper below the existing one.

It is important to select the best method when underpinning a building. In order to choose the best method, you need to be able understand and evaluate the soil strata. You also have problems with the whole foundation.

The underpinning method can also replace the vulnerable Foundation by transferring it to a new depth and a lower level.

The underpinning method can be applied to repair a weak foundation by transferring the existing foundation bearing labels roll down to a lower level.

The preparation before the underpinning is essential

The proposed work must be notified to the neighboring property owner or the not with specifics about typical use and the underlying action.

Should you decide to carry out the survey, please visit the site. At that point, the results of any cracks will be recorded and sent to adjoining owners.

If the foundation is settlement, then it’s important to determine the purpose of the underpinning and how you will proceed.

Meri can be used to decrease the weight of the building by removing the dead and unwanted loads. This is done by using props, or by installing shoring.

The area vulnerable to underpinnings should be identified, tracked, marked or exposed.

Need for underpinning

1.Uneven settlement is due to the unsymmetrical load of the building and the uneven bearing capacity of soil under the foundation.

2). Increased loading: The loading of building men changed because of an addition of another story, or a change to the imposed load due to a change in the service loading.

3). You can lower adjacent foundation: If the work is not available, you need to lower nearby the foundation.

Underpinning Methods

You can carry out the underpinning in a few different ways:

1.Pit method

2).Pile methods

3. Underpinning of walls

4).Jack pile underpinning

Needle and pile underpinning

6). “Pynford” Stool method

The root pile is also known as the angle Pile.

The Pit Method

The entire foundation length is subdivided into sections ranging from 1.2 m to 1.5 m in length. The section of the foundation is worked on one by one.

A hole must be made first in all wall sections that are above the level of the plinth. Next, an needle should be inserted into the hole. The needle can be made out of steel, wood or stout material. Above the needle, bearing plates support the masonry. Crib supports are placed on the walls and screw jacks to support the needle.

A foundation pit must then be dug up to the new level needed for the new foundation. After that, the foundation pit is excavated and the new one laid. The work should include some important safety precautions, including raking walls, providing shores for the floors and securing them.

In the pit method, it is important to consider:

1). The first round is devoted to alternate sections. After that, you will take the intermediate sections. One section at a given time is recommended.

2). In the case of a wall that is extended both ways, it’s better to work at the middle.

3). In the case of a deeper foundation, the trench for the foundation can be timbered.

4). Once the foundation reaches its full strength, only then should the needle beams or other structures be installed. Remove the materials slowly.

Pile method

The Pile method is a technique of strengthening walls by installing piles using a proper driving technique. The pile technique that is most commonly used involves the use of borehole piles on under-reamed pilings.

Finally, the needles of steel or concrete are inserted into the wall. They are attached to the pile. They can also be used to cap piles.

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