How to remove old deep concrete piles？

The methods for removing old deep concrete piles mainly include the following:

1. Pile pulling method

Applicable situation: when the diameter of the concrete pile is small and there are no important buildings or underground pipelines around.

Operation method:

Use professional pile pulling equipment, such as a pile puller or a hydraulic pile puller.

Fix the clamp or chuck of the pile pulling equipment to the top of the concrete pile.

Start the equipment and pull the concrete pile out of the soil by applying an upward pulling force.

During the removal process, attention should be paid to the protection of the surrounding soil and buildings to avoid unnecessary damage.

2-1. Crushing method

Applicable situation: when the diameter of the concrete pile is large, or there are important buildings and underground pipelines around, it is necessary to avoid excessive impact on the surrounding environment.

Operation method:

Use equipment such as a breaker hammer or impact drill.

Drill the equipment into the concrete pile or crush it along the pile body.

Break the concrete pile into small pieces or powder through continuous crushing operations.

Clean up the crushed concrete fragments to ensure the cleanliness and safety of the construction area.

2-2. Casing rotator pile extraction method

Applicable situation:It is especially suitable for bored piles with uneven pile diameters or prone to collapse. The full-rotation pile extraction method can effectively remove such piles by using its powerful downward pressure and rotation torque. It is suitable for situations where the construction site is limited and surrounding buildings and underground pipelines need to be protected, or the pile extraction task needs to be completed quickly. In addition, the foundation of the site in the pile extraction area must be solid.

Operation method:

1) Segmental casing drilling

Casing pressing and drilling: Use the hydraulic cylinder of the drilling rig to press the segmental casing into the soil section by section, and start the rotary device to rotate the casing to reduce the friction resistance between the casing and the soil, and use the drilling teeth at the end of the casing to cut the soil.

Verticality control: During the drilling process, use the horizontal monitoring system of the equipment to check the verticality of the casing, and make adjustments in time to ensure that the verticality of the casing meets the design requirements.

Hole cleaning and acceptance: After the hole is drilled to the design elevation, the hole cleaning operation is carried out, and the geological survey, supervision, and Party A units are invited to conduct acceptance to ensure that the hole quality meets the requirements.

2) Pile extraction operation

Gap filling and rotation: Use a plug to fill the gap between the pile body and the steel casing, and then start the rotary device of the full-rotation drilling rig to drive the steel casing to rotate to twist the pile body and loosen it.

Lifting out the pile body: After the pile body is loosened, weld the lock pipe and all the steel bars on the top of the pile firmly, put on the shoulder pole, and connect the crane hook through the steel shoulder pole. Then use the crane to lift the pile body.

3) Pulling out the casing and backfilling reinforcement

Pulling out the casing: After confirming that the concrete pile has been completely pulled out, start pulling out the steel casing. During the pulling out process, backfilling should be done while pulling out to ensure that the backfill material fills the hole and ensures the density of the backfill.

Backfilling reinforcement: The backfill material can be cement soil, concrete and other materials, which are determined according to the design requirements. The backfilling operation should be carried out simultaneously with the pulling out of the casing until the last section of the casing is pulled out and the backfill material is backfilled to the floor elevation.

3. Rotary Drill Removal Method

Applicable Situations: Applicable to concrete piles of various diameters and depths, especially when the pile body is long or part of the pile body needs to be retained.

Operation method:

Use a rotary drill to cut the concrete pile by rotating the kelly bar and drill bit.

During the cutting process, the cutting depth of the drill bit should be gradually deepened until the concrete pile is completely cut off.

Clean up the cut concrete fragments and perform subsequent treatment as needed.

4. Chemical Corrosion Method

Applicable Situations: Less used, mainly considered under specific conditions (such as strict environmental protection requirements, limited surrounding space, etc.).

Operation method:

Inject chemical corrosive agents into the concrete pile through drilling.

Corrosive agents react chemically with concrete, resulting in reduced pile strength.

At the appropriate time, use mechanical or manual methods to remove the corroded concrete piles.

It should be noted that the chemical corrosion method may cause pollution to the environment, so the relevant environmental protection laws and regulations and requirements should be fully understood before use.

5. Comprehensive method

In actual projects, it is often necessary to adopt a comprehensive method to remove old deep concrete piles according to specific circumstances. For example, you can first use the crushing method to crush part of the pile body, and then use the pile pulling method to pull out the remaining part; or first use the rotary drill removal method to cut off the pile body, and then carry out subsequent treatment.

6. Precautions

Safety protection: In the process of removing concrete piles, the safety protection of construction personnel should be done well to avoid accidental injuries.

Environmental protection: In the process of removal, effective measures should be taken to reduce pollution and damage to the surrounding environment. For example, use low-noise and low-vibration equipment; clean up construction garbage and waste in time; when constructing in sensitive areas, sound insulation and vibration isolation measures should be taken.

Cost control: When removing old deep concrete piles, cost factors should be fully considered. Reduce costs by reasonably selecting construction methods, optimizing construction processes, and improving construction efficiency.