The whole processing of using tremie pipes in grouting projects

Underwater concrete pouring, also known as conduit concrete, is a method of pouring concrete through a vertical pipe, relying on the concrete's own weight. It is suitable for pouring surrounding grout, caisson foundation, underground continuous wall, pile foundation and other underwater or underground projects. Concrete flows out slowly from the lower end of the pipe and expands to the surrounding areas without being disturbed by the surrounding water flow, thus ensuring quality.

There are many types of tremie pipes, including dozens of products of different sizes. Each product has different wall thicknesses and different joint forms. Each different parameter will result in different prices. Then how to match suitable specification for your projects?

In simple terms, the model of the pipe is selected according to the pile diameter, and the thickness of the pipe wall is selected according to the pile depth.

Before using the tremie pipes, let's know how many accessories for choose.

- Large hopper: We call hoppers with a capacity of 1 cubic meter or more as large hoppers. The choice of the number of large hoppers is generally determined by the diameter of the pile. The first pouring is referred to as the bottom seal. The concrete required for the bottom seal generally requires the catheter to be buried about 1.5 meters away.

- Wellhead frame: The wellhead frame is generally mounted on a steel protective barrel, and the catheter is fixed for pouring through the middle cover. Generally, there are 2 meters, 2.5 meters, 3 meters, etc., which are all determined by the diameter of the pile.

- Small hopper: Under normal circumstances, after the pouring construction completes the bottom seal operation, the catheter needs to be continuously dismantled and installed, and the labor time and labor intensity of the construction are increased. The small hopper is light in weight, and the discharge port can be directly inserted into the pipe body, which will be more convenient.

- Hole cleaning head: Its main function is to serve as a hole cleaning slurry return and sealing experiment.

The inner wall of the pipes must be kept smooth and round, the interface must be tight, and trial assembly and pressure testing must be carried out before using.

The axis deviation of the pipes after assembly shall not exceed 0.5% of the drilling depth and shall not exceed 10cm. The test water pressure shall be 1.5 times the hydrostatic pressure at the bottom of the hole.

How to operate the testing?

Preparing:

- Check the appearance of the tremie pipe to ensure there are no cracks, deformations or other damage.

- Confirm whether the connection part of the tremie pipe is well sealed to prevent slurry leakage.

- Prepare necessary tools and materials, such as pressure gauge, water source, connecting pipes, etc.

Processing:

- Install the tremie pipe into the test device and ensure that it is firmly connected and well sealed.

- Slowly fill the tremie pipe with water until the predetermined test pressure is reached.

- After reaching the test pressure, maintain the pressure for a period of time (usually a few minutes) and observe whether the tremie pipe has any abnormalities such as leakage or deformation.

- If leakage or abnormality is found, stop the test immediately, check and repair the problem and then retest

Record and analyze:

- During the pressure test, closely observe the changes in the pressure gauge and keep detailed records.

- Record the time, location, participants, pressure, test results, problems found and how they were handled

Note:

- The test pressure should not exceed the design tolerance of the tremie pipe to avoid damage.

- During the test, the safety of the test environment should be ensured, warning signs should be set up, and personnel should be kept at a safe distance.

- If any problems are found in the tremie pipe, the test should be stopped in time, and inspection and treatment should be carried out.

After testing, we ‘ll install the tremie pipe. When the conduit is hoisted into the hole, place the rubber circle or rubber pad neatly and tightly to ensure good sealing.

The first purpose of tremie pipe: hole cleaning

Before pouring underwater concrete, check the thickness of the sediment again. When the original thickness of the friction sediment is greater than 20cm or the thickness of the pile diameter sediment is greater than 5cm, use the catheter to clean the hole for the second time. The mud specific gravity, sand content and viscosity after the second hole cleaning are qualified. Immediately pour underwater concrete after the hole cleaning is qualified.

The second purpose of the tremie pipe: pouring concrete

All pile foundation concrete is mixed centrally, transported by tank trucks and continuously injected through ducts. It is strictly forbidden to have long intervals between tests on-site by test personnel to check whether the slump, expansion and air content of the concrete meet the design requirements, and to make standard curing specimens in accordance with regulations.

The first pouring adopts the method of large hopper and isolation ball. The size of the large hopper is determined according to the calculation of the first volume. During the pouring process, the buried depth of the conduit in the concrete is controlled between 2-6m. The position of the concrete surface in the hole is measured in time and the buried depth of the conduit is adjusted. The pouring record is filled in as required. The pouring height is controlled to be 1m higher than the designed height of the pile top to ensure the quality of the concrete on the pile top.

After the underwater concrete pouring is completed, the remaining pipes and steel casings are slowly pulled out by crane, and personnel are arranged to clean them in time for reuse.