Principles of Concrete Drainage Pipe Damage

Concrete drainage pipes have excellent load-bearing capacity and have been widely used in the construction of municipal drainage systems. However, due to the continuous changes in residents' lifestyle and dietary structure, the increase in organic matter content of urban wastewater, and the unreasonable methods and structures of wastewater drainage facilities, harmful gases produced under microbial action lead to the corrosion and neutralization of the concrete. As time goes on, this damage becomes more severe, resulting in the corrosion of the cement pipe walls to the point of peeling off completely, the soil layer above the pipe walls gradually collapsing due to the loss of support, and the fallen soil and rocks accumulating in the pipes. In severe cases, this can cause pipe blockages and even ground subsidence, posing a threat to the personal safety of others.

Non-invasive pipe bursting repair technology application

In light of the drawbacks of traditional excavation and repair methods, such as road disruption and traffic impact during the replacement of drainage pipelines, our technical team, combining on-site conditions and past construction experience, has developed a new non-excavation pipeline construction technique—Fracture Pipe Method. The Fracture Pipe Method is a non-excavation technique that uses parent-child pipe sealing locks to connect and expand the pipe for repair. This method is currently economical and rational, as it performs work on adjacent inspection points without excavating the road surface. It uses the pipeline to be repaired as a carrier, transporting short sections of specially machined polyethylene (PE) pipes to the manhole, and completing the connection between the short pipes through impact fitting. Simultaneously, a silent hydraulic traction device is used to pull it to the required position, replacing the original reinforced cement pipeline with PE water supply solid-wall pipes, thereby repairing the damaged pipeline.

Construction site for the non-trenching pipe bursting repair process is similar to the images shown below.

2. The pipe material used in the pipe replacement process by the split pipe method is widely applied in water supply and gas sectors. Made of polyethylene plastic, it is more durable than cement, clay pipes, and other drainage pipes due to its good chemical stability. Moreover, the inner wall of the replaced pipe is smoother, significantly reducing the accumulation of debris.

The internal photo of the PE plastic pipe after displacement by the split-tube method, after two years of use, is as shown below. From the image, it can be observed that even after two years of use, there is only a small amount of sediment at the bottom of the pipe. This is sufficient to demonstrate the superior properties of PE plastic pipes over conventional cement pipes.

3. The pipe connection method used in the construction technology of the split tube method employs a simpler parent-child lock buckle process than the hot melt method. The design of the parent-child lock buckle, along with the method of tenon lock buckle, achieves the connection of PE short sections through impact, effectively preventing the detachment of pipe ends and facilitating the connection between short pipe sections. The structure of the tenon lock buckle is shown in the figure below.

4. Design Features of Sub-Mother Lock Coupling Technology: The combination of interface sealing groove anti-seepage design with mortise lock coupling ensures that after the short pipe section is assembled, it cannot be easily disassembled while meeting the anti-seepage design requirements. Additionally, it eliminates the need for welding processes and avoids the excavation of large working surfaces. Our company owns multiple advanced CNC machining equipment, capable of quickly meeting the large-scale material requirements for construction. Below is a daily overview of our company's PE plastic short section processing.

5. The pipe bursting construction method allows for the replacement of old pipes with new ones, either with the same diameter or an enlarged diameter, based on the existing pipeline. The image below shows a before-and-after comparison of the wastewater pipeline renovation performed by our company. We employed the pipe bursting technique to increase the diameter of the original DN200mm earthenware drainage pipe to 250mm and replaced it with a PE plastic water supply pipe.

6. Short construction period, strong daily repair capacity. For instance, our company has remodeled a sewage pipeline at a primary school in Haidian, Beijing, where the pipeline is 207 meters long with various structures above the ground, resulting in high excavation costs. We employed the pipe bursting construction method, replacing the original DN300mm cement pipes with DN315mm PE water supply pipes, completed in total of fifteen days.

For drainage pipes made of materials such as double-wall corrugated pipes and PVC, if the pipe replacement process employs the split tube method, such as with HDPE double-wall corrugated pipes, due to their soft nature, this should be determined on a case-by-case basis. Generally...

Short well spacing can be replaced with equal diameter, while long spacing requires reduction in diameter using the same process.

The following image shows the comparison of the double-wall corrugated pipe before and after replacement:

The pipeline shown in the above image has an original length of 23 meters and is buried at a depth of 2.5 meters. It was initially a reinforced concrete pipe with a diameter of dn200mm. Due to severe corrosion over time, the pipeline developed ground subsidence issues. The property management department of the community then conducted manual excavation, replacing the 200mm diameter concrete pipe with a dn300 double-walled corrugated pipe. Later, due to insufficient rigidity in the double-walled corrugated pipe and inadequate backfilling in some areas, the soil layer sank, causing the corrugated pipes to come into contact with each other. This resulted in the pipeline being unable to function properly. The local contact situation is shown in the image below:

Our company employs the split-tube construction technique, replacing the already bonded inner and outer walls of the double-wall corrugated pipe with a more robust and durable PE water supply pipe. We have been specializing in non-invasive repair construction for collapsed drainage pipelines for many years, and over the past few years, our business has expanded across the country.