What Are the Current Trenchless Rehabilitation Methods of Urban Drainage Pipes?

Ⅰ. Wide use of trenchless pipe rehabilitation

Trenchless pipe rehabilitation has been widely used in daily life. This trenchless rehabilitation uses convenient and scientific methods to rehabilitate the inside of the pipe without damaging the road. In recent years, the trenchless technology has also been continuously updated. New technology has been gradually used in pipe rehabilitation, bringing a more scientific and efficient construction experience.

Ⅱ. Methods of trenchless rehabilitation of urban drainage pipes

At present, there are three types of more advanced trenchless pipe rehabilitation technology, the first one is to use resin solidification method to form a new drainage pipe inside the pipe, such as CIPP, on-site solidification and other processes; the second one is to use small pipes to pass through large pipes, and insert small drainage pipes inside the original pipes to solve the urgent need, such as short pipe lining, U-shaped pipe dragging and other processes; the third one is to use spiral pipe to form a new pipe inside the original pipe by winding method, such as spiral winding method, etc.

1. CIPP rehabilitation, also known as the liner Inversion method, adopts the principle of resin heating or light solidification. The unformed resin is overturned inside the pipe by water pressure or air pressure, and then the water inside the pipe is heated to heat the resin inside the pipe to solidify and form a new pipe. It can repair a whole section of pipe at the same time, and it can also repair local leaking points at the joints.

Before using this method to repair the drainage pipe, the drainage pipe should be sealed and wash-cleaned, and the leaking point on the inner wall of the pipe should be plugged by methods such as grease injection and grouting. After there is no water leakage inside the pipe, the semi-finished resin pipe processed in the factory is transported to the site, the pipe is overturned inside the original pipe by water pressure, and then the principle of circulating heating is used to heat the water inside the pipe to about 70 degrees and to 90 degrees for a period of time, which is enough to solidify and cool the resin, and handle the connection between the pipe and the inspection well.

2. Trenchless pipe lining, that is, the short pipe is welded on site while being dragged into the old pipe, and finally the gap between the new and old pipe is filled with grouting. This rehabilitation method is usually applicable when the water flow requirement is reduced.

3. Spiral lining is mainly formed by spiral winding and the strip inside the old pipe is continuously advanced through the pressing bayonet to form a new pipe. The pipe can be operated normally with water flowing and the water depth of 30%.

The spiral pipe method is currently widely used. After the pipe is repaired, the inner wall is smooth, and the water passing capacity is better than that of the concrete pipe before the rehabilitation. Moreover, the material occupies a smaller area and is suitable for long-distance pipe rehabilitation.

4.Partial rehabilitation, as a more mature technology at present is under the guidance of the endoscopic camera system car, using stainless steel collars to jam the leaking places such as pipe joints, and grout inside to restore the function of the pipe. This method is suitable for pipes with problems only in partial interfaces or places because in order to save costs, this specific place is specially rehabilitated.