What is the "piping" phenomenon of Dongting Lake's dam bursting? How to rescue it?

July 5 afternoon

Tuanbei Village, Tuanzhou Township, Huarong County, Yueyang City, Hunan Province

Tuanzhouwan Dongting Lake first line embankment

Pipe burst caused dam breach

What is piping?

How to rescue

Let's find out together

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What is piping?

Piping refers to water flowing through pores or cracks in the soil, forming a pipe-like water flow channel, causing soil particles to be carried away and forming cavities. When the cavities expand to a certain extent, the dam will collapse and form a breach.

What is the main cause of piping?

1. The soil gradation of the foundation of dams and sluices lacks some non-cohesive soil with intermediate particle sizes. When the water level of rivers or reservoirs rises and the seepage slope at the escape point is greater than the allowable value of the soil, the finer soil particles in the foundation soil are carried away by the seepage to form piping;

2. The foundation soil layer contains a strong permeable layer, and the soil layer covering the top is not heavy enough;

3. The project's anti-seepage or drainage (seepage) facilities are inefficient or damaged and ineffective.

After a pipe burst occurs, emergency rescue and protection should be carried out immediately. The rescue principle is to intercept and guide the seepage on the water surface, and to guide the seepage on the water surface. At the same time, emergency rescue measures of guiding and pressurizing the seepage should be taken at the pipe burst point to reduce the seepage pressure, prevent the seepage from bringing out fine particles, and leave a way out for the seepage water.

What are the emergency rescue methods for pipe burst?

Filter well

Use woven bags or sacks filled with soil to build a well enclosure at the pipe burst mouth. The bottom of the well wall is in close contact with the ground. The well is filled with sand, gravel or firewood filter materials in layers according to the three-layer anti-filtration requirements. Install a drainage pipe at the wellhead to divert the seeping clean water to prevent overflow and cause damage to the well wall.

Water storage back pressure (commonly known as water basin)

Use earth bags to build a well around the pipe burst, the well wall is watertight, and no filter material is filled in the well. If there are many pipe burst points and the area is large, slightly expand the area near the dangerous outlet to build an earth embankment to form a water reservoir (water basin) to prevent the seepage water from flowing away, and use the seepage water to slowly raise the water level in the well (pool), reduce the front and back water level difference, and thus prevent the dangerous situation from worsening.

Water filtration and infiltration platform

When there are multiple and connected piping points, coarse sand, stone chips and gravel can be spread on the surface in layers, with finer at the bottom and coarser at the top, with each layer about 20 cm thick, and finally pressed with stones or earth bags to form a pressure seepage platform. If there is a lack of sand and stone materials around the dangerous area, straw or branches can be used to make rows, and then pressed with stones or sand bags. This method is suitable for dealing with dangerous situations with a large number of piping and a large range.