What issues deserve attention during pipe jacking construction?

Trenchless engineering technology has completely solved the problems of damage to urban buildings and congestion of road traffic during pipeline burial construction, highlighting its advantages in stabilizing the soil layer and protecting the environment. This is very important for cities with heavy traffic, dense population, numerous ground buildings, and complex underground pipelines. It will create a clean, comfortable and beautiful environment for the city.

Trenchless technology is a term that has just begun to be used frequently. It involves the use of less excavation, that is, working wells and receiving wells need to be excavated, and no excavation, that is, no pipe excavation technology to lay or replace underground pipelines. The pipe diameter is DN800-4500. Push the pipe to be jacked into the receiving well through the working well. The pipe in a working well can travel more than 1,500 meters underground, and can also travel in a curve to bypass some underground pipelines or obstacles.

Its technical point is to correct the deviation of the pipe extending underground. It is especially suitable for trenchless laying of large and medium-sized pipes. It has comprehensive functions of economy, efficiency and environmental protection. The advantages of this technology are: no ground excavation; no demolition, no damage to ground buildings; no damage to the environment; no impact on the step deformation of pipelines; time saving, high efficiency, safety, and low overall cost.

This technology is widely used in the non-excavation laying of various pipelines such as urban underground water supply and drainage pipelines, natural gas and oil pipelines, and communication cables in economically developed coastal areas of my country. It can cross roads, railways, bridges, mountains, rivers, straits and any buildings on the ground. Using this technology for construction can save a lot of land acquisition and demolition costs, reduce environmental pollution and road blockage, and has significant economic and social benefits.

During the pipe jacking construction process of concrete precast components, the following noteworthy problems are often encountered:

1. Engineering geology and hydrogeology conditions frequently change the soil layer along the pipeline, so it is necessary to understand the changes in the soil layer before pipe jacking construction: In addition, the backfilled soil section needs to be reinforced in advance to prevent excessive surface subsidence after pipe jacking construction.

2. Detection and protection of toxic gases. The stratum during pipe jacking construction generally passes through the silt layer. Decaying animals and plants will form toxic gas aggregates underground, endangering the health and lives of construction workers. Therefore, when there are people operating in the pipe jacking, it is necessary to regularly monitor the content of toxic gases in the pipe and use ventilation devices to solve the problem.

3. Advance detection of underground pipelines. Although advanced pipe jacking equipment has the ability to detect pipelines not far from the forward route during construction, it is still worthwhile to identify underground pipelines on the ground in advance. This is still necessary to ensure the safe operation of other pipelines such as communications, electricity, water supply, drainage, gas, etc., and to ensure the normal life of the public.

4. Exploration of the foundation when passing through the building. When jacking pipes under the building foundation, it is necessary to clarify the types of foundations encountered on the construction route. Underpinning and reinforcement measures can be taken for some foundation pipes before jacking.

5. The jacking calculation includes accurately calculating the jacking thrust, selecting the corresponding cylinder type and determining the distribution of relay rooms based on the calculation results; the second is the design of the working well, and proposing a reinforcement plan for the working well based on the calculated large jacking force.