Microtunneling technology (pipe laying)
Microtunneling is a technology of trenchless laying of underground communications, which eliminates the need for complex works related to traditional technologies. In contrast to the method of conducting works in an open way, it does not require dissection of the surface along the entire route of the laying of communications, which inevitably entails the closure of traffic and pedestrian traffic, cutting down of gardens and parks and other negative effects.
• Earth movement is minimized.
• Low impact on residents of nearby areas and the environment
• It is not necessary to lower the level of groundwater
• Minimal negative impact on traffic
• The laying depth is practically unlimited
In order to carry out the laying of communications, two shafts are sufficient: the starting and receiving shafts, the depth of which corresponds to the depth of the laying. A powerful jacking station is installed in the starting shaft, into which the pedestrian shield is installed. With the help of jacks, the shield is driven into the soil along its length, after which a microtunneling pipe is installed in the jacking station and the process is repeated. By building up the pipeline with separate pipes, a further passage is made to the exit of the shield into the receiving shaft. After that, the shield is dismantled, and the pipes remain in the ground.
When using intermediate jacking stations, the distance between the starting and receiving shafts can be more than 400 m. In this way, a collector with a diameter of 300 mm to 4.5 m can be laid. The accuracy of the passage is carried out by a computer control system using a laser shield guidance system.
Microtunneling technology allows laying pipelines in any soil class – from unstable loams and water-bearing sands to bedrock. Depending on the class of soil, the appropriate cutting body is selected, which allows to achieve optimal speed and parameters of passage.
The advanced complex control system ensures drilling accuracy that meets the highest requirements and allows you to monitor at any moment the indicators that fully characterize the position of the drilling shield, its movement parameters, as well as the operation parameters of its main nodes and mechanisms.
The complexes are built according to the modular principle, which allows you to transfer them from one object to another and to shorten the installation time of the equipment as much as possible.
Soil development is carried out with a cutting head. From the sedimentation tank located on the surface, water is fed through the water supply pipeline by a feed pump into the subsurface area, where it mixes with the developed soil, and then by a transport pump through the return water supply pipeline into the sedimentation tank. In the settling tank, the soil settles, after which the water is used again in the technological process, and the settled soil is removed. The tunnel shield has a controlled head, which allows you to change the direction of movement and lay pipelines both in a straight line and along curves.
The tightness of the pipeline is ensured by rubber sealing rings located on the sleeve part of the pipe. A special plywood gasket protects pipe joints from damage when traveling along curved paths.
The wide application of this method allows to increase the reliability of laying pipelines, save money, shorten the construction period and, importantly, does not harm the environment.
Microtunneling technology (tubing)
Shield penetration should be used: when laying cases of gas pipelines and oil pipelines used for electric cables; during the construction of urban underground communications; during the construction of crossing areas of land with high humidity; during the construction of railway crossings, airstrips and highways; when laying drainage structures to objects located in the center of the reservoir. Shield penetration is used when installing a collector with a diameter from 300 mm to 4.5 m.
The design of the shield, which consists of a cutting part, a system of jacks designed to push the shield into the ground, and a tail part, which allows for the installation of prefab treatment under cover. The jacks rest against the mounted tunnel finish and allow the direction of the tunnel to be adjusted. Removal of soil from the face is carried out with the help of belt conveyors, and it is lifted to the surface in buckets or trolleys. Immediately after the arrangement of the next treatment ring, without allowing the rock to settle, cement mortar is injected into the space between the treatment and the rock.