The microtunnelling technology does not require opening surfaces along the entire tunnelling of utility lines. Microtunnelling enables to perform utility line tunnelling tasks in most difficult conditions, in which previously it was not possible to do anything without using special methods (water level reduction, freezing, etc).


Microtunnelling is increasingly more used in large cities as a trenchless collector construction method. The important characteristic of the technology is the fact that microtunnelling is very precise and its trajectory can be controlled constantly.


The company SMALGER performs microtunnelling complex works with microtunnelling machinery AVN from the company “Herrenknecht”, which enables to install fibreglass plastic, polymer concrete, ceramic, reinforced concrete and steel pipes with an external diameter of 400-1400 mm, at a distance of up to 250 m without wells in-between.

 

Main diagram of microtunneling technology

 

Microtunneling technology

Wells are built from the ground: start and reception wells, the distance between them can be 50…250 m, the depth up to 10 m and more.


According to the plan, the wells can be either round or square, with side measurements about 5 m.


The working organ of the microtunnelling complex AVN performs tunnelling from the start well when there is excessive water pressure in lava. Feeding water to the AVN intersection working organ and pumping out the pulp formed takes place by using pumps, which are installed on the surface near the start well. Into the start well also single links of pipes are fed; they are pressed into the soil with jacks, which enables to perform horizontal tunnelling of the collector. The preciseness of tunnelling is adjusted with the help of a laser ray from the control station above ground. All technological and control functions in the case of microtunnelling are performed with the help of a computer. The processed pulp is fed into the sludge holder with pumps, water from which is repeatedly used in tunnelling, while the solid sludge is transported to a refuse disposal site as it collects.


Microtunnelling with the AVN complex is performed in a semiautomatic mode, controlled by operators located in the control block.