A cost-effective alternative to conventional reinforced concrete monolithic chambers is the use of prefabricated wells in microtunelling. This will eliminate expensive earthworks and reinforcing and cementing works, as well as the keeping of proper groundwater table level.

A sunk well is placed in the excavation and through evenly digging inside of it, it gradually sinks down under its own weight.

The diameter of a sunk well depends on the needs in a given construction process and the pipes that are to be microtunelled:
• starting well: the diameter of ramming pipes, the number of connections and the size of the ramming frame
• end well: the size of the drilling head that needs to be excavated.

zapuszczone 2 zapuszczone 3 zapuszczone 4

 

Structurezapuszczone 8

Structural elements of the sunk well are: the bottom head, provisional sections and cover plate, made from C 35/45 class concrete.

The bottom head is fitted with a concrete blade, whilst the connections of structural elements are made with overlap with elastomer gaskets.

The setting of prefabricated chambers is supported with a concrete blade, suited to the type of ground, additionally supported with a steel blade in case of compact soil.

In case of deep shafts and high level of groundwater table, resulting in high uplift pressure, a heavy concrete plug must be completed below the well’s foundation.

Should the structural height of the bottom element be insufficient, there is the possibility of extending it, through the use of an additional well section.

 

 

 

 

 

studnie zapuszczane
średnica
nominalna
średnica
zewnętrzna
grubość
ścianki
wysokość masa objętość
mm mm mm mm` t/m m3 /m
3200 3700 250 3000 6,77 2,71
2500 2740 120 2850 2,47 0,99
2000 2400 200 2850 2,8 1,38
2000 2240 120 2850 1,96 0,8

 

Building Tipswpuszczone 2

The well’s setting is done mainly through sinking the element through even digging inside the concrete ring. This method can also be used when setting the well in the ground of high level of groundwater table, without the need to lower the groundwater table level. In such the case, after achieving the planned depth of the structure, make a hydrotechnical concrete plug of proper thickness at the bottom of the well. In case of the presence of groundwater of high uplift pressure, perform additional sealing works between the concrete plus and the concrete ring.

 

wpuszczone 3This method allows for reaching the depth of up to 10 meters. The bottom of the sunk well, made of the concrete plug, prevents the penetration of groundwater and further sinking down of the structure. This setting of the well is at the same time a footing, on which a machine for microtunelling or drilling can be positioned. Following the completion of the works and removal of the machine, the sunk well can be used as final well/chamber, after further reinforcing (invert channel, step irons, cover plate).

 

 

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