PROCEDURE FOR THE PRODUCTION OF AN INFRASTRUCTURE CHANNEL

A method for the production of an infrastructure channel

The invention relates to a method for producing an infrastructure channel consisting of at least two segments of a predetermined length.

Infrastructure channels are employed in particular in new building construction areas or large redevelopment projects in order to combine all supply and drainage lines in a single, preferably man-sized, sealed channel. Thanks to its spatial design, the supply and drainage lines can be directly and permanently monitored. Pipe leakage and cable emissions within a multi-utility duct of an infrastructure channel reach the sole of the building in liquid or semi-solid form or can leak out as a gas in the air filled space of the utility duct. Leaks in pipelines can be indicated by installed leakage warning systems, without excavation being necessary. Furthermore, replacing or installing new supply and drainage lines within the infrastructure channel can be done easily as access is possible via construction openings without excavation. In addition, not only the supply and drainage lines, but also the inside of the infrastructure channel can be inspected using a commercially available channel inspection camera system.

Separating the static parts of the infrastructure channel from the supply and drainage lines in the multi-utility duct provides a relatively high level of safety with respect to leakage resulting from infrastructure channel subsidence, with the protective function of a doublewalled pipe being exceeded by a development solution employing an infrastructure channel. Moreover, roots are unable to penetrate the supply and drainage lines through unsealed segment joints and crack damage.

DE 20113897 U1 makes known an infrastructure channel consisting of individual, singlepiece prefabricated segments that are combined to create a continuous channel. Each prefabricated segment is provided with a base plate, onto which two lateral walls are connected, which are connected to each other by means of vaulting at the top. The prefabricated segments are manufactured on a production line and combined on the construction site by means of seals on the front faces. In order to be able to transport the prefabricated segments without damage, at the least it is necessary to provide expensive reinforcing protection during transportation. Furthermore, producing a flat trench for accommodating the full surface of the prefabricated segment base plates requires a huge amount of work. In addition, sealing the facing ends of the adjacent prefabricated segments can only be achieved with great effort. Moreover, the factory-made prefabricated segments have the disadvantage that their length is very limited due to the constraints of production technology.

Furthermore, in practice channels are known that are not only prefabricated constructions, but also cast-in-situ concrete solutions provided with steel reinforcement, which have the disadvantage that in the event of cracking or efflorescence the reinforcing is exposed and can rust, initiating the complete destruction of the channels, e.g. due to the rupturing effect. In the event of fire the concrete pops off the steel reinforcement and the channel is subsequently destroyed.

In addition, DE 35 24 687 A1 makes known a method for the production of an in-situ concrete channel that avoids joints and the associated leakage points.

Finally, GB 2 360 472 A shows an in-situ concrete with polypropylene reinforcement.

The object of the invention is to provide a method of the kind mentioned at the outset that ensures the rapid and inexpensive production of an infrastructure channel.

In accordance with the invention, the object is fulfilled by pouring each segment in one piece on site using in-situ concrete or ready-mixed concrete, an inner shell is spanned with a drainage geotextile and the beginning and the end of the infrastructure channel is closed by means of wooden panels and/or a strip sheet curtain while the in-situ concrete is drying.

Each individual segment of the infrastructure channel is produced as a single piece on the construction site continuously from in-situ concrete or ready mixed concrete; in the present description the term "in-situ concrete" also encompasses ready mixed concrete.

The length of each segment being produced is dimensioned in each case such that the segment can be produced as one day's work, with the length being between 4m and 40m, preferably between 10m and 20m, preferentially 15m. Steel reinforcement is not necessary. The lack of steel reinforcement and the relatively large length of each segment and the relatively minimal preparation ensures that the infrastructure channel is produced quickly and cost effectively. In order to absorb the water expelled during compacting of the in-situ concrete and to provide it again to the in-situ concrete during its subsequent setting, provision is made for the drainage geotextile to span the inner formwork.

The steel inner formwork, a hinged steel shutter that can be moved into a concreting position and a driving position, is spanned by a plastic mesh that is firmly attached to the inner formwork by means of plastic rivets.

The reusable drainage geotextile, which is tightly spanned across the inner formwork in the concreting position, is attached to the plastic mesh. In addition, it makes sense to close the beginning of the infrastructure channel with wooden panels provided with a door and to close the end of each form of the segment being made with a strip sheet curtain in order to prevent any undesirable drafts of air within the infrastructure channel. The strip sheet curtain can be fastened onto the inner formwork, for instance at the end of the infrastructure channel. In addition, the wooden panels could be useful for securing a handling device, in particular a cableway crane, for moving parts on the construction site, in particular sheet insulation.

Preferably, an expansion joint waterstop is poured in between two adjacent segments.

The expansion joint waterstop comprises two sealing strips connected to each other by means of a central tube, with each sealing strip corresponding to one end of one segment.

For reasons of functionality, the expansion joint waterstop with sealing parts is inserted into the end surface of each segment. For this purpose an end shutter is employed, which is provided with slits for the expansion joint waterstop, which is connected securely to the segments after the in-situ concrete has set, virtually ruling out any leakage. Furthermore, provision is made for a component consisting of foamed polymer, in particular polystyrene, that ensures the functionality of the expansion joint waterstop.

Preferably, an atmospheric humidifier to cure the in-situ concrete is set up inside the segment after the formwork has been removed from it. In order to ensure the efficacy of the atmospheric humidifier, for reasons of functionality a sheet wall is erected inside the infrastructure channel as a function of the number of segments involved. The sheet wall can be developed in portable form and be moved in accordance with construction progress in order for curing with the atmospheric humidifier to be completed in about three sections for each segment.

In order to remove the formwork of the segment relatively early despite the high proportion of fly ash in the in-situ concrete, thermally insulated external formwork is preferred.

According to another embodiment, the segments are covered by at least one air bubble film after the removal of the formwork. The sprinkler hose is developed such that the setting in-situ concrete is prevented from eroding, which is why it is preferably provided with micro-openings.

In a further embodiment, a controllable heating system is operated inside the internal formwork. The heating, that can comprise one or a plurality of gas burners, is especially required when the ambient temperature is low and can be controlled by the concrete maturity computer by means of the temperature measurement data.

The reinforcement of in-situ concrete for the production of an infrastructure channel is constituted by artificial fibres, in particular polypropylene fibres, with the artificial fibres being mixed into the in-situ concrete and the in-situ concrete has a short stiffening time and in particular a green strength of 6 N/mm2. This allows the formwork to be removed quickly.

Furthermore, the in-situ concrete comprises a disproportionately large proportion of fly ash. Depending on the external temperature, the proportion of fly ash can be larger than the proportion of cement. Such a formula is not permitted under the German standard for reinforced concrete. However, as the individual segments of the infrastructure channel are not provided with steel, this standard is meaningless in the present case. The high proportion of fly ash offers not only economic, but also ecological benefits. However, in particular heat generation is less than with standard formulas, with the risk of shrinkage cracks developing.

In the case of one infrastructure channel, an upper vault of a segment is provided with a cover, dimensioned in such a manner that tubing, in particular a high-voltage conduit, can be introduced into the inside. The cover must be provided with relatively large dimensions so that the tubing, which is generally rigid, can be introduced into the centre of the infrastructure channel. The opening for accommodating the cover, which can be opened for subsequent activities in particular, is produced by means of a conical cut out in the inner formwork and a cover provided with an outer contour corresponding to the opening is manufactured accordingly in a prefabricated mould to fit perfectly.

Preferably, at least one of the side walls is provided with at least one corbel to support the conduit. The corbel can for instance be fastened by means of a tie rod. The corbel, which has for instance an L-shaped or Z-shaped cross-section, ensures a reliable support for the conduit and allows the ends of two pipes being connected to be welded together.

Furthermore, the corbel is dimensioned to support rollers for displacing the conduit. For reasons of functionality, the corbel consists of fibrous cement.

It goes without saying that the characteristics mentioned above and those to be discussed below can be utilised in combinations other than those indicated in each specific case.

The scope of the invention is only defined by the claims.

The invention is described in more detail below on the basis of one embodiment with reference to the corresponding drawings. In the drawing:

Fig. 1 shows a longitudinal view through an infrastructure channel produced using the method in accordance with the invention, with a one complete segment and two outlined segments,

Fig. 2 shows a cross-section through a segment of the infrastructure channel in accordance with Fig. 1,

Fig. 3 shows a representation of the infrastructure channel in perspective in accordance with Fig. 1,

Fig. 4 shows a front view of the infrastructure channel in accordance with Fig. 3, and Fig. 5 shows a magnified representation of corbels for the infrastructure channel.

The infrastructure channel 1 consists of a large number of segments 2, with the facing ends 3 of each segment abutting the said facing ends of the adjacent segments in a sealed manner. Provision is made for an expansion joint waterstop 5 to seal the joint 4 existing between two facing ends 3, with said waterstop comprising a central hose 6, with sealing components 7, 8 connected on both sides of it that abut against the segment 2 in each case.

Each segment 2 of the infrastructure channel 1 is produced continuously on the construction site from in-situ concrete 9 by means of a one-piece construction method 9.To do this, a predominantly flat and compressed ground surface is created in an excavation pit. The length of each segment 2 to be produced is dimensioned such that it can be completed in a single day's work.

To produce a segment 2, internal formwork 11 without a floor, consisting of sheet metal and provided with hinges 12, is installed first, with the hinges 12 serving to swing the sections of internal formwork 11 inward after the in-situ concrete 9 has cured. The concreting process is performed in linked partial steps, with a sole 10 with wall stubs being poured first on the flat ground surface. There is a short waiting period before the side walls 16 and a vault 17 are concreted in order for the in-situ concrete 9 of the sole 10 to set.

A drainage geotextile 15 is spanned over the internal formwork 11 that absorbs the water escaping from the settling in-situ concrete and then makes it available to it again during subsequent curing of the in-situ concrete 9. After the drainage geotextile 15 has been installed, a thermally insulating outer shell 19 is installed for the walls 16 and the vault 17.

An end shutter with slits for the expansion joint waterstop 5 is employed at each facing end. After the segment 2 is completed and the in-situ concrete 9 has set, the inner formwork 11 is folded together and then drawn out of the finished segment 2 in the direction of the arrow 18. The segment 2 is now closed on the entry side by means of wooden panels 20 provided with a door.

With the dismantling of the outer shell 19, sheets of air bubble film are pulled continuously with the progress of dismantling by means of a cableway crane 21 over the segment 2, with a frame 22 attached at the beginning of the infrastructure channel 1 and another frame 23 attached at its end, being displaced in accordance with construction progress.

The next segment 2 of the infrastructure channel 1 is then produced in the same manner, until the entire length of the infrastructure channel 1 is completed. The infrastructure channel 1 forms an accessible shell in which supply and drainage lines of any desired diameter can be laid. A reversal of or repair to the supply and drainage lines is possible at any time without excavations as manholes are arranged along the infrastructure channel 1 at least at intervals.

In order on the one hand to produce the segment 2 of the infrastructure channel 1 in one piece and on the other to do so without a loss of quality, in particular with respect to the formation of cracks, a formula for the in-situ concrete 9 is required that sets quickly, ensures a high green strength of around 6 N/mm2 and allows slow continuing curing with low hydration heat. Reinforcement 13 in the form of artificial fibres 14 is added to the in-situ concrete 9 in order to ensure special resilience of the in-situ concrete 9, in particular with tension and stress cracks being prevented and early, impact, shock and abrasion strength being increased.

Provision is made for corbels 25 to be arranged one above the other on one of the side walls 26 of the infrastructure channel 1 to support a conduit 24, with the corbels 25 developed in such a way that on the one hand they hold the conduit 24 securely, and on the other not only allow the conduit 24 to be welded to another conduit 24 at their facing ends, but also to provide a support for rollers for displacing the conduit 24.