Hydraulic and Static Pipe Bursting
Hydraulic pipe bursting has been used in the Federal Republic of Germany in the past few years, for instance, under the designation KM- Berstlining [FI-KMG] (licensed under the patented IPD process of International Pipe Drilling (IPD) Ltd., European Patent No. 83303401 [FI-IPD]) and the pipe bursting process of Brochier Bau GmbH [FI-Terrab]. In both cases, hydraulically acting bursting bodies were utilised. In contrast to this, static bursting bodies without movable parts are mostly used today, e.g. in the Grundoburst process [FI-Tracta].
In the KM Berstlining process the pipe bursting body and new piping are discontinuously pulled through the defective sewer by a hydraulically operated cable winch placed above the target manhole.
The characteristic of this process is the hydraulically driven, statically working, widening mechanism with a 3-part bursting body (Image 18.104.22.168.3.3-1). The two front coned parts that are connected to each other and to a third part by links, each possess plates whose individual elements can be moved radially whereby the outer diameter of the point of the first one is some centimetres smaller than the inner diameter of the sewer to be replaced. This conicity permits the pulling-in of the bursting body by a certain distance into the sewer to be replaced. The third or rearmost part consists of a smooth steel cylinder whose outer diameter corresponds to that of the new pipe to be pulled-in and is thus larger than the inner diameter of the defective sewer.
After pulling the bursting body into the sewer to be replaced until it sits tight, the widening mechanism is operated, whereby the individual elements of the plates are pressed radially outwards with a pressure of up to 230 bar [Tucke87]. This causes the bursting of the old sewer with simultaneous displacement of the broken pipe pieces into the surrounding soil. Then the first product pipe is coupled in a tension resistant manner to the bursting body and is arrested by a clamping chain as well as a steel plate adapted to the size of the pipes and which is also fastened to the chain (Image 22.214.171.124.3.3-2). After the pipe bursting process, the widening mechanism is retracted so that the coned form of the first device part returns to its original condition. The bursting body can now be pulled forward, together with the coupled pipe, with a force up to 150 kN by a further length. The working steps are repeated in the new position. As soon as a pipe sector has been completely pulled-in, a new pipe is lowered into the manhole and connected to the one already installed. After successful replacement of the defective section of the sewer, the bursting body is removed from the target manhole (Image 126.96.36.199.3.3-3).
For this process the existing laterals must be cut off using the open cut method before beginning the work and after completion be reconnected again (Image 188.8.131.52.3.3-12).
With the aid of the KM Berstlining process there can presently be replaced sewers of brittle materials, e.g. vitrified clay or concrete from DN 200 to DN 400 without cross sectional reduction. Not suitable are steel, reinforced concrete, asbestos cement or GRP pipes [FI-KMG].
The expPRESS process developed in Sweden (Image 184.108.40.206.3.3-4) (Video 220.127.116.11.3.3-1) (Image 18.104.22.168.3.3-5) (Image 22.214.171.124.3.3-6) (Image 126.96.36.199.3.3-7) (Image 188.8.131.52.3.3-8) can be utilised in four machine versions in the nominal size range DN 180 to DN 900 and can also be used with larger pipes with additional equipment [FI-Entre] [Jürge90].
The process differs from those mentioned above in that the bursting body and continuous pipe are driven with the aid of a jacking installation without the assistance of a cable winch and that all the working steps in the sewer are monitored by a sewer camera. There is further the possibility, as a preparatory measure for the lining with prefabricated pipes (Abschnitt 184.108.40.206.1), of re-forming localised cracked and deformed pipes as well as repairing positional deviations.
A special development of the hydraulic pipe bursting process, of which there are no reports on practical testing, is the two-phase Magnaline process. It includes the following working steps (Image 220.127.116.11.3.3-9) [FI-Haywa].
- Pulling-in a pipeline consisting of individually abutted and longitudinally split thin-walled steel sleeves (Abschnitt 18.104.22.168.3) whose ends overlap each other.
- Prising open the steel sleeves and at the same time bursting the sewer with the bursting body.
- Inserting the product pipe (liner) in accordance with the pull-in or push process (Abschnitt 22.214.171.124.2).
- Grouting the annular space between steel sleeve and product pipe (Abschnitt 126.96.36.199.1).
In the Grundoburst process [FI-Tracta], the required forces for bursting, displacement and pipe pulling are applied by means of a tension and compression resistant ladder-type rod arrangement.
First the hydraulically driven bursting carriage is mounted in the starting excavation and clamped. Then the rod arrangement with the front-mounted guide is pushed through the vitrified clay, concrete (reinforced or not), grey cast iron, fibre cement (asbestos cement), PVC, steel or ductile cast iron old pipe. The connections of the ladder-type rod arrangement elements are achieved by means of clip-in quick couplings that can be opened and locked by swinging through 90°. In the target excavation, the guide is replaced with a bursting tool (bursting head with knives, roller cutting knives). The new, preferably HD-PE pipe, is fastened via a tension nipple to the bursting tool. When pulling back the rod arrangement in the direction of the starting excavation, the old pipe is burst by the bursting tool and the fragments are displaced into the surrounding soil by the expansion cone placed at the rear of the bursting tool. In this way the profile is expanded for the new pipe of the same or larger diameter (Image 188.8.131.52.3.3-10) (Image 184.108.40.206.3.3-11) (Image 220.127.116.11.3.3-12) (Image 18.104.22.168.3.3-13) (Image 22.214.171.124.3.3-14) (Image 126.96.36.199.3.3-15) (Image 188.8.131.52.3.3-16) (Image 184.108.40.206.3.3-17).
The utilisation of the static or hydraulic pipe bursting process under groundwater level without help measures is not possible. The ability to overcome obstacles and positional deviations is only possible to a limited extent according to [Zimme88], as static or hydraulic pipe bursting, when compared to the pneumatic process, only has a limited disintegrating energy in the drive direction.