|
|
(Image: Peeling off the protective coat of an Egeplast Saftey-Line coated pipe (SLM) [FI-Egepla]) (Image: Preparing the welding seam (left: removing the welding bead, right: bandaging the welded seam with a GRP bandage) [FI-Egepla]) Because of the additional outer coat, special cover sleeves are necessary for butt welding. In the region of the welding seam and the connections, it is necessary to peel off a sufficient width of the protective coat. (Image: … |
|
|
(Image: Application of double-walled pipe systems) (Image: Double-walled pipe system [Jürge05]) Damage to the product pipeline and loading by point or line loads is preventable through the implementation of a 2-phase installation. This process involves using a bursting unit to first install a casing pipeline into which the product pipeline is placed as part of the second working step. |
|
|
(Image: Lubrication of the new pipeline and fixing of the pipe fragments of the replaced pipe with a clay cement suspension) During the pipe bursting process the broken pieces of the old pipeline are fixed into place by grouting the annular space, formed by the bursting head, between the new pipeline and the cavity (also called the overcut) with a clay cement suspension [FI-Tracta] [Miege90] [Falk95b]. This procedure is also referred to as annular … |
|
|
(Image: Plus/Minus Icon) Advantages of annular space grouting:
(Image: Bursting process in combination with an annular space grouting [FI-Tracta] - Pipe piece removed showing clay cement and adhering fragments … |
|
|
May 27, 2019 |
|
|
May 27, 2019 Question: Upon which factors is the required bursting force dependant? 1st Factor (Image: Fragezeichen) 2nd Factor (Image: Fragezeichen) 3rd Factor (Image: Fragezeichen) |
|
|
May 27, 2019 The required bursting force is dependant on: 1. Breaking resistance of the old pipeline 2. Displacement capability of the soil in the embedment 3. Amount of expansion (Image: Breaking resistance) (Image: Displacement capability) (Image: Amount of expansion) |
|
|
(Image: Breaking resistance) The breaking resistance of the old pipeline is established by the:
|
|
|
(Image: Displacement capability) The displacement capability of the soil is established mostly by its density. Main influencing factors include the:
|
|
|
(Image: Amount of expansion) The amount of expansion corresponds to the radius of the expansion minus the internal radius of the old pipeline. The overcut (i.e. radius of expansion minus external radius of the new pipeline) should be as small as possible in order to minimize the movement of the old pipeline fragments. (Image: Amount of expansion and overcut) |
|
|
In determining the amount of expansion, the following questions must be answered while taking into account the existing soil conditions:
In order to prevent heaving or settling at the surface, a minimum pipeline depth of cover of 10 x the amount of expansion has proven to be … |
|
|
According to DWA-M 143-15 [DWAM143-15:2005], a buffer between parallel pipelines of at least three times the amount of expansion (minimum 40 cm) has proven to be effective for cohesive soils. (Image: Fragezeichen) Example calculation for the amount of expansion in cohesive soils: Diameter of the old pipeline: DN 250 Calculation according to DWA-M 143-15: 3 x (340 mm -– 250 … |
|
|
For non-cohesive and/or stony soils special considerations apply which concern the diameter and the material of the neighbouring pipelines. For pipe materials < DN 200 that are brittle and easy to break, the minimum spacing should be at least 5 times the amount of expansion. For nominal sizes > DN 200, the spacing should not be less than 1.0 m. (Image: Fragezeichen) Example calculation for the amount of expansion in non-cohesive soils: Neighbouring … |
|
|
For non-cohesive and/or stony soils special considerations apply which concern the diameter and the material of the neighbouring pipelines. For pipe materials < DN 200 that are brittle and easy to break, the minimum spacing should be at least 5 times the amount of expansion. For nominal sizes > DN 200, the spacing should not be less than 1.0 m. (Image: Fragezeichen). Example calculation:
The calculated distance … |
|
|
(Image: Measured soil deformation as a result of an expansion [Zimme88]) Supporting findings come from the studies by ZIMMERMANN and the LGA Nuremberg. These are the resulting relationships: Eb = (A – DN) x (4 to 6) Eb = Area of influence A = Expansion (De + 15 %) Example: |
|
|
|
|
|
May 27, 2019 |
|
|
May 27, 2019 The minimum distances to neighbouring utilities and structures depend on:
In case that minimum distances cannot be adhered to, special protective measures, such as open cut excavation at the crossing points, must be taken in order to prevent the transfer of loads. (Image: Underground utilities … |
|
|
May 27, 2019 Soil deformation is generally understood to be the horizontal or vertical positional change of the soil surface or a point inside the soil. Vertical soil deformation in the direction of the ground surface is called heaving and in the opposite direction it is referred to as subsidence, settling or settlement. |
|
|
May 27, 2019 Subsidence is understood to be the vertical displacement of an entire soil stratum as a result of the movement of soil at a great depth. In this case, the size of the displacement can be determined but not its timing [Schmi96]. Settling occurs in granular soils due to a sudden rearrangement of the grain particles caused by the addition of water. For loosely compacted soils, this settling can amount to 5 % of the layer thickness, and for densely compacted … |
|
|
May 27, 2019 (Image: Soil deformation during pipe bursting as per [TTC2001]) |
|
|
May 27, 2019 |
|
|
(Image: Target manhole - capstan winch) (Image: Tension sensor) (Image: Overload protection [Jürge05]) During the pulling-in process, the adherence to the permissible tensile forces on the new pipeline must be ensured by means of continual monitoring (measurement and documentation). Methods of tensile force monitoring:
|
|
|
(Image: Target manhole - capstan winch) Pulling devices automatically limit the tensile force to the predetermined maximum value. Additional systems for the measurement and documentation of the tensile forces on the pulling device (cable winch) are available and include electronic monitoring gauges and detailed printout reports. In some cases, these devices also have a PC interface for convenient data transfer. |
|
|
In order to receive real time data from the pulling head, a data cable must be inserted in advance through the new pipeline and connected to a computer. Otherwise, the data can only be collected after the completion of the pulling-in of the new pipeline. (Image: Tension sensor) |
11094 search results:
