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For the replacement by in-situ concrete, the by-pass pipeline is located outside the completed gallery and the pipeline to be replaced is removed.

The new pipeline is now installed in the in-situ concrete, the connection pipelines are reconnected and the by-pass pipeline is removed.

(Image: Possibilities of interior work using gallery techniques (heading) with reference to [Düsse] [Image: S&P GmbH])
(Image: Inspection) (Image: Leaktightness)

The finishing work consists of the following tasks:

  • CCTV-inspection of the new pipeline

  • leaktightness testing of the new pipeline

Nov 04, 2016

Modules

This module focuses on the fundamentals of the trenchless replacement of gas, water, wastewater pipelines using the gallery techniques known from the mining industry. In addition, the individual steps of the gallery heading process with steel and timber support are described - from the preparatory measures to the final work. In addition, the areas of application and limitations of gallery heading, the measures for quality assurance as well as the advantages and disadvantages of this method are presented.

After completing this module, you will have a sound knowledge of:

  • characteristics of gallery heading;
  • working steps of this form of heading;
  • relevant aspects for quality assurance.

This lecture deals with the application fields and limits of gallery techniques (heading), the measures of quality assurance as well as the advantages and disadvantages of this process.


Gallery techniques (heading) are applied in the following fields and under the following conditions:

  • the replacement of pipelines in the non-accessible area

  • the replacement of pipelines at great depth

  • high traffic density in the range of the pipeline that has to be replaced

(Image: Attention!)

Preconditions for the application of gallery heading:

  • non-existence of groundwater (possibly by groundwater lowering or discharge if this is technically …

(Table: Material restrictions for gallery techniques (heading))

(Table: Material restrictions for gallery techniques (heading))

(Image: Documentation)

In order to achieve a high quality replacement by means of gallery techniques (heading), it is necessary to establish a complete documentation of all relevant process steps.

The quality assurance should comprise of at least the following measures:

  • internal quality control

  • geotechnical measurements

  • a quality assurance manual (QA-manual)

(Image: Documentation)

Within the scope of internal quality control, the properties or parameters of the applied materials indicated in the verification certificates of suitability must be proven by means of component samples and reference samples.

The results of the internal quality control must be recorded.

The recording of the internal quality control comprises the following parts:

  • incoming goods inspection of the new pipeline

  • recording of the …

(Image: Documentation)

Parallel to the ongoing construction measurement of the gallery, geotechnical measurements should be carried out before and during the construction process in order to confirm the positional stability of the gallery during the heading process. This is needed to detect potential ground deformations and to determine the effects on adjacent buildings.

Surface levelings are suited for measurement methods to detect advancing or trailing …

(Image: Documentation)

For the verification of the quality assurance of the applied materials and accomplished works, a QA-manual should be established by the contractor.

The QA-manual should contain the following indications and verifications:

  • verification of the required qualification, management competence and reliability of the contractor as well as an internal and external quality control*)

  • internal and external control of the material production …

Advantages of gallery techniques (heading):

  • Starting excavation can be outside the line;

  • Accessibility of connection sewers;

  • No target excavation required,

  • Adaptable to changing subsoil conditions;

  • Fewer traffic restrictions;

  • Flow (Drainage) capability is easy to secure;

  • Pipeline to be replaced and contaminated soil in the cross section are removed.

Disadvantages of gallery techniques (heading):

  • The process requires much time and labour;

  • If …

Congratulations!

You have successfully finished this lesson.

Next you will have the opportunity to review the newly acquired knowledge with an interactive questionnaire.

You can of course still navigate back to any point in the lessons if you wish to review a specific point or subject.

Stay curious!

Nov 04, 2016

Modules

This module focuses on the fundamentals of the trenchless replacement of gas, water, wastewater pipelines using the gallery techniques known from the mining industry. In addition, the individual steps of the gallery heading process with steel and timber support are described - from the preparatory measures to the final work. In addition, the areas of application and limitations of gallery heading, the measures for quality assurance as well as the advantages and disadvantages of this method are presented.

After completing this module, you will have a sound knowledge of:

  • characteristics of gallery heading;
  • working steps of this form of heading;
  • relevant aspects for quality assurance.

This lesson focuses on the trenchless replacement of pipelines using the pipe extraction method.

The aim is to provide a quick introduction to the subject with regard to process variations and operating limits and limits, as well as to convey the advantages and disadvantages of this replacement process.

What is pipe replacement?

Pipe replacement is the construction of a new drain or sewer, on or off the line of an existing drain or sewer, the function of the new drain or sewer incorporating that of the old one.

The replacement is always carried out at least in section lengths of the sewer using:

  • The open cut method

  • The semi open cut method

  • The trenchless method

(Image: Replacement of sewers using the open cut method)
(Image: Replacement …

(Image: Overview of replacement methods in trenchless construction)

The pipe extraction - also called the pushing/pulling process - is a method for the trenchless replacement of existing pipelines.

A characteristic of this process is the sectional pulling in of new product pipe and the simultaneous pushing out of the old pipe, with the aid of hydraulic pulling-equipment placed in the reception pit.

During this process, the pipe to be replaced is completely removed out of the subsoil.

(Image: Pushing-pulling process …


Pipe Extraction

The original pipe is extracted by pulling or pushing and is simultaneously replaced by a new one. When the diameter of the new pipe is significantly larger than the old one, an expander is used [DINEN12889:2000].