UNITRACC - Underground Infrastructure Training and Competence Center

Utility Tunnelling - Geotechnical investigations

Soil and rock classification related to trenchless installation

Soil and rock classification according to abrasiveness

The abrasiveness of a rock material is dependent on numerous parameters, among which are:

The content of abrasive minerals with a MOHS hardness > 5.5 (steel),
Fabric and texture,
Framework of discontinuities,
Effects of the change of the rock mass due to weathering.

[Thuro98b]

Sep 24, 2008

Utility Tunnelling - Geotechnical investigations

Soil and rock classification related to trenchless installation

Calssification of the abrasiveness with reference to the CAI Index

(Table: Classification of rock material with reference to the CAI index [Thuro98b])

(Table: CAI Index (Empirical values) for various types of rock material to Büchi [Büchi95])

Sep 22, 2008

Utility Tunnelling - Geotechnical investigations

Soil and rock classification related to trenchless installation

May 19, 2011

Utility Tunnelling - Geotechnical investigations

This presentation is part of the series of presentations "Utility Tunnelling" and deals with the fundamentals in geology, hydrogeology and geotechnical engineering.

Jan 01, 1900

Content

Today, supply and discharge lines are still predominantly installed by using the open-cut method: a trench is dug, the lines are installed. Under the protection of an embankment or sheeting and the trench is filled afterwards.

In the face of the numerous disadvantages as well as the citizens' growing environmental consciousness in the future it is urgently necessary to take trenchless technology into account much stronger than until today as an alternative …

Oct 02, 2008

Terms and definitions

Definition jacking pipes

Jacking pipe:
Prefabricated pipe with non-restrained, tensile-restrained or restrained joint, flexible or rigid pipe joint within the wall thickness and smooth, even outline (exception: ductile cast iron pipes with cast socket for fluid flushing directional drilling) which is pressed, pushed, rammed or pulled into the subsoil, respectively cavity [Stein05a].

(Image: Reinforced concrete jacking pipe) (Image: Jacking pipes of different diameters and …

Oct 02, 2008

Terms and definitions

Jan 25, 2005

Functions of jacking pipes

Jacking pipes have a double function: They constantly support the excavated cavity and, in the case of a single shell lining, they provide the structure of the pipeline (final lining).

(Image: View into the jacking pipes) (Image: Reinforced concrete jacking pipes) (Image: Example of the final lining of a pipeline tunnel)

Oct 02, 2008

Functional classification of the jacking pipes

In trenchless installation, casing pipes, host pipes, utility ducts and utility tunnels act as cavity security and for carrying or supporting the actual product pipe(s).

(Image: Functional classification of jacking pipes)

Oct 02, 2008

Definition product pipeline, casing pipe and host pipe

(Image: Product pipes [FI-Steina])

Product pipeline:
Pipeline for the transport and distribution of liquids and gases - also including solids [Stein05a].

(Image: Casing pipes [FI-Steina])

Casing pipe:
Pipeline remaining inside the subsoil for accommodation and for protection of a product line or a cable against external stress [Stein05a].

(Image: Bundled installation inside the host pipe [FI-Steina])

Host pipe:
Pipeline remaining in the subsoil …

Oct 02, 2008

Definition utility duct and utility tunnel?

(Image: Utility duct)

Utility duct:
Non-accessible, underground installations for orderly installation of supply and/or disposal lines utilizing a structural shell for line fastening. The spacing between the lines are not filled in order to maintain the possibility of later access [Stein05a].

(Image: Man-accessible utility tunnel [FI-Steina])

Utility tunnel:
A man-accessible utility tunnel is an enclosed corridor-like structure for the accessible …

Aug 04, 2008

Jacking pipes - materials

(Image: Materials for jacking pipes)

Oct 02, 2008

Pipe materials with reference to the type of pipeline

(Table: Suitable pipe materials with reference to the type of pipeline)

Oct 02, 2008

Installation methods with reference to the pipe material

(Table: Suitable methods for installing jacking pipes with reference to the material)

Oct 02, 2008

Demands on jacking pipes according to EN 12889

(Image: Attention!)

According to EN 12889, "the installation shall not commence before the following criteria have been agreed between the specifier and installer. These may be obtained from appropriate product standards or from the pipe manufacturer:

Internal pipe diameter
External pipe diameter
Pipe length
Tolerances on dimensions
Safe jacking load or pulling force
Type and performance of joints
Longitudinal flexibility (acceptable bending …

Jun 06, 2006

Necessary functions and dimensions of pipes and fittings

(Image: Attention!)

Dimensions of pipes and fittings: The product standards must provide information on nominal sizes, diameters and tolerances, straightness, rectangularity of end faces, pipe length and continuity of invert.

Roughness of pipe wall: Inside walls of pipes must be free of visible defects that may negatively affect their hydraulic performance.

Condition: Pipes and joints shall be free of defects that may have a negative impact on their …

Jun 06, 2006

Necessary functions and dimensions of pipes and fittings

(Image: Attention!)

Jetting resistance: Pipes must be resistant to stress resulting from jetting.

Modification: Manufacturers must provide information on in-situ handling.

Coatings and linings: If coatings, linings or other protective measures are required, it is necessary to specify appropriate indications in product standards, also in consideration of the installation. It may be necessary to specify additional protections for joints.

Long-term behaviour:

Jun 06, 2006

Necessary functions and dimensions of pipes and fittings

(Image: Attention!)

Load bearing capacity and stiffness: The following values are particularly necessary for the calculation of the characteristic mechanical behaviour of pipes in dependence of the type of their installation, their use and material: modulus of elasticity, density, tensile strength, yield limit, compressive strength, bending strength, longitudinal compressive strength and vibration amplitude.

Temperature: Pipes and joints shall …

Oct 02, 2008

Perpendicularity of the end faces

(Image: Attention!)

The perpendicularity of end faces (perpendicularity of the pipe axis) of jacking pipes for gas, water as well as drains and sewers is of particular importance for transferring the jacking forces when pushing-in, pressing-in or ramming-in and for the dimensioning of the pressure transfer ring [DWAA125:2014].

(Image: Measurement of the rectangularity of end faces)

The perpendicularity of the end surface is defined according …

Oct 02, 2008

Permissible deviations of the rectangularity

(Table: Permissible deviations of the rectangularity of the end faces with reference to the pipe material and the nominal size in mm)

Oct 02, 2008

Construction length and continuity of invert

(Image: Attention!) In determining the pipe length of the jacking pipe to be inserted (pipe length plus when available, thickness of the pressure transfer ring in the uncompressed condition), the installation method must be taken into account.
(Table: Permissible pipe length tolerances with reference to the nominal size of the jacking pipes)	Preferred lengths of jacking pipes for pressing- in, pushing-in or ramming-in are 1000 mm, 2000 mm, 3000 …

Oct 02, 2008

Demands on the pipe joints of jacking pipes


Tightness against internal and external pressure (Image: Leaktightness)	Transfer of the longitudinal force by securing the lateral stability (Image: Transfer of the longitudinal force)	Possibly corrosion protection of the end faces of the pipe (Image: Corrosion protection end faces of the pipe)

Oct 02, 2008

Tightness against internal and external pressure

(Image: Leaktightness)

All parts of the pipeline including the pipe joints and sealings must be designed, produced and examined according to the objective to guarantee the tightness during the construction works (construction state) and the whole planned service life (operation state) taking the longterm properties of the sealing medium as well as potential movements of the pipe joints under the respective loads into consideration.

(Image: Dimensions …

Oct 02, 2008

Transfer of longitudinal forces

(Image: Transfer of the longitudinal force)

In the case of trenchless installation, differences are made with regards to the transfer of the jacking forces between the following restrained pipe joints:

Non-restrained pipe joints for transferring compressive stresses when pressing-in or pushing-in [DWAA161:2017]
Tensile restrained pipe joints for transferring tensile forces when pulling-in
Restrained pipe joints for transferring compressive …

Oct 02, 2008