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Mar 19, 2024

Modules

Utility Tunnelling - Pipe jacking - Part 2

Errors and consequences of damage

Mar 19, 2024

Modules

Utility Tunnelling - Pipe jacking - Part 2

Errors and consequences of damage

Mar 19, 2024

Modules

Utility Tunnelling - Pipe jacking - Part 2

Errors and consequences of damage

Mar 19, 2024

Modules

Utility Tunnelling - Pipe jacking - Part 2

Errors and consequences of damage

Mar 19, 2024

Modules

Utility Tunnelling - Pipe jacking - Part 2

Errors and consequences of damage

Mar 05, 2024

Modules

Utility Tunnelling - Pipe jacking - Part 2

Errors and consequences of damage

Feb 10, 2020

Modules

Utility Tunnelling - Geotechnical investigations

Introduction

To the field of Geotechnology belong, amongst others, the following scientific disciplines:

  • Geological engineering: Science that incorporates the application and evalutation of geological know-how and consolidated findings when dealing with construction works.
  • Soil and rock mechanics (geomechanics): Science with the objectives…
    • To investigate the subsoil,
    • To describe and classify the soil,
    • To determine the strength and deformation behaviour of …

Sep 22, 2008

Modules

Utility Tunnelling - Geotechnical investigations

Jan 01, 1900

Modules

Utility Tunnelling - Pipe jacking - Part 2


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 …

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with partial excavation by hand

(Image: Simple hand shield - working face with natural support)

Hand shields are non-mechanised open shield machines in which the soil at the working face is loosened by hand using auxiliary tools (pickaxe, spades, shovels or pneumatic hammer). The removal of the spoil is carried out with the aid of conveyor belts, transport carts or tracked conveying buckets (dump trucks).

Examples:

(Image: Hand shield (external diameter 4672) with working …

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with partial excavation by hand

(Table: Classification of hand shields according to the type of working face support [FI-Steina])

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with partial excavation by hand

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with partial excavation by hand

(Image: Attention!)With partial support, the surface of the working face is divided into sections and is either supported by means of natural partial support on bench plates (bench (plate) or platform shields) and/or by means of mechanical partial support using breast plates.

(Image: Hand shield with breast plates - working face with mechanical partial support) (Image: Hand shield with benches (Bench shield) - working face with natural partial support) (…

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with partial excavation by hand

(Image: Attention!)

Shield machines with partial excavation by hand are predominantly used for:

  • short jacking distances under 50 m
  • crossings of traffic ways
  • jacking of an extraordinary cross-section
  • groundwater-free soil or rock

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with partial excavation by hand

SM-T1 - areas of application:

  • stable, cohesive soil, i.e. firm-stiff and very stiff cohesive soil (soil class LBM 2 and 3 and/or LBO 2 and 3 according to DIN 18319) with a compressive strength of approx. 1.0 N/mm2
  • Rock with uniaxial compressive strength ≥ 5 N/mm2 (classes FD 2 to 4 and/or FZ 2 to 4)

SM-T2 - areas of application:

  • loose to densely compacted non-cohesive soil (classes LNE 1 to 3 and/or LNW 1 to 3) with a particle size concentration < …

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

(Image: Shield with fixed intalled excavation machine - working face with natural support (SM-T1))

The shield machines with mechanical partial excavation correspond in concept to the design of the hand shield. They feature a mechanised open (SM-T1 or SM-T2) or closed (SM-T3 or SM-T4) shield with a fixed installed excavator for partial excavation of the soil or rock at the working face.

Examples:

(Image: Principles of support for open shield …

Aug 25, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

(Table: Classification of shield machines with mechanically partial excavation according to their type of work face support [FI-Steina])

Aug 26, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

Shield machines with compressed air support (SM-T3) are closed shields based on shield types SM-T1 and SM-T2 in which the working face is pressurised with the flow of compressed air, e.g. "air with a positive pressure of more than 0.1 bar above atmospheric" in order that the working chamber (defined in EN 12110 [DINEN12110:2014] as "space in which work is carried out in compressed air") can be kept free of infiltrating water and the stability of …

Aug 26, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

Working chamber:
Space in which work in compressed air is carried out.
[DINEN12110:2014]

Air lock:
Pressure vessel with one or more chambers with access doors, which can be sealed and pressurised with compressed air.
[DINEN12110:2014]

Material lock:
Air lock through which only material or equipment goes into or out of the working chamber.
[DINEN12110:2014]

Personnel lock:
Air lock through which only persons go into or out of the working chamber.

Aug 26, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

(Image: Attention!)

When pipe jacking under air pressure, the working chamber e.g. the region from the working face to the air lock ("pressure vessel with one or more chambers with access doors which can be sealed and pressurized with which compressed air or gas" [DINEN12110:2014]) must be made airtight by means of a pressure bulkhead ("equipment which separates spaces with different pressure levels" [DINEN12110:2014]) from the ambient atmosphere.

Aug 26, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

The arrangement of the locks is of central importance from a site operation point of view. In principle, three variants with different effects on the size of the working chamber are possible in pipe jacking:

  • Air lock(s) above or in the starting shaft ("shaft locks")

  • Moving air lock(s) in the pipe string

  • Moving air lock(s) in the trailing shield segment

Air lock above the starting shaft ("shaft lock")

(Image: Principle possibilities of arranging …

Aug 26, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

Shield machines with compressed air support are used [Krets72]:

  • In soil types where the lowering of the groundwater is not to be recommended on technical, ecological or economic reasons
  • In regions where the lowering of the groundwater could cause damaging subsidence
  • For jacking under water ways
  • For stabilizing the working face

Aug 26, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

The limits of use for jacking in compressed air are determined by [Krets72]:

  • The pressure permitted by the compressed air ordinance [ELEXV97] of a maximum of 3.6 bar
  • The air permeability of the subsoil
  • The minimum cover depth above the crown of the pipe (assessment of blow-out safety)
  • Economics, which can only be achieved with longer jacking lengths due to the high investment costs
  • The time and costs due to persons and materials having to …

Aug 26, 2008

Modules

Utility Tunnelling - Pipe jacking - Part 2

Shield machines with mechanical partial excavation

Blowout:
A blowout is the abrupt escape of compressed air out of the working chamber through loosened or remoulded subsoil when working under compressed air. In this case, it refers to the sudden escape (also blowing out) of the supporting compressed air on the surface of the site or the water bed [DS853].

In general, there are two types of blowouts [Baben99]:

  • Gasometer blowout
  • Erosion blowout

(Image: Types of blowouts - Gasometer blowout) (Image: …

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