UNITRACC - Underground Infrastructure Training and Competence Center

Definition open shields

Open shields:
Shield machine without pressure tight sealing between the working face and the following pipe string [Stein05a].

Open shields do not have a pressure-tight seal between the working face and the subsequent pipe string. They are characterized by relatively good access to the working face and easy-to-use machine technique.

(Image: Hand shields - Overall view of a hand shield (external diameter 2098 mm) [FI-Nishi]) (Image: Open shield) (Image: …

Aug 08, 2008

Shield machines

Shield machines with partial excavation

Shield machines with partial excavation feature an open (SM-T1 or SM-T2) or closed shield (SM-T3 or SMT4) and partial loosening of the soil or material at the working face.

Shield machines with partial excavation of the working face are grouped according to the method of excavation into:

Shield machines with partial excavation by hand (hand shields)
Shield machines with mechanical partial excavation
Shield machines with hydraulic partial excavation

Aug 08, 2008

Shield machines

Definition closed shields

Closed shields:
Shield machines equipped with a pressure bulkhead between the working face and the shield tail in order to build up an artificial pressure at the working face [Stein05a].

(Image: Possible designs of boring heads for earth pressure balance shields - Shield with eight-spoke cutting wheel and circumferential rim (external diameter 3100 mm) [Breme])

Closed shields are – depending on the used pressure balancing fluid – executed with …

Aug 08, 2008

Shield machines

Shield machines with full-face excavation

Shield machines with full-face excavation (SM-V) differ from those with partial excavation (SM-T) in that they process and loosen the whole working face in one working step by means of a rotating boring head equipped with corresponding excavation tools.

(Image: Shield machines with full-face excavation - Working face with natural support SM-V1)	(Image: Shield machines with full-face excavation - Working face with mechanical support SM-V2)
(Image: …

Aug 07, 2008

Shield machines

Aug 08, 2008

Partial cutting machines - excavation machines

Excavation machines

(Image: Attention!) Excavation machines are used with shield machines with partial excavation. Operating and steering of the shield machine are carried out directly at the site by a machine operator who has a continuous view of the working face.
(Image: Shield machine with fixed installed boom cutting machine - With axial cutting head)	(Image: Axial cutter head of the boom cutting machine equipped with round shank cutter bits)	(Image: Principles …

Aug 08, 2008

Partial cutting machines - excavation machines

Excavation machines - classification

Aug 07, 2008

Partial cutting machines - excavation machines

Aug 08, 2008

Full-face cutting machines - design of the cutting head

Design of the cutter head

Aug 08, 2008

Full-face cutting machines - design of the cutting head

Cutting wheel

(Image: Three-spoke rim cutting wheel with scraper teeth (standard bore head) [FI-Rasa])

The cutting wheel is a largely openly designed drilling head that is not used for the mechanical support of the working face. Their advantages lie with the low coverage and thus the good accessibility of the working face when needed. A distinction is made between the spoke and the rim cutting wheel [Maidl98].

(Image: Possible designs of boring heads for earth …

Aug 08, 2008

Full-face cutting machines - design of the cutting head

Scraper cutter head

Aug 08, 2008

Full-face cutting machines - design of the cutting head

Rock cutter head

Aug 07, 2008

Full-face cutting machines - design of the cutting head

Aug 08, 2008

Excavation Tools

Aug 08, 2008

Rippers

Aug 08, 2008

Buckets and Cutting Knifes

Aug 08, 2008

Round shank cutter bits

Aug 08, 2008

Roller cutters

Aug 08, 2008

Force distribution at the disc cutter

(Image: Attention!)

With increasing stability and/or hardness of the rock and rolling speed of the disc cutters the temperature and wear of the single discs increases [Schad03].

(Image: Forces affecting the disc cutters ? single disc cutter with reference to [Schad03] [Image: S&P GmbH])

Forces affecting the disc cutters - single disc …

Aug 08, 2008

Centre cutters

Centre cutters are excavation tools arranged in advance in the centre of the boring head in order to release the pressure in the centre of the working face during boring and especially in cohesive soils such as clay and silt with low to high plastic properties to counteract sticking of the boring head.

Aug 08, 2008

Possible combinations of different excavation tools

(Table: Combination possibilities of the various excavation tools as well as the utilization of stone crushers with reference to the subsoil conditions)

Aug 08, 2008

Backloading - exchange of excavation tools

(Image: Pros and cons)

Backloading:
In shield machines with full face excavation, special attention must be paid to the possibility of changing the excavation tools without changing the support conditions of the working face. One method to securely and easily perform the task underground without withdrawing the machine from the back of the drill head is the so-called backloading system.

Advantages of the backloading system:

Tools can be changed without …

Aug 07, 2008

Excavation tools

Aug 08, 2008

Steering of the jacking

Jacking monitoring

(Image: Attention!)

For a scheduled execution of a pipe jacking project, at any time there must be exact knowledge about the position and direction data (inclination and pitch angle, yaw angle, rolling angle) of the jacking machine, so a comparison of present and nominal position becomes possible and the steering can be corrected.

When determining the position and direction the following equipment is used:

optical measuring devices (theodolite, …

Aug 04, 2008