UNITRACC - Underground Infrastructure Training and Competence Center

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 …

May 18, 2020

Partial cutting machines - excavation machines

Excavation machines - classification

May 18, 2020

Partial cutting machines - excavation machines

May 18, 2020

Full-face cutting machines - design of the cutting head

Design of the cutter head

May 18, 2020

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 …

May 18, 2020

Full-face cutting machines - design of the cutting head

Scraper cutting head

(Image: Scraper cutting head with pick bits and scraper teeth (standard bore head) [FI-Rasa])

Scraper cutting heads are nearby, closed, disc-shaped boring heads or cutting wheels with adjustable or fixed supporting plates with soil entry openings that are adapted to suit the size of the maximum particle to be transported.

(Image: Open shield machine with scraper cutting head and mechanical support of the working face - Variably adjustable soil …

May 18, 2020

Full-face cutting machines - design of the cutting head

Rock cutting head

(Image: Rock cutting head with disc cutters and TCI insert roller cutter for hard rock [FI-Rasa])

Rock cutting heads consist of almost closed, disc-shaped basic constructions with usual slot-shaped entry openings (removal slots) and are flat with a rounded periphery, slightly coned or almost convex.

(Image: Rock cutting head of a shield with fluid support of the type AVN 1500 for jacking in rock - view)

May 18, 2020

Full-face cutting machines - design of the cutting head

May 18, 2020

May 18, 2020

Rippers

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Buckets and Cutting Knifes

May 18, 2020

Round Shank Cutter Bits

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Roller cutters

May 18, 2020

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 …

May 18, 2020

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.

May 18, 2020

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)

May 18, 2020

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.

The advantages of the backloading system:

Tools can be changed …

May 18, 2020

Excavation tools

May 18, 2020

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, …

May 18, 2020

Steering of the jacking

Control and steering unit

(Image: Technical components in pipe jacking - control and steering unit)

(Image: Control and steering unit)

Main operator's stand:
Operator's stand, from where the boring process and the forward movement of the shield machine are controlled [ [DINEN12336:2010]].

Operator's stand:
Any place of a shield machine or the trailing shield segment, from where one or several functions of the shield machine, the trailing shield machine or their independent …

May 18, 2020

Steering of the jacking

Steering of the jacking works by means of steering cylinders

Steering cylinder:
Hydraulic cylinders installed inside the boring and steering head, respectively between the front shield segment and the trailing shield segment for introducing or correcting changes of direction of the microtunnelling/shield machine (not found).

By extending/drawing in single steering cylinders, the shield machine is steered out of the direction of the jacking pipes.

(Video: Steering of the shield machine by means of steering cylinders)

May 18, 2020

Steering of the jacking

May 18, 2020

Lubrication of the annular space

Definition lubricant and support medium

Lubricant and support medium:
Liquid with or without solids which is pressed into the annular gap in order to reduce the skin friction between the pipe string and the subsoil as well as in order to support the borehole wall (also called lubricant) [Stein05a].

The aims of using lubricating and support media are:

Reduction of the frictional resistance between pipe string and subsoil
Creating an even contact pressure force by preventing jerky jacking (…

May 18, 2020

Lubrication of the annular space

Definition overcut

Overcut:
The annular gap around the pipe deliberately created by using a cutting head or shield of a greater dimension than the outside dimension of the pipe [ [DINEN12889:2000]].

Overcut:
Half of the difference resulting from borehole diameter and outer pipe diameter (ideally an even annular gap around the pipeline).

(Image: Annular space fluid supported)

May 18, 2020