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AT - Pipe Umbrella System


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Introduction

The AT - Pipe Umbrella System is a

pre-support measure used in weak

ground conditions in conventional as

well as mechanized Tunneling. Pipe

umbrella pipes increase the stability in

the working area by transferring loads in

the longitudinal direction and decrease

excavation induced deformations.

The system increases safety in the

working area.

Beside this standard usage, the system

is often applied to increase stability in

portal sections and for the re-excavation

of collapsed sections in underground

construction. Another application area is

ground improvement and waterproofing

in combination with all tunnel construction

methods.

Contents

Introduction ........................... ...................................................................................... 3

Fields of Application ........... .........................................................................................4

Main Advantages ......................................................................................................... 4

System Description ...................................................................................................... 5

System Components .................................................................................................... 5

Specifications ............................................................................................................... 6Technical Features ....................................................................................................... 7

AT - Drilling System ...................................................................................................... 7

AT - Pipe Couplings ..................................................................................................... 8

Installation Procedure ................................................................................................ 10

AT - Pipe Umbrella Automation Unit .......................................................................... 11

Accessories ................................................................................................................ 14

Further References .................................................................................................... 14


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Fields of Application

Main Advantages

Advances in weak ground and ground

conditions prone to subsidence

Advances in alpine fault zones

Installation with conventional

drill jumbos

Execution of pipe umbrella drilling

with on-site personnel

Simple and robust system

components

Fast self-drilling installation

Smallest possible stress relaxation

due to an immediate support of the

borehole wall during installation

Accurate installation due to a

minimized annular gap

Length of pipe umbrella pipes can be

adapted to constricted space

Different pipe coupling types available

to suit different project requirements

Advances in sediments or talus

Portal sections

Advances in frequently changing ground

conditions

Single AT - Pipe Umbrella

Double AT - Pipe UmbrellaSingle AT - Pipe Umbrella with double overlap

Re-excavation of collapsed drifts

or tunnels

Urban Tunneling

Cross section when excavating under an AT - Pipe Umbrella

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System Description

System Components

The AT - Pipe Umbrella System is installed

Using the overburden drilling method

Piecewise

With conventional drill booms

By hydraulic, rotary-percussive drilling

Cooling, flushing, and back-flow of thecutting takes place inside the casing

pipes using water.

AT - Starter Unit with Drill Bit

AT - Extension Tube

Valves in injection holes

Various AT - Adapters

Drill Rods

AT - Grouting Plug (End Plug)


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Specifications 1)

SystemSteel

grade

Modulus of

elasticity

Yield

strength

Outer

diameter

Wall

thicknessWeight

Standard

tube length

Moment of

inertia

Section

modulus

Maximum

moment

(elastic)

Type 2) [N/mm2] [N/mm2] [mm] [mm] [kg/m] [m] [cm4] [cm3] [kNm]

AT - 76

S355 210,000 355

76.1 6.3 10.8 3.0 85 22 7.9

AT - 89 88.9 6.3 12.8 3.0 140 31 11.2

AT - 114 114.3 6.3 16.8 3.0 312 54 19.4

AT - 139 139.7 8.0 26.0 3.0 720 103 36.6

AT - 168 168.0 12.5 48.0 2.0 1,860 221 78.5

1) Deviating structural properties are available on request

2) According to EN 10025-2

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Technical Features

AT - Drilling System

Quick length adjustment of the

AT - Pipe Umbrella System facilitated

by piecewise installation

Simple connection of extension tubes

even in restricted space

High drilling accuracy of pipe

umbrella drills

The drilling energy is transferred via

drill rods and an inside adapter onto

the single-use drill bit of the AT - Starter

Unit. The cooling and flushing medium is

immediately transported from the drill bit

front backward inside the umbrella pipes.

After completion of the installation, the

single-use drill bit remains at the toe of

the borehole; adapter and drill rods areremoved and re-used for consecutive

pipe installations.

Loss or blocking of a drill bit is

impossible because it is fixed

within the starter unit

A single-use drill bit ensures the same

high quality for each drilling process

Application of a single-use drill bit

provides optimum pre-conditions to

achieve the total drilling depth every

time

The drill bit type can be adapted togiven geological conditions

Stable drilling direction due to stable

drill bit orientation

Disconnecting and reconnecting of

drill rods is possible at any time

Small overcutting ensures the lowest

possible stress relaxation

Special pipe coupling types for

different static requirements

The use of the AT - Pipe Umbrella

Automation Unit increases the drilling

progress, minimizes over-excavation

(saw tooth profile), and increases

personnel safety

Application of preventers possible

Recording and control of the grouting

process using a flow-pressure meter


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AT - Pipe Couplings

Standard Thread Connection

Squeezed Connection

The AT - Pipe Umbrella System is installed

with conventional drilling machines.

Single pipes are installed piecewise at a

length that fits the drill boom length.

When using a standard thread connection, an outside and inside

thread is cut into the ends of the pipe umbrella pipes. This type of

coupling reduces the cross-section of the pipe at the area of the

thread connection. Thereby, the section modulus is decreased

as well. Besides the geometrical conditions of the thread, the

overall quality of the pipes is a major concern for the maximum

load-bearing capacity. In general, calibrated tubes reach a higher

resistance against bending than non-calibrated ones.

Simplest connection type

Installed tubes show a constant inner diameter

The stiffness of the connection is considerably lower than

the stiffness of the standard pipes The rupture load of the connections is comparable to the

design load of standard pipes; it is clearly lower for

non-calibrated tubes

Further decrease of the load-bearing capacity if mistakes

occur during screwing or grouting of the pipes

A lower load-bearing capacity can only be compensated by

a higher number of pipes

Dislocation of the coupling positions in the longitudinal

direction does not increase the load-bearing capacity

Installation can be accomplished with or without an

AT - Pipe Umbrella Automation Unit

This connection type can be recommended for the installation

of measurement instrumentations and for ground-improving

injection works.

A squeezed connection consists of a reduced pipe end which is

force-fitted with its counter piece. In the coupling area, the cross

section stays constant and the section modulus is decreased.

The ultimate load of this connection is higher than the elastic

design load of a normal pipe (> 1.5)

Transition from elastic to plastic material behavior begins at

approximately of the elastic design load (standard pipe)

Reduction of the inner diameter in the connection area

Reduction of the stiffness against bending in the connectionarea

Installation can only be accomplished with an AT - Pipe

Umbrella Automation Unit incorporating a squeezing unit

Usage of this connection type can be recommended for all

advances where a pipe umbrella is installed because of its

static load-bearing capacity.

Type and quality of the pipe coupling

are decisive factors for the maximum

achievable load-bearing capacity of the

support system.

For this reason, three different types of

couplings are available for the AT - Pipe

Umbrella System.

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AT - Pipe Couplings

Nipple Coupling

Nipple couplings are an additional steel nipple where a thread

connection is pressed and welded into both ends of the extension

tubes. This ensures that the section modulus at the coupling is

never lower than the section modulus of the standard pipe.

The elastic design load is equal to the one of a

standard pipe

Stiffness in the elastic range is comparable to the one

of a standard pipe

Reduction of the inner cross-section

Installation can be accomplished with or without an


Usage of this connection type can be recommended for advances

where the static load-bearing capacity is required to achieve stabl

conditions and settlement limitations are part of the design.

00 1 2 3 4 5 6 7 8 9

20

40

60

80

100

120

140

160

180

Load[kN]

Deflection [mm]Standard Pipe

Standard Thread Connection

Squeezed Connection

Nipple Coupling

Elastic Material Behavior (analytic)

Plastic Material Behavior (analytic, bi-linear material characteristics)

200

Elastic Design

Load


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Installation Procedure

1. For drilling, the AT - Starter Unit with drill bit is assembled

together with the first AT - Extension Tube, the AT - Adapter,

and the drill rod onto the drill boom

2. Installation of the first AT - Extension Tube

3. The next drill rod with AT - Extension Tube is connected

to the previously installed pipe and the drilling process is

continued afterwards

4. The last step shall be repeated until the designed length of the

AT - Pipe Umbrella has been installed

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Main Advantages


The AT - Pipe Umbrella Automation Unit

allows automated feeding, screwing, and

installation of extension tubes plus

drill rods.

Shorter manipulation times due to

exact and automated feeding

Faster construction of a pipe umbrella

support system

Higher occupational safety

No handling besides moving parts of

the drilling machine

Simple re-charging of extension tubes

via a loading basket

Remote-controlled feeding of tubes

Less manpower required

Optimum utilization of the working

space

Smaller saw-tooth shaped profile and

thereby less excavation volume

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Assembly groups

Specifications

Screwing unit and centering/clamping device

Loading device and pipe feeding system

Electric switch case

Central guiding device

Remote control

Hydraulic control box Pipe deposition

Characteristics / Assembly groupDimensions

(L x B x H) [mm]Weight [kg]

Pipe deposition 1,040 x 230 x 350 28

Screwing unit and centering / clamping device 1,165 x 360 x 745 160

Loading device and pipe feeding system 3,485 x 350 x 565 160

Central guiding device 155 x 190 x 220 12

Hydraulic control box 550 x 275 x 345 60

Electric switch case 380 x 600 x 350 35

Remote control 250 x 140 x 180 2.3

Characteristics Unit Value Remark

Total weight (gross) [kg] 460 - 490Deviations possible,

depending on the type

Electric supply [V] 24 DC

Hydraulic supply [L/min] 20 At approx. 170 [bar]

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Assembly groups

Screwing unit and centering/clamping device Hydraulic rock drill

Central guiding

device

AT - Starter Unit wi th dril l bit

Foundation ground

Pipe deposition with AT - Extension Tub

and drill rod

Drill boom

Hydraulic control box

Loading device and pipe feeding system with AT - Extension Tube an

drill rod

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Accessories

Further References

Flow-Pressure meter

Injection packer

Volkmann, G.M. & W. Schubert 2007.

Geotechnical Model for Pipe Roof

Supports in Tunneling. In Proc. of

the 33rdITA-AITES World Tunneling

Congress, Underground Space -

the 4thDimension of Metropolises,

Volume 1. eds. J. Bartak, I.Hrdina,G.Romancov, J. Zlamal, Prague,

Czech Republic, 5-10 May 2007,

Taylor & Francis Group, ISDN:

978-0- 415-40802. app. 755-760

Volkmann G.M. & Schubert W. 2008.

Tender Document Specifications for

Pipe Umbrella Installation Methods.

In proceedings of the 34thITA-AITES

World Tunneling Congress, Agra, India,

22-24 September 2008, pp. 285-293

AT - Pipe Umbrella Geometry

Calculator

Installation Manual for the

AT - Pipe Umbrella System

Mortar-Mixing pump

DYWIInject Systems

Fishing tab

Drill rod wrench

Chain pipe wrench

Rock drilling equipment: shank adapter,

coupling, and coupling adapter

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0 4 1 9 7 1 / 0 4 1 3 w e b h e

EMEADYWIDAG-Systems International GmbHAlfred-Wagner-Strasse 14061 Pasching/Linz, AustriaPhone +43-7229-610 49 0Fax +43-7229-610 49 80E-mail [email protected]

North AmericaDSI Underground Systems Inc.9786 S Prosperity Road

West Jordan, UT 84081, USAPhone +1-801-973 7169Fax +1-801-973 7172E-mail [email protected]

South AmericaDSI Chile Industrial Ltda.Las Encinas #1387, Valle GrandeLampa, Santiago de Chile, ChilePhone +56-2-596 96 20Fax +56-2-596 96 69E-mail [email protected]

APAC/ASEANDYWIDAG-Systems International Pty. Ltd.25 Pacific HighwayBennetts Green, NSW 2290, AustraliaPhone +61-2-49 48 90 99Fax +61-2-49 48 99 56E-mail [email protected]/au

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Please note:This brochure serves basic informationpurposes only. Technical data and informationprovided herein shall be considerednon-binding and may be subject to changewithout notice. We do not assume any liabilityfor losses or damages attributed to the useof this technical data and any improperuse of our products. Should you requirefurther information on particular products,please do not hesitate to contact us.

ALWAG(AM 952/79), AT(AM 6138/2003),AT-SYSTEM (AM 6139/2003),DYWI(4197869), LSC(AM 4326/2008),OMEGA-BOLT(3258282),POWER SET(AM 6163/2002), andTUBESPILE(AM 4328/2008) are registeredtrademarks of DYWIDAG-Systems International GmbH.Combi Coatand CT-Boltare trademarksof Vik rsta AS.DYWIDAG-Systems International GmbHis a partner of Vik rsta AS.

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