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Pioneering Underground TechnologiesPioneering Underground Technologies

CORE PRODUCTS

Tunnelling

EPB Shield

Mixshield

Single Shield TBM

Double Shield TBM

Gripper TBM

Partial-face Excavation Machine

AVN Machine

Auger Boring Machines

HDD Rig

Direct Pipe

Vertical Shaft Sinking Machine(VSM)

Mining

Exploration

ADDITIONAL EQUIPMENT

Your contact person

Michael Knabe

Area Manager ProjectManagement | TrafficTunnelling

Phone +49 7824 302-5330Knabe.Michael@herrenknecht.com

250 meters per week of bored and lined tunnelfor the Palomino project, Dominican Republic.

Double Shield TBMContinuous tunnelling at maximum speed

________________ Double Shield TBMs areamong the most technically sophisticated tunnelboring machines. They unify the functionalprinciples of Gripper and Single Shield TBMs inone machine. Under stable geological conditions,the combination of methods allows for theinstallation of concrete segments parallel totunnelling, achieving very high tunnellingperformances. This powerful technology istherefore perfectly suited for excavating longtunnels in hard rock.

Advancing with powerWhen tunnelling with a Double Shield TBM, a rotating cutterhead equipped with disc cutters ispressed against the tunnel face with a pressure of up to 32 tonnes per disc. Due to the rollingmovement of the discs, single pieces – so-called chips – are broken out of the rock. Water jetscan cool the cutting tools and reduce dust formation. Buckets installed at the cutterhead takeup the excavated material. Due to gravity, it slides to the center of the machine throughintegrated muck chutes while the cutterhead rotates and then falls through the funnel-shapedmuck ring onto the machine belt. At the end of the machine belt, the rock chips are passed onto belt conveyors or transport vehicles and removed from the tunnel.

PROJECT CONFIGURATOR

Marcus Lübbers

Product Manager | UtilityTunnelling

Phone +49 7824 302-7707Luebbers.Marcus@herrenknecht.com

GEOLOGY & DIAMETERS FUNCTIONALITYFUNCTIONALITY ADVANTAGESADVANTAGES

High speed due to a continuous tunnelling modeDouble Shield TBMs consist of two main components: a front shield with cutterhead, mainbearing and drive, and a gripper shield with gripping unit, auxiliary thrust cylinders and tailskin.The main thrust cylinders connect the two parts of the shield. They are protected by thetelescopic shield where the shield skins of the front and gripper shield overlap. Thus, DoubleShield TBMs are also called telescopic shields. In stable rock, the machine is braced radiallyagainst the tunnel with the gripper shoes. This means that the front shield can be advancedindependently of the gripper shield using the main thrust cylinders.

The reaction forces during the excavation process are transferred into the rock by theextended gripper shoes. Simultaneously to tunnelling, the segments are installed in the tailskinsection. The auxiliary thrust cylinders serve only to secure the position of the concretesegments placed. When the stroke is completed, the gripper shoes are loosened and thegripper shield is pushed behind the front shield using the auxiliary thrust cylinders. Regrippinglasts only a few minutes, which means that tunnelling is almost continuous. In ideal rockformations, Double Shield TBMs can also operate without segmental lining.

Excavation

Disc cutters break chips from the tunnel face applying high contact pressure

Removal

Buckets, muck chutes and muck ring provide for efficient removal of the excavated material onto a

center belt conveyor

Thrust

Hydraulic main thrust cylinders or auxiliary thrust cylinders push the machine forward

Tunnel lining

Segmental lining

+ High advance rates in stable rock due to continuous tunnelling operation

+ Flexible use in all kinds of rock

+ High level of work safety for the machine personnel in geological fault zones

00 Your Selected Files

Illustration of a typical segmental lining machine (diameter 5.4 m)

Double Shield TBM

A movable telescopic shield provides for access to the tunnelwall during cleaning work in Double Shield TBMs.

Torque box drives allow for local overcut andprecise horizontal and vertical control options.

Safe in geological fault zonesIn fault zones or areas of low rockstrength, radial bracing of the grippershoes is not possible. In thesesections, the telescopic shield can beretracted completely so that the frontand gripper shields form a rigid unit.The necessary thrust forces areapplied using the auxiliary thrustcylinders. As with the Single ShieldTBM, the last segment ring installedserves as a counter bearing toadvance the machine. Thrust and ring building can no longer take place simultaneously. Inturn, this discontinuous mode provides for higher tunnelling safety in difficult sections of thealignment.

Application-related special solutions for difficult casesDouble Shield TBMs have a comparatively long shield skin. In cases of rock convergencethere is therefore an increased risk of the machine becoming jammed. Herrenknechtengineers have developed a range of design solutions to deal with this problem. These includegraded shield diameters and a vertical shift of the longitudinal axes of cutterhead, front andgripper shield, for example. Crumbling rock and excavated material can block the telescopicjoint and the annular gap. This makes it difficult to push the gripper shield ahead. As acountermeasure, Herrenknecht Double Shield TBMs usually have a telescopic shield whichcan be moved independently. Using additional displacement cylinders, access to the tunnelwall can be provided if this is necessary for cleaning or securing measures. Additional drillingdevices and drilling ports in the shield section serve to secure the open telescopic sectionabove the TBM using a pipe arch.

The right drive for any diameterIn the diameter range from 2.8 – 6 meters,Double Shield TBMs are equipped withpermanently installed drives with straight-positioned main thrust cylinders or v-positionedlattice cylinders. Tunnelling control is carried outdirectly by the cylinders. For diameters of morethan 6 meters, movable drives with additionallongitudinal displacement cylinders are generallyused. Through the cylinders, the contact pressureof the drive can be measured directly, makingoptimum use of the power provided. Anarticulation bearing or torque box cylinders helpcontrol the TBM. The latter provide for continuoushorizontal and vertical shift of the drive. In thisway, the cutterhead can be steered precisely in alldirections and can even produce a local overcut.

The cutterhead can be pulled back with all drive types, allowing direct access to the tunnelface.

Meters of tunnel in continuous productionDouble Shield TBMs are mainly used for tunnel projects in changing rock formations. Theyachieve very high tunnelling performances in stable rock by working in continuous tunnellingmode. Therefore, the combined method of Gripper and Single Shield TBM is often thequickest and most cost effective solution for long drives in hard rock.

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