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Special Aspects for Building a Motorway on a 185 m Deep Dump
Aspects particuliers pour construire une autoroute sur un remblai de comblement de 185 m
Vogt N., Heyer D., Birle E., Vogt S.
Zentrum Geotechnik, Technische Universität München, Munich
Dahmen D., Karcher C., Vinzelberg G., Eidam F.
RWE Power AG, Cologne
ABSTRACT: The major part of the new motorway A 44 will be constructed on a deep dump of the Garzweiler open cast mine,
reaching a maximum depth of 185 m. The soils are placed by large scale spreaders in a bulk flow. Thus, the uncompacted dump
possesses a pronounced compressibility and can exhibit long-term time-dependent deformations, mainly as a result of particle
redistribution in the dump. The magnitude and rate of the deformations depend on numerous parameters, of which the soil type is the
most important. With this background, the RWE Power AG has developed a concept for dumping the pit with selected soil-types on
which the autobahn will be constructed. This concept only allows the dumping of mainly coarse- and mixed-grained soils beneath the
future motorway. Extensive laboratory and field tests have confirmed that the settlements along the A 44 route, compared to similar
dumps in the area of the Rhenish lignite mines, can be clearly reduced. Based on the laboratory and field tests a model that allows the
calculation of the time- and stress-dependent deformations within the dump, as well as on the surface along the planned autobahn, has
been developed.
RÉSUMÉ: La nouvelle autoroute A 44 sera construite sur la zone remblayé de la mine à ciel ouvert Garzweiler, zone qui atteint une
profondeur maximale de 185 m. La terre du remblai est déversée par des gros tombereaux rigides en grande masse. Les sols
présentent dès lors une densité relativement faible ce qui se traduit par une compressibilité prononcée lors du processus de
remplissage et peut conduire à des déformations à long terme, principalement en raison de la redistribution des particules dans le
corps de remplissage. L'ampleur et le rythme des déformations dépendent de nombreux paramètres. Le type de sol est le plus
important. Dans ce contexte, la société RWE Power AG a développé un concept de remplissage de la fosse sur laquelle l'autoroute
sera construite qui utilise une sélection des granules et sables lors du déversement. Des essais à grande échelle, en laboratoire et en
place, ont confirmé que les déformations à la surface du remblai peuvent être nettement réduites par le choix ciblé des matériaux. Un
modèle de mécanique des sols permettant de représenter les déformations à la surface du sol a été développé à partir des expériences
en laboratoire et sur le terrain.
KEYWORDS: dump, mining, settlements, time-dependent deformation, creep, sand
MOTS-CLES: mine, comblement, tassement, déformation, fluage, sable
1
INTRODUCTION
The Rhenish lignite mining area covers the flat plains of the
Cologne Lowland between the cities of Aachen,
Monchengladbach and Cologne. With a total annual output of
some 100 million tons of lignite the 3 currently active large-
scale open cast mines contribute to 12 % of the electricity
production in Germany. The area under consideration is part of
the Garzweiler open cast mine, presently covering an area of
48 km
2
. In order to exploit the annual 35-40 million tons of
lignite, a fivefold magnitude of overburden (150 million cubic
meters) must be excavated and dumped. The current mining
permit stipulates the year 2045 by which the exploitation will
have to end east of the city of Erkelenz.
Because of the westwards progressing exploitation, the
motorway A 44 has been closed since November 2005 over a
stretch of about 10 km. Since then traffic has been redirected
along the almost parallel running autobahn A 61. The area of
the former autobahn is currently used for mining purposes.
According to the planning schedule, the open cast mine will
reach the autobahn A 61 right-of-way by the year 2017. Before
the A 61 can be closed and dismantled, the A 44 that has been
closed must be reopened to traffic. The major part of the new
autobahn comprising 6 lanes within a cross section of 42.6 m in
width will be constructed on dumped soils of the Garzweiler
open cast mine, which have a maximum depth of 185 m (Köther
and Reeh 2011). Figure 1 on the right gives an overview of the
opencast mine Garzweiler situated within the Rhenish lignite
mining area as well as the autobahn A 44 and A 61.
The first soils under the planned route of the A 44 were
dumped close to the proposed autobahn interchange Jackerath in
the south in 1999. From this time on the dump has continuously
progressed to restore the original topography. The dumping
taking place in area close to the A 44 should be completed by
the year 2016. An aerial photograph in figure 1 shows the
Garzweiler open cast mine in the background as well as the
extent of the area that has been reused for agricultural purposes
in the foreground. The A 44 route can easily be seen between
the farmland.
2025
2017
2006
AK Holz
A 44
A 44
A 46
A 61
A 61
A 44 demolished
A 44 planned
A 46
AK
Jackerath
Figure 1. Mining area of Garzweiler (left) and an aerial photograph of
the planned A 44 route (right)
