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Assessment of bio-mechanical reinforcement materials influencing slope stability,
based on numerical analyses
Évaluation des matériaux de renforcement bio-mécaniques qui influencent la stabilité des pentes
par des analyses numériques
Koda E., Osinski P.
Department of Geotechnical Engineering, Warsaw University of Life Sciences - SGGW, Warsaw, Poland
ABSTRACT: The article is an answer proposal for the conclusion stated in European regulations regarding the environment friendly
and more sustainable development, which among others includes utilising secondary and recycled material in order to obtain durable
and stable cuttings and embankments. Bearing in mind that the slope stability and erosion control on embankments are the issues
rising the nowadays geotechnics awareness through all around the world, the paper content provides the alternative engineering
solutions to such problems. The techniques proposed in the paper mainly consist of the proper vegetation cover implementation on
embankment slopes, the reinforcement of earth structures by utilising geotextiles and a combination of those two. Additionally, it is
presented how secondary materials could be used as a vegetation development accelerating and enhancing material. In order to prove
the reliability and efficiency of such activities the laboratory material tests and numerical modeling of slope failures were conducted.
RÉSUMÉ : L'article est une proposition de réponse à la conclusion énoncée dans les règlements européens concernant
l'environnement de développement favorable et plus durable, ce qui comprend entre autres l'utilisation des matériaux de récupération
et de recyclage afin d'obtenir des déblais et remblais stables et durables. Il est admis que la stabilité des pentes et le contrôle de
l’érosion sur les remblais sont des problèmes qui apparaisse comme des priorités pour la géotechnique actuelle. Le papier propose des
solutions d’ingénierie à ces problèmes. Les techniques proposées dans le document se composent principalement de la mise en œuvre
de couverture végétale sur les talus, le renforcement des structures en terre en utilisant par géotextiles et une combinaison des deux.
En outre, il est présenté comment les matériaux secondaires pourraient être utilisés comme un développement de la végétation
accélérant et en améliorant le matériau. Afin de prouver la fiabilité et l'efficacité de telles activités, les essais de matériaux en
laboratoire et la modélisation numérique des ruptures de pente ont été effectuées
KEYWORDS: slope stability, reinforcement, vegetation cover, recycled materials, landfill.
1 INTRODUCTION.
The most significant element of the embankment type landfill
reclamation process is the reinforcement and biological
stabilisation of slopes, which are very sensitive to several
destabilisation processes like i.e surface erosion. The landfill
stability improvement activities are divided into phase 1 -
technical reclamation (implementation of civil engineering
techniques), and phase 2 - biological restoration (establishment
of the vegetation cover). For both of them it is highly
recommended to use such recyclable materials as sewage sludge
and fly ash as a landfill reinforcement filling (CEN/BT, 2009).
In 2012, in Poland the production of fly-ashes from the coal
combustion was 18.5 mln tones. The amount of slag and ashes
disposed on Polish landfills and usable for the road
embankment construction and land reclamation is 261.8 mln
tons. Furthermore, the annual production of sewage sludge in
Poland is also significant - 500 000 tones, and could be
successfully utilised in landfill reclamation process, as a rich in
nutrients fertilizer (Koda et al 2012). The combination of
carefully selected types of fly-ash, sewage sludge, soil and
vegetation cover can be excellent alternative for the heavy
engineering activities for the landfill slopes reinforcement. All
the presented solutions are based on the analyses conducted at
the Radiowo landfill site located near Warsaw.
2 SITE DESCRIPTION
The Radiowo landfill (embankment type) was established in
1962. It covers approximately 15 ha and the altitude is 60 m
high. No protection system against the environmental pollution
was introduced into the surrounding area at the start of the
landfill operation.
The municipal solid waste was disposed there up to the early
90’s. The local landslides treatment, changes in further
exploitation, and the reinforcement treatment were required.
Since 1993 only non-composted waste from the compostory
plant has been disposed there (approximately 300 tons/day).
The remediation works on the landfill have been carried out
since 1994. They include: slopes forming and planting, stability
improvement solution, mineral capping, bentonite cut-off wall
as a limitation of the groundwater pollution and a peripheral
drainage.
The in situ and laboratory tests for Radiowo landfill has been
performed since 1993. The field investigation consists of
settlement measurements, geotechnical tests of waste, back
analysis (as well as slope failure tests), quality tests of sealing
(capping layer and vertical barrier) and filter materials. In the
Radiowo landfill case, the morphological composition of waste
creates an additional factor influencing the mechanical
parameters. The organic matter content for non-composted
waste is ca. 5 %. A location map involving cross sections
selected for slope stability analyses is presented in Figure 1.
Nowadays, the landfill site is planning to be adopted as a
winter sports activity complex. The construction plan has
already been accomplished and accepted by a legal body, which
is a requirement when considering new development plan for
contaminated sites (for more detail please refer to Koda 2012).
3 UTILISATION OF ANTHROPOGENIC MATERIALS
One of the elements of the landfill reclamation process is the
construction of capping system. It is a landfill surface cover
protecting against the rainfall infiltration (limitation of leachate
penetration). It provides good establishment conditions for the
vegetation cover, and significantly enhances slopes stability.
